Relationships between activity patterns and foraging strategies of Yellowstone grizzly bears
by Albert L Harting
A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in
Biological Sciences
Montana State University
© Copyright by Albert L Harting (1985)
Abstract:
Eleven grizzly bears (Ursus arctos horribilis) were radiotracked in Yellowstone National Park and
vicinity in 1981 and 1982. Principal objectives of the study were 1: to examine the daily and seasonal
activity patterns of Yellowstone grizzlies and to determine what influence certain temporal and
environmental factors had on these activity patterns and 2: to examine the interrelationships of food
habits, habitat use, movements, and activity patterns. Two methods for rating the quality of a bear’s
occupied habitat were employed. One method considered the abundance, diversity, and relative value
to grizzlies of the vegetation occurring at field-checked relocation sites. The second method utilized
existing habitat maps and a spatial information computer package to identify the habitats surrounding
relocation points. These habitat types were then rated according to a system of Habitat Importance
Values developed by the Interagency Grizzly Bear Study. Theoretical aspects of grizzly bear foraging
strategies and predatory habits were also considered.
Environmental factors which had a significant effect on grizzly bear activity patterns were temperature,
precipitation, and cloud cover. Some of the influence of environmental variables on bear activity could
be explained according to their probable effect on olfactory perception. Temporal factors found to be
important were season and time of day (diel period). Grizzlies in this study were primarily crepuscular
and . nocturnal but individual bears differed significantly in their activity patterns. Individual
differences in grizzly bear food habits and habitat use were reflected in their characteristic activity
patterns and movements. Bears which occupied vegetatively poor habitat appeared to be more reliant
on "supplemental" food sources (meat or garbage) than bears in rich mesic areas. The use of trained
bear dogs to retrace grizzly bear movements proved to be a valuable adjunct to traditional research
tactics. RELATIONSHIPS BETWEEN ACTIVITY PATTERNS
AND FORAGING STRATEGIES OF
YELLOWSTONE GRIZZLY BEARS
by
Albert L. Harting, Jr.
A thesis submitted in partial fulfillment
of the requirements for the degree
of
Master of Science
in
Biological Sciences
MONTANA STATE UNIVERSITY'
Bozeman, Montana
March 1985
APPROVAL
of a thesis submitted by
Albert L. Harting
This thesis has been read by each member of the thesis committee
and has been found to be satisfactory regarding content, English
usage, format, citations, bibliographic style, and consistency, and is
ready for submission to the College of Graduate Studies.
7 . / ? Sr 6
chairperson. Graduate Committee
Date
Approved for the Major Department
2S hbn;ary , IcISS
Date
Z
Ak
%
Head, Major Department
Approved for the College of Graduate Studies
Date
Graduate Dean
ill
STATEMENT OF PERMISSION TO USE
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presenting
this
thesis
in
partial
fulfillment
requirments of a master's degree at Montana State University,
that
the
of
I agree
the Library shall make it available to borrowers under rules
Library.
the
of
Brief quotations from this thesis are allowable without
special permission,
provided that accurate acknowledgement of
source
is made.
Permission
for extensive quotation from or reproduction of
this
thesis may be granted by my major professor, or in his absence, by the
Director of Libraries when, in the opinion of either, the proposed use
of the material in this thesis is for scholarly purposes.
or
use of the material in this thesis for financial gain shall not be
allowed without my written permission.
Signal
Date
Any copying
V
ACKNOWLEDGEMENT
I
am
sincerely
grateful
to the
following
people
for
their
contributions to this study. My major professor. Dr. H. D. Picton, was
the
source
of
many
valuable insights which were
success of this project.
Study,
first
opportunity
proposed
and
possible.
Dr.
Drs.
of
the
R. Knight, Interagency Grizzly Bear
project
and
R. L. Eng and R. E. Moore reviewed the manuscript and
made many constructive suggestions.
Services,
to
provided the
research
I
without which the study would not have been
funds
the
R.
critical
Ms. Georgia Ziemba, MSU Computing
was extremely helpful with the statistical analysis aspects
the study.
I am especially grateful to Dave
Mattson,
IGBS,
for
providing me with his preliminary data pertaining to grizzly bear food
habits
and
habitat use.
The fieldworkers who assisted me with
collection,
especially
thanks
for
remaining enthusiastic despite the long
sleep,
and oftentimes dreary conditions.
deserve
Finally,
credit
I
cooperation
Harting,
providing
S.
Rhodes,
to
My wife,
give me ongoing
Linda,
many
lack
of
R. Vaughan and L. Lobos
inspiration as only
throughout this project.
deserve
hours,
they
wish to thank my family for their enduring
managed
assistance.
for
Terry Jones and Kevin
data
knew
patience
My parents and my uncle,
encouragement
and
how.
and
Frank
financial
and son, Aaron, contended with the many
long absences and mysterious moods which every graduate student surely
knows.
I
vi
TABLE OF CONTENTS
Page
LIST OF TABLES................................. '..............
viii
LIST OF FIGURES...............................................
x
ABSTRACT......................................................
xii
INTRODUCTION..................................................
I
STUDY AREA....................................................
3
Administrative Context..................
Geological Background.......................................
Vegetation Zones............................................
Study Area Sub-Units..... ...................................
Gneiss Creek/Hebgen Lake Sub-area........................
Nez Perce Cr./Firehole River Sub-area.,..................
Blackball Plateau/Washburn Range Sub-area.......
Climatology.................................................
3
3
5
7
8
9
9
10
METHODS.................................
12
Data Collection..........................................
Trapping and Radio-Tracking........................
Activity Monitoring......................................
Habitat Use and Scat Data Collection.....................
Dog Tracking....................................
Data Analysis...............................................
Activity Data............................................
Community Site Data Analysis.............................
Computer Relocation Habitat Scans.............
Scat Data Analysis.......................................
Minimum Daily Movements and Home Range Estimates.........
12
12
13
14
15
16
16
17
20
23
24
RESULTS.......................................................
25
Activity Data...............................................
Temperature..............................................
Precipitation and Ground Moisture..........
Wind Speed................................... J..........
Cloud Coyer..............................................
Seasonal and Monthly Effects.............................
25
25
28
28
30
30
vii
TABLE OF CONTENTS— Continued
Page.
Time of Day Effects......................................
Seasonal Activity Patterns by Diel Period............
Individual Bear Patterns.............................
Community Site Analysis........
Relocation Habitat Scans..........................
Scat Analysis...............................
Movements and Home Range Use....... ..................
Tracking Grizzlies with Bear Dogs.......................
32
35
38
42
44
46
48
49
DISCUSSION.................. .'.................................
52
Activity Patterns...........................................
Diel Patterns....................................
Seasonal Activity Levels.................................
Environmental (Weather) Effects...............
Energetic Agendas of the Primary Study Bears................
Bear 59..................................................
Bear 38..................................................
Bear 50..........
Bear 15...........
Bear 76..................................................
Grizzly Bear Foraging Strategies............................
Theoretical Considerations of Grizzly Predation
on Ungulates.... ...................
Tracking Grizzlies with Trained Bear Dogs...................
52
52
53
55
62
63
66
67
69
72
75
80
82
CONCLUSIONS................................
85
LITERATURE CITED.........................
88
APPENDICES.............................
95
Appendix A - Community Site Field Form......................
Appendix B - Tables of Habitat Parameter Values and
Community Site Data........
96
99
viii
LIST OF TABLES
Page
Table I. Scientific
names
and abbreviations
for
habitat
types referred to in the text......................
Table 2. Distribution of activity records by bear,
year................................
season,
7
and
13
Table 3. Age, sex, and monitoring period for the five primary
study bears............................................
13
Table 4. Mean values for Food Value (FV), Understory Cover
(C ), Understory Species Diversity (H ), and Community
Si£e Quality Index (CSQ) for Bears 15,U 38, 50, 59, and
76.... ..................................................
43
Table 5. Grizzly bear Area Food Scores (FS )^ mean amount of
Edge per relocation scan circle (E), mean Habitat
Diversity in scan circles ( H ) , and Relocation Habitat
Richness scores (RHR).................................
44
Table 6. Mean Scat Values (SV) scores for the primary study
bears..............................................
46
Table 7. Scat
summary
for primary study
bears:
percent
"digestible"
diet
volume and
percent
frequency
occurrence for important diet item groups...............
47
Table 8. Consecutive minimum daily movements
(km) for
the
five primary study bears................................
49
Table 9. Short
49
term
home ranges for the primary
study
bears...
Table 10. Energetic
efficiencies
(EE),
characteristic
contagiousness (A ), and monthly preference values
for the most important diet items of Yellowstone
grizzlies as used in the community
site and scat
quality analyses.......................................
100
Table 11. Monthly Food Values (FV) of the most important
items
of Yellowstone grizzlies as used in
community site analyses.......
101
diet
the
ix
LIST OF TABLES— Continued
Page
Table 12. Unit area importance values (IVU's) used to score
habitat types for habitat richness analysis............
102
Table 13. Community site scores for Food Value (FV), Understory
Cover (C ), Understory Species Diversity (H ), and
CommunityuSite Quality (CSQ)................. V ........
103
X
LIST OF FIGURES
Page
Figure I. Map of the study area.......... ........................
Figure 2.
4
Relationship
between
temperature
(in
C)
and
probability of bear activity............................
26
Relationship
between
temperature
(in
probability of bear activity in spring.
and
.....
26
Figure 4. Relationship
between
temperature
(in
C)
and
probability of bear activity in summer..... .........
27
Figure 3.
Figure 5.
C)
Relationship
between
temperature
(in
C)
and
probability of bear activity in fall...................
27
Figure 6. Relationship
between
precipitation
type
and
probability of bear activity....... ...................
29
Figure 7. Relationship between ground moisture and
of bear activity..................
29
probability
Figure 8. Relationship
between wind speed (in km/hr)
and
probability of bear activity.........................
31
Figure 9. Relationship between cloud cover and probability of
bear activity.........................................
31
Figure 10. Relationship between month and and the probability of
bear activity...............
33
Figure 11. Relationship between diel period and probability of
bear activity annually and seasonally.................
33
Figure 12. Probability of bear activity according to hour of the
day annually.........
34
Figure 13. Probability of bear activity according to hour of the
day in spring..........................
36
Figure 14. Probability of bear activity according to hour of the
day in summer.............................
37
xi
LIST OF FIGURES— Continued
Page
Figure 15. Probability of bear activity according to hour of the
day in fall. .........................................
39
Figure 16. Overall probability of activity for the five primary
study bears...........................................
40
Figure 17. Probability of activity according to diel period for
all monitored bears (including all activity records
from all bears from both monitoring years) and for
primary study bears #76 and #59......................
40
Figure 18. Probability of activity according to diel period for
primary study bears #50, #38, and #15.................
41
Figure 19. Probability of activity according to diel period for
Bear 50 annually and by season...................... .
42
xli
ABSTRACT
Eleven grizzly bears (Ursus arctos horribilis) were radiotracked
in Yellowstone National Park and vicinity in 1981 and 1982. Principal
objectives of the study were I: to examine the daily and seasonal
activity patterns of Yellowstone grizzlies and to determine what
influence certain temporal and environmental factors had on these
activity patterns and 2: to examine the interrelationships of food
habits, habitat use, movements, and activity patterns. Two methods
for rating the quality of a bear’s occupied habitat were employed. One
method considered the abundance, diversity, and relative value to
grizzlies of the vegetation occurring at field-checked relocation
sites. The second method utilized existing habitat maps and a spatial
information computer package to identify the habitats surrounding
relocation points. These habitat types were then rated according to a
system of Habitat Importance Values developed by the Interagency
Grizzly Bear Study. Theoretical aspects of grizzly bear foraging
strategies and predatory habits were also considered.
Environmental factors which had a significant effect on grizzly
bear activity patterns were temperature, precipitation, and cloud
cover. Some of the influence of environmental variables on bear
activity could be explained according to their probable effect on
olfactory perception, Temporal factors found to be important were
season and time of day (diel period). Grizzlies in this study were
primarily crepuscular and .nocturnal but individual bears differed
significantly in their activity patterns. Individual differences in
grizzly bear food habits and habitat use were reflected in their
characteristic activity patterns and movements. Bears which occupied
vegetatively
poor
habitat
appeared to be
more
reliant
on
"supplemental" food sources (meat or garbage) than bears in rich mesic
areas. The use of trained bear dogs to retrace grizzly bear movements
proved to be a valuable adjunct to traditional research tactics.
I
INTRODUCTION
Prior
studies
of the grizzly bear (Ursus arctos horribilis)
in
the Yellowstone ecosystem have contributed a wealth of data pertaining
to
the
food
habits,
habitat
use,
and
general
ecology
of
this
*
population
1981;
(Mealey 1975;
Graham 1978;
Craighead and Mitchell 1982;
Kendall 1981;
Knight et al.
Knight et
1984).
al.
These data
provided the framework within which present management strategies were
developed.
less
But
certain,
as the welfare of the Yellowstone grizzlies
appears
management decisions become increasingly complex and a
need for data of still finer resolution becomes apparent.
Recently,
expanding
Schleyer
(1983)
grizzlies
with
Sizemore
Two
prior
forage
(lake,
examined
respect
to
the
studies
temporal
patterns
and
of
Yellowstone
environmental
variables.
dealt
partially
with
grizzly
bear
in
three physiographically distinct
and
valley/plateau),
occupied a protein food niche.
requirements
of
an
feeding
and felt that
bears.
foraging
Mealey (1975) found that Yellowstone grizzlies
mountain,
maintained
activity
behavior.
(1980) also studied the activity patterns of grizzly
strategies.
to
emphasis has been placed on bear
appeared
"economies"
bears
mainly
Sizemore (1980) computed the energetic
individual grizzlies and described how
energy balance by utilizing reserve fat to
these
bears
supplement
the available foraging opportunity.
i
2
None of the studies cited above have attempted to correlate
from
bear
food
patterns
for
overview
of
habits and habitat use with data
individual
the
bears.
on
This study sought
grizzly bear's activity
bear
to
data
activity
provide
pattern/foraging
an
strategy
complex.
The specific objectives of this study were:
1.
To examine the daily and seasonal activity patterns of Yellowstone
grizzlies,
and
to
determine how these patterns
fluctuated
between
individual bears and under different environmental conditions.
2.
To determine how a given bear's activity patterns, movements, food
habits,
patterns
and habitat use were interrelated, and to contrast individual
to see how variation along one parameter appeared to
affect
the others.
3.
To
develop
a
conceptual
overview
of
grizzly
bear
foraging
strategies with reference to established optimal foraging theories.
4.
To
research.
explore
the feasibility of using trained bear dogs
in
bear
3
STUDY AREA
Administrative Context
The
study area was located in the Greater Yellowstone
Ecosystem
of Wyoming and Montana and included parts of Yellowstone National Park
and
contiguous
National Forest land (Figure I).
All of
Yellowstone
Park and much of the remainder of the study area have been
as
"Management
designated
Situation I" grizzly habitat in accordance
with
the
grizzlies' threatened status under the Endangered Species Act (87 stat
884,
16U.S.C.
habitat
1531-1543).
maintenance
This designation specifies that "grizzly
and improvement...
and
grizzly-human
minimization will receive the highest management priority.
decisions
habitat
will
favor
the
needs of the grizzly
bear
Management
when
and other land use values compete." (USFS and NPS
Service Grizzly Bear Policy stipulates that management
will
be designed to "I.
populations
and,
2.
minimize
grizzly
1979)
Park
perpetuate wild,
conflict
The
policies
free-ranging grizzly
conflicts between humans and
bear
grizzly
bears by reducing man-generated food sources and by regulating visitor
distribution."
Geological Background
The
present
episodes
ultimately,
of
landscape of Yellowstone was produced
sedimentation,
faulting,
volcanic
by
repeated
activity
and,
glaciation (Keefer 1972). Two major types of bedrock were
G A L L A T IN N A T L . FO R.
Y E LLO W S T O N E PARK BO U N DAR Y
I
MT. WASHBURN
WEST YELLOWSTONE'
OLD FAfTVFUL
B R ID G E R -T E T O N N A T L . F O R .
SUB-AREAS
KILOMETERS
Figure I. Map of the study area
5
formed
during periods of exceptional volcanic action in the
Cenozoic
era. The Absaroka bedrock was formed from major eruptions in the early
Eocene
which buried Yellowstone beneath thousands of feet of ash
and
lava. The Absaroka rocks were primarily andesite and basalt. The other
major
bedrock type- the Yellowstone volcahics- was
three
cycles
period.
ago
a
accompanying
caldera
pyroclastic activity
in
the
Quaternary
in
major
eruption
formation
of
of rhyolitic pumice
the
2600
square
the central portion of the Park.
and
ash
kilometer
ago.
Plateau
These
Rhyolite,
Eaton et al.
flows were
but
principally
the
some basalt flows have also been
may be the seminal stage of a fourth
flow
75,000
so-called
identified.
(1975) suggested that the present hydrothermal
Yellowstone
the
Yellowstone
Lava continued to
rhyolite,
years
and
ring fracture zones encircling the caldera until roughly
years
in
intense
during
The most recent of these cycles climaxed about 600,000
with
from
of
deposited
activity
volcanic
cycle
rather than the final phase of the third.
Yellowstone was glaciated at least three times.
of these,
The most
the Pinedale glaciation, occurred 25,000 to 8,500 years ago
and covered up to 90% of the present Yellowstone Park.
the
recent
receding Pinedale glaciers eventually burst causing
Dams formed by
catastrophic
flooding, the results of which are still evident in many areas.
■'
Vegetation Zones
Although
glaciation
and erosion have redistributed and
altered
the composition of the original Absaroka and Yellowstone deposits, the
6
present
vegetation appears to depend in large part on the
bedrock
type.
underlying
Despain (1973) described three major vegetation
within Yellowstone National Park.
zones
The lodgepole pine (Pinus contorta)
zone appears to be strongly associated with poor soils of
Quaternary
rhyolite
pine
origins.
occasional
sites.
(m)
It
spruce
This
and
is
(Picea)
dominated by climax
and fir (Abies)
lodgepole
occurring
in
favorable
zone typically occurs at elevations of 2320-2560
receives
relatively low
(51-102
with
meters
centimeters,
cm)
annual
is positively associated with
the
richer
precipitation.
The
spruce-fir
zone
Absaroka (andesitic) volcanic soils. Mature stands may be dominated by
either
spruce
albicaulis).
or fir or,
near
Successionally
in the understory and,
timberline,
whitebark
pine
(Pinus
young stages include both spruce and fir
frequently, vigorous stands of lodgepole pine.
This zone occurs above 2560 m and generally receives greater than
102
cm annual precipitation.
The
third major vegetation zone is the Douglas-fir
menziesii)
zone.
(Pseudotsuga
This, zone is characterized by Douglas-fir
as
the
dominant forest overstory with some spruce,
fir, lodgepole, and aspen
(Populus
Big sagebrush
tremuloides)
tridentata)
overlies
sediments
and
mixed
and
in favorable sites.
mixed grasses are common in open
areas.
depths of glacial till and a bedrock
granite
at
elevations
of
precipitation is generally less than 51 cm.
of
1830-2320
(Artemesia
This
zone
Quaternary
m.
Annual
7
Study Area Sub-Units
Grizzly
bears
were
radiotracked
throughout
much
of
the
western and northcentral portions of Yellowstone Park at various times
during this study.
principal
the
However, many of the data were collected in three
subareas (Figure I).
Habitat types described below follow
classification of Mueggler and Stewart (1980) for
grassland
and
shrubland and Steele et al. (1979) for forested areas as identified by
Despain (1984) in Yellowstone Park (Table I).
Table I. Scientific names and abbreviations for habitat types referred
to in the text. Habitat types follow the systems of Mueggler
and Stewart (1980) for grassland and shrubland and Steele
et al. (1979) for forest types.
Forest habitat types:
ABLA/VAS C-VAS C
ABLA/VASC-CARU
ABLA/VASC-PIAL
ABLA/CACA
PIEN/EQAR
ABLA/THOC
ABLA/CAGE
ABLA/LIBO-VASC
ABLA/VAGL-VAGL
ABLA/CARU
PICO/CARO
PICO/PUTR
PSME/SYAL
PSME/CARU
PIAL/VASG
Abies lasiocarpa / Vaccinium scoparium-V.scoparium
A. lasiocarpa / V^_ scoparium-Calamagrostis rubescens
A. lasiocarpa / Vj_ scoparium-Pinus albicaulis
A. lasiocarpa / Calamagrostis canadensis
Picea engelmannii / Equisetum arvense
A. lasiocarpa / Thalictrum occidentale
A. lasiocarpa / Carex geyeri
A. lasiocarpa / Linnea borealis-V.scoparium
A. lasiocarpa / Vj_ globulare-V.globulare
A. lasiocarpa / C^ rubescens
Pinus contorts / Carex rossii
P. contorts / Purshia tridentata
Pseodotsuga menziesii / Symphoricarpos albus
P. menziesii / Cj_ rubescens
P . albicaulis / V . scoparium
Non-forest habitat types:
FEID/AGSP
FEID/AGCA
FEID/AGCA-GEVI
FEID/DBCE
DECE/Carex spp.
ARTR/FEID
ARTR/FEID-GEVI
Festuca idahoensis / Agropyron spicatum
F . idahoensis / A 1. caninum
F . idahoensis / A^ caninum-Geranium viscosissimum
F . idahoensis / Deschampsia caespitosa
D . caespitosa / Carex spp.
Artemisia tridentata / F^ idahoensis
A. tridentata / F . idahoensis-G. viscosissimum
8
Gneiss Creek/Hebgen Lake Sub-Area
This area lies along the western boundary of Yellowstone Park and
adjacent parts of the Gallatin National Forest.
west
by
Hebgen
Gallatin
Range.
notably
area
Lake
and on the east by the
It is dissected by several
Gneiss Creek,
Cougar Creek,
It is bounded on the
southern
major
end
of
the
drainages, most
and Teepee Creek.
Most of the
is dominated by climax lodgepole pine with bitterbrush
(Purshia
tridentata) understory (PICO/PUTR habitat type) at elevations of 19802440
m.
occur
Large marshy areas with thick stands of willow (Salix
along
the lower reaches of Gneiss
around Hebgen Lake.
are
more
complex
occurring with the lodgepole.
(VASC and CARU phases),
of
aspen
Cougar
with
spruce
and
and
fir
commonly
Common habitat types include ABLA/VASC
ABLA/THOC and other ABLA habitats.
are found throughout the
area.
meadows are located along many of the creek bottoms.
areas
Creek,
The northern and eastern portions of this subarea
topographically
stands
Creek,
spp.)
Mesic
Scattered
grass/forb
Sub-xeric
open
with sparse to moderately-dense stands of big sagebrush in
the
ARTR/FEID habitat type (GEVI phase) are found along certain ridges and
southern exposures.
Bear-human
conflicts
are
a
major
concern
in
this
area.
Residential and summer homes are scattered along Duck Creek and around
Hebgen
Lake.
fishing.
the area.
Both
Cougar
Creek
and Duck Creek
are
popular
Several campgrounds and summer resorts are also located
for
in
9
Nez Perce Cr./Firehole River Sub-area
This
central
within
subarea
part
the
Central
is
located
north of Old Faithful
of Yellowstone Park.
and ABLA/CAGE.
the
The majority of this
vast lodgepole-pine zone in the western
Plateau.
in
west-
area
reaches
lies
of
the
The most abundant habitat types are ABLA/VASC-VASC
Serai stages of both types are dominated by lodgepole
pine.
Engelmann Spruce (Picea engelmanii) and subalpine fir are also
common
in
pockets.
the
overstory.
Nez Perce Creek,
the major waterways.
Whitebark pine is
present
in
isolated
Sentinel Creek and the Firehole River are
Wet forests consisting of several habitat types
occur along these streams.
The ABLA/CARU habitat type is common.
Lower
Geyser Basin lies in the center of this
range
from about 2320 m over most of the area to a maximum of 2600
on
Mary
thermal
Creek
Mountain.
sub-area.
The
Human activity is restricted
Elevations
primarily
to
areas around the geyser basin and to fishing along Nez
and the Firehole.
m
the
Perce
The Grand Loop road also passes through the
center of this sub-area.
Blackball Plateau/Washburn Range Sub-area
This is the largest of the three sub-areas.
high
peaks
It encompasses
and alpine tundra of the Washburn Range and the
rolling,
grassy slopes along Antelope Creek and in the Blackball Plateau.
of
this
sub-area
Yellowstone River,
types
the
lies within the spruce-fir
the Douglas-fIr zone.
ABLA/CARU
and PSME/SYAL
and,
along
The most abundant
are ABLA/VASC-VASC and ABLA/VASC-PIAL.
ABLA/THOC,
zone
the
Much
the
habitat
Other common types are
habitats.
Whitebark
pine
I
10
occurs at mid to high elevations in a number of locations.
xeric
Large sub-
meadows of grasses and various forbs with scattered pockets
timber are present in the Blacktail Plateau and Antelope Creek
Common grassland habitats are the ARTR/FEID,
GEVI types.
of
areas.
FEID/AGSP and FEID/AGCA-
The elevation ranges from 2075 m in the Blackball Plateau
to 3125 m on Mount Washburn.
Climatology
Temperature
and
precipitation data were abstracted from
summaries
for
the "Yellowstone
reporting
stations at Mammoth,
Drainage,
Wyoming"
Tower Falls,
division
Old Faithful,
(with
and Lake in Yellowstone
Park and at Crandall Creek and Clark east of the park,
Snow survey data were collected at Canyon,
annual
Norris,
NOAA 1980-82).
West Yellowstone,
and Lupine Creek (SCS 1983). Snowfall for December 1980
through April 1981 (winter preceding the first field season) was
below the long term mean.
above
normal.
winter/early
The
Temperatures for the same period were well
snowpack
spring
1981
(in water equivalent inches)
was well below
normal
at
all
for
light
growing
late
reporting
stations . (means of 54% and 55% of the long-term average in March
April,
4.1%
and
respectively). Heavy rains in May and June compensated for the
snow
pack
season
so that cumulative precipitation
(May
through
July)
was
28.9%
for
the
above
primary
normal.
Temperatures for this period also averaged slightly above normal.
The
remainder of the first field season (August and September) was hot and
dry, with temperatures averaging 6.9% above the norm and precipitation
50% below normal.
11
Precipitation
(winter
the December 1981 through April
snowpack
averaged
8.1% below the
long
term
in March and April was 102% and 117%,
long-term average.
means.
of the
Precipitation for the May to July 1982 period
slightly (3.3%) below normal so that overall available
the
period
Cumulative
respectively,
for the primary growing season was at or above normal.
of
1982
preceding the second field season) was 37.5% above normal and
temperatures
only
for
moisture
The remainder
second field season (August and September) was unusually
(precipitation
32.9% above normal) with temperatures
was
averaging
wet
5.0%
above normal.
Despite
the
the apparent contrasts between the weather patterns
1981 and 1982 field seasons,
timing of phenological
appeared to be fairly similar for both years.
late
for
development
Peak succulence was in
May to June and most plants were in flower or fruit by early
to
mid July. The similar phenology during the two years may relate to the
fact that many of the important bear forage species were high altitude
perennials
which
characteristically have a climate-species
function of about two years (Picton pers. comm.).
transfer
METHODS
Data Collection
Trapping and Radio-Tracking
Grizzly
bears were trapped by the Interagency Grizzly Bear Study
Team (IGBS) or by National Park Service (NPS) personnel using
traps
or
Aldrich
foot
snares.
Eleven
different
radiotracked during various phases of the study.
bears
were
culvert
grizzlies
were
Data from all eleven
used in the activity pattern analyses.
Five bears
were
selected (according to the acquired data base and the availability
of
prior data for each bear) for a more detailed analysis of the activity
pattern/habitat use interaction (Tables 2 and 3).
The
routine
location
aerial
of
instrumented bears was first
surveys by IGBS personnel.
A
determined
temporary
from
monitoring
station was subsequently established at a suitable vantage point
the "target" bear.
hand-held,
elevated
second
tracking
Several different tracking systems were used.
two-element
radio-tracking.
and
near
Yagi
antenna was generally used
for
A
ground
A truck-mounted 4-element Yagi antenna which could be
rotated
5 m above the cargo bed was
(1982) field season.
used
during
This system proved useful while
night­
from roads or when slight elevation changes provided a
improved signal.
the
much
13
Table 2. Distribution
of activity records by bear, season, and year.
Each
activity record represents one monitoring
period,
ranging from 10 minutes to 2 hours, during which the bear's
activity status was determined.
Bear No.
Spr
15
38
50
59
76
others
total
0
75
40
0
0
0
115
1981
Summ
Fall
56
97
78
0
0
49
280
24
0
50
0
0
54
128
*
Spr
0
0
0
0
0
0
0
1982
Summ
0
0
0
44
124
151
319
Fall
0
0
0
0
0
0
0
Both Years
Spr Summ Fall
0
75
40
0
0
0
115
56
97
78
44
124
200
599
24
0
50
0
0
54
128
A
Spring=March-May; Summer=June-August; Fall=September-October
Table 3. Age, sex, and monitoring period for the five primary study
bears . Ages given represent age when bear was monitored for
this study.
Bear #
Age
15
38
50
59
76
Sex
11
10
AdJ
4
2
Monitored Yr. and Season(s)
1982 :summ, fall'*'
1981:spr,summ
1981:spr,summ,fall
1982:summ
1982:summ
F2
F
F
F
I Bear 15 was also tracked with trained bear dogs in 1981.
2 None of the females radiotracked during the study were
by cubs.
accompanied
3 Ad=Adult of undetermined age (5 yrs or older)
Activity Monitoring
All of the study bears except #15 were equipped with tilt collars
(Telonics,
Inc.)
designed
movements of the head.
to indicate activity status according
to
Frequent fluctuations from one pulse mode
to
the other suggested that a bear was active.
with
a
standard
(non-tilt)
collar.
Bear #15 was instrumented
His
activity
status
was
14
ascertained
via
the
"integrity" of the
erratic signal strength,
regarded
as
probable
investigators
indicator
have
signal.
Such
factors
obvious directionality changes,
indicators
of
activity.
found that this method was
However,
often
of activity (Lindzey and Meslow 1976;
etc.,
an
as
were
other
unreliable
Garshelis and Pelton
1980). Activity was occasionally determined from direct observation.
At
regular
intervals,
generally
hourly
during
the
day
and
bihourIy at night, the bear's signal was monitored for a minimum of 10
to
15 minutes.
During each monitoring session,
the bear's
level was recorded using one of five activity designations:
mostly
inactive
divided
between
intermittent
with
active
brief
intermittent
and inactive
quiet spells,
activity
periods,
activity
inactive,
spurts,
mostly
evenly
active
and entirely active (erratic mode
with
shifts
almost constantly). These were later reduced to two categories, active
or inactive,
to facilitate analysis.
data on precipitation,
direction
analyzed
and
to
During each monitoring
period,
cloud cover, ground cover, wind velocity, wind
temperature
were collected.
determine their influence,
These data
if
any,
on
were
bear
later
activity
patterns.
Habitat Use and Scat Data Collection
The
range
precise location of the study bears was determined by
triangulation
situations
approximate
integrity,
whenever
possible.
During
the
generally precluded triangulation fixes,
position was deduced from single
intervening topography, etc.
bearing
night,
close
field
thus the
bear's
fixes,
signal
Locations derived from these
15
latter
indices
were
considerably less reliable
than
triangulation
fixes and the resultant data were treated accordingly.
Once the bear had vacated an area,
site
and
investigators returned to the
searched for feeding activity,
additional
evidence of bear activity.
scats,
day beds,
A "community
and
site
any
analysis"
(Appendix I) was conducted according to the procedures outlined by the
IGBS
(Knight
encountered.
et al.
When
1984) at all locations where bear activity
no
bear sign was found,
believed to be accurate,
These
analyses
included
but
radio
fixes
were
community site analyses were also completed.
a determination of habitat
type
following
Mueggler and Stewart (1980) for grasslands and shrublands and
et al.
was
(1977) for forested areas.
Pfister
Species lists were prepared at all
community sites. Cover values were estimated ocularly for each species
recorded. Specimens which could not be identified at least to genus in
the
field
specimens
were
were
collected for
verified
later
identification.
at the Yellowstone
Questionable
herbarium
at
Plant nomenclature followed Hitchcock and Cronquist (1973).
topographic
and
physiognomic features were also
noted
Mammoth.
Relevant
during
each
community site analysis.
Scats
of the year were routinely collected whenever encountered.
Scats were analyzed for content by Montana Fish,
Wildlife,
and Parks
personnel as described by Knight et al. (1980).
Dog Tracking
Trained
obtain
bear
dogs were used during July 1981 in
more precise data on bear microhabitat use.
Two
an
effort
to
professional
16
bear
hunters/guides
this
phase of the study.
and
from Oregon volunteered their time to help
They brought eight of their hounds
related breeds) to Yellowstone in July 1981.
strategies were used.
be
frequented
site.
Such
by
a
Two basic
an
tracking
bears and then to track a grizzly away
site
was
available where
a
rendering
from
bear
lure for our purposes.
In
this
plant
identity
and
current
location were generally
approach
was
to determine the day bed location of
bear
triangulation,
and
then return the
case,
truck
1983).
unknown.
a
the
The
was
possibility
were
The
other
radio-collared
following
fixes
morning
alleviated
of unpleasant encounters with the study bear.
equipped with loud bells and were restrained on
times.
The
leashes at
to
This
the
dogs
all
Despite these precautions, NPS officials concluded that due to
inherent
was
preferable since periodic radio
as
bear's
retrace the bear's overnight movements starting at the bed site.
strategy
to
this
left considerable animal fat in the topsoil which served
ersatz
by
(Plotts
One was to take the hounds to a site known
overturned along Highway 191 two years previous (Schleyer
accident
with
risks and possible visitor annoyance,
the use of bear
an unacceptable approach to bear research within the confines
the Park.
Consequently,
the
dogs
of
canine collaborators were, retired from
active duty.
Data Analysis
Activity Data
The
of
day.
influence of temporal and environmental factors (e.g.,
season,
temperature...)
upon
bear
activity
level
time
was
17
determined by assigning all non-active observations a numerical
of
"0"
and
probability
all active observations a value of "I."
of activity (from 0.0 to 1.0) for a
was calculated.
activity
or
Then
particular
value
the
mean
variable
Mean values of 0.5 indicated an equal probability of
inactivity
while values greater than or less
than
0.5
indicated probabilities of higher or lower activity, respectively.
SPSS
computer
statistical
(Anova)
level
programs were used for all initial breakdowns
analyses.
were
One-way
and
two-way
analyses
of
variance
differences
in
activity
and individual bear
effects.
used to test for significant
due to temporal,
environmental,
and
Tukey1s Honestly Significant Difference (HSD) test was used as a posthoc procedure to assess differences in individual means.
Community Site Data Analysis
Five
bears
(#15,
selected
for
a
activity
patterns
#38,
#50,
#59,and #76, Tables 2 and 3) were
more in-depth analysis of
(from
scats),
activity
the
interaction
monitoring),
food
and. habitat use (from aerial
between
habits
evidenced
by
community
site
conducted
as followups to bear relocations or whenever bear sign
analyses).
encountered in the field.
relocations
Community site analyses
were
sites
and
routinely
was
Only those community sites associated with
the five bears mentioned above were treated as follows.
remaining
(as
Data from all
were merged with existing IGBS data and
applied
to
other ongoing analyses.
Community
criteria:
site
"quality"
was
evaluated
according
to
three
food value, total understory cover, and understory species
I
18
diversity.
Food
value was determined by the density within the site of
22
most important bear food plants as determined from prior
of
IGBS community site and scat data,
handled separately.
items
was
also
1977-1982.
the
analysis
Animal matter
was
The relative food value, FV^, of each of these 22
previously determined
(Mattson,
in
prep.).
FV^
incorporates information on the following:
1.
Intrinsic energetic efficiency (EE^) of each item (subjective
evaluation
of
energy expended to acquire characteristic bite
volume
versus digestible energy per bite).
2.
Monthly food item preference, PF^, for item i :
PFi - (Vol1 / Freq1)/PFmax
where
Vol^ = % of total scat volume comprised of item i,
frequency
of
item
Freq^
i occurrence in scats of the sample and
maximum calculated value of (Vol^ /
=
%
^ max
=
Freq^).
-I
3.
group.
occur
Characteristic
) of a given
item
or
This value expresses the tendency of a particular diet item to
in
feeding
"contagiousness" (A^
aggregations.
more
The
efficiently
on
premise is that a bear is
a given item
if
it
capable
tends
to
of
occur
contagiously, as do certain root foods.
The relative food value of a given item is, then,
FV. = EE. x PF. x A."1
i
i
x
i
Since PF^ values were calculated by month, FV^ values likewise vary by
-I
month.
are
Tables of all the FV^,
given
in Tables 10 and 11.
EE^, PF^, and A^
values used herein
A more detailed derivation
parameter is available in Mattson (in prep.).
of
each
19
Individual
site,
(X ,
food values were then weighted by their cover at each
and summed to give the composite food value,
FV,
at each
community site:
FV =
Total understory cover,
adding
ZCFV1 x C1)
Cy , for each community site was found by
the cover class value for shrubs to the cover class value
for
herbs as recorded on the community site field forms (Appendix I).
The
resultant value enabled a rough comparison of cover between sites.
Understory species diversity,
Hyf was obtained by applying the
Shannon-Weaver diversity (information measure) index to all understory
species (shrubs and herbs) recorded on the community site forms.
All
species were included regardless of whether they were known bear foods
or not.
Hence:
= - s PiC1Oge Pi)
HU
where P1 = relative abundance (cover) of species i from O to 1.0.
Once the values for community site food value,
and
understory
sites,
these
understory cover,
species diversity were calculated for
three values were combined into a
single
all
community
quantitative
index of community site quality (CSQ).
First, each of the raw values for FV, C^, and
a
was converted to
proportional value by dividing by the maximum value.
For feedsite
x:
FV
X
C
u,x
H
u,x
= FV /FV
x
max
= C
/C
u,x u,max
H
u,x
/H
u ,max
Of these 3 variables food value (FV) was considered the most important
20
determinant of community site "quality," hence it was doubly
relative
to
cover
and diversity.
Therefore,
the
weighted
Community
Site
Quality index, CSQ, was found by:
CSQ
(FV
x 2) + (C
U
0X
)+(H
)
'
u,x
This expression was then proportionally adjusted to a 0.0-1.0 scale by
dividing by the maximum value.
For community site x:
CSQx - CSQxZCSQnax
Finally, the mean CSQ for all community sites ascribed to a given
bear was used for comparison with other bears.
Computer Relocation Habitat Scans
The
provided
community site analysis discussed in the
one
means of assessing the quality of habitat
individual bears.
which
for
As a second
section
occupied
by
approach, all of the radio relocations
occurred between the first and last days of activity monitoring
the primary study bears were subjected to an additional
richness" analysis.
Habitat
IGBS
foregoing
and
NPS
mapping
"habitat
Both aerial and ground relocations were included.
of Yellowstone National Park was
employees
from 1979 through
1982
conducted
according
by
to
the
classification system of Mueggler and Stewart (1980) and Steele et al.
(1979).
Several hundred plots were used to delineate habitat types on
airphotos. Resolution of the habitat mapping was roughly two hectares.
The
data
were transferred to 15 minute topographic quandrangle
maps
and subsequently digitized to facilitate computer analysis.
A spatial information computer software package was developed
Wm.
Hoskins for the IGBS to treat relocation habitat data.
by
As input.
21
this program receives the UTM coordinates for a given bear relocation.
It then generates a "scan circle" of 0.5 km radius with the relocation
point
as center.
This scan circle was used because most radio fixes
were obtained during the day and,
use
therefore, a description of habitat
based entirely on the immediate habitat in which
points
fell
the
would tend to overrepresent day bed sites.
relocation
The 0.5
radius partially corrects for this bias by incorporating not only
relocation
point
proper,
but also a broader area
surrounding
km
the
this
point through which the bear presumably entered or left the site.
Within
points
the scan circle,
a sampling grid is created with
every 88 m (for a total of ~101 points per scan circle).
each
scan circle,
type
is
the number of points falling within
output along with the amount of edge (E,
were
For
each
habitat
interface
between
adjacent habitats) occurring within the scan circle.
data
sample
pooled by season for each of the five bears
The scan circle
to
give
the
proportionate use of habitats by season.
The next step in this analysis was to rate the overall quality of
habitat
used
component
"unit
habitat type.
area
importance
by each bear according to the relative
importance
value
of
Mattson (in prep.) developed the concept of
values"
(IV^)
to
describe
of individual habitat types to Yellowstone
the
relative
bears.
incorporate information on characteristic food items found in
x,
each
IV^'s
habitat
the inherent food value of these items, the consistency with which
each
item is available in habitat x from year to year
flux
in availability),
(i.e.,
annual
the apparent preference toward habitat x
for
feeding on these food items (extrapolated from community site analysis
22
data)
arid the diversity of feeding opportunity in habitat x.
I
value of many food items varies according to phonological
the
IV 's
u
are
calculated
on a seasonal basis-
The IV 's
u
pertain only to the vegetative attributes of a habitat
matter is handled separately.
A
Since
stage,
used
type:
herein
animal
These IVu*s are tabulated in Table 12.
single "area food score" (FSq) was calculated for each of
the
five bears by multiplying the proportionate use of each habitat by the
corresponding seasonal IV
value.
FSa - S (Px>1n v u(Xji))
where
p
.
x, I
IVy ^x ^
is
the proportionate use of habitat x in
season
I
and
is the corresponding unit area importance value for habitat x
in season i.
The diversity of habitats within each scan circle was
calculated
using the Shannon-Weaver diversity index:
Hh = - E Px (IogePx )
where
px is the proportional representation of habitat x in the
circle.
The
mean value for Hh from all scan circles for a given bear
was used for comparisons.
was
also
parameters
scan
The mean amount of edge, E, per observation
calculated from the scan circle data.
described above (area food score,
Each
of
the
habitat diversity,
amount of edge) was adjusted to a 0.0-1.O scale by dividing the
three
and
value
for a given bear by the maximum value, so that for bear y:
»
= FS
/FS
a,y
a,y a,max
h,y
E
Hh,y^Hh,max
E /E
y max
The final step in the relocation data analysis was to combine the
23
three
parameters
relocation
habitat
described
above
into
a
single
expression
richness (RHR). The area food score
for
(FS)
was
given double weight so that for each bear:
RHR = (2 x FSa) + (E) +(H^)
The
resulting
values were again adjusted to a 0.0 to
dividing by the maximum value for RHR.
1.0
scale
by
For bear y:
RHR =RHR /RHR
y
y
max
Scat Data Analysis
Scats
for
the five primary study bears were analyzed
item content and diet item richness.
positively
ascribed
for
diet
Only those scats which could
to a particular bear were included.
These
be
were
generally collected at day beds or immediately following multi-bearing
radio fixes.
Each
scat was scored according to the energetic efficiency
pl8) of individual food items found in that scat.
"natural" (i.e.,
scat
was
non-garbage,
The EE^ for
see below) food item,
(EE,
every
i, found in the
weighted by the proportional volume of item i to
derive
a
Scat Value (SV):
SV =Z. (P1EEi)
where
p^
=
relative
proportion of item I in the
energetic efficiency for item I.
adjusted
the
scat
and
EE^ .=
The mean SV score for each bear was
to a 0.0-1.0 proportional scale by dividing the raw value by
maximum value (SV/SV^ax).
The adjusted values were then used
to
make inter-bear comparisons.
The percent by volume of digestible items (i.e.,
after deducting
24
volumes
of dirt,
groups (e.g.,
bear.
debris,
forb,
etc.) belonging in certain important
food
ungulate, shrub...) was also calculated for each
"Garbage" referred to any items of human origin and was treated
as "digestible" matter despite the obvious indigestibility of plastic,
etc.
Minimum Daily Movements and Home Range Estimates
Minimum
radio
daily movements Were calculated from
fixes.
were
used
this analysis.
underestimation
for
routes
those
and
an
This method
can
bears which tended to
result
in
forage
serious
over
then return to preferred bed sites
previous day's relocation.
as
daily
Both ground triangulation fixes and aerial relocations
in
circuitous
consecutive
long
near
the
Consequently, these data are best regarded
index of movement patterns rather than as an estimate
of
the
actual distance travelled.
Home range areas were calculated for the five primary study bears
for the period when they were monitored only.
determinant
Turner
of
1969).
Areas were based on the
the recapture point covariance matrix
(Jennrich
The areas thus obtained were not directly
comparable
since there was wide disparity in the length of the monitoring
for
the
#50).
was
five different bears (from 46 days for //15 to 150
To
facilitate inter-bear comparisons,
divided
estimate.
herein.
and
period
days
for
the area for each bear
by the number of relocations contributing
to
the
area
The resulting "area per relocation" is used for comparisons
4
25
RESULTS
Activity Data
Temperature
Activity
annual
data
were grouped into 5 C blocks and analyzed
and seasonal basis (Figures 2 and 3).
annually
temperature
level (p<.001).
on
Anova indicated
did have a significant effect on bear
an
that
activity
The temperature data yield a more-or-less bell-shaped
curve with a peak activity level in the 10-15 C range and low activity
at both temperature extremes.
at
temperatures
Tukey's HSD test showed that
activity
above 20 C was significantly lower than activity
in
the 5-20 G range (p<.05).
A
had
two-way Anova showed that jointly both season and
significant
variables).
temperature
main effects (as in the univariate Anova's for
both
There was also a significant interaction factor (p=.002)
indicating a significant difference in bears' responses to temperature
in
the
different seasons.
Since the majority of the
temperature
observations (71.0%) were collected during the summer, the temperature
histogram for summer (Figure 4) approximates the annual histogram with
high
activity
temperature
in
extreme
same general trend,
data
.PA
the 0-20 C range and lower
ranges.
activity
in
the
two
The fall data (Figure 5) followed
the
although the activity level was lower. The spring
(Figure 3) suggests a response opposite to the summer
and
fall
26
I-OO
.90
.80
U-
O
>-
.70
.60
•50
CD
<
CD
O
•40
•30
OC
O-
20
•
10
NO- OF RECORDS
7
-SC-OC
78
196
0C-5C
SC-1OC
182
119
10C-1SC
15C-20C
87
20C-25C
22
25C-30C
Figure 2. Relationship between temperature (in C) and probability of
bear activity. All temperature data from both monitoring
years are included.
%
OQ
<
CQ
O
Od
CL
NO- OF RECORDS
25
0C-5C
49
SC-1OC
16
IOC-1SC
II
15C-20C
Figure 3. Relationship between temperature (in C) and probability of
bear activity in spring (May). Temperature data from both
years are included.
27
Figure 4. Relationship between temperature (in C) and probability of
bear activity in summer (June-August). Temperature data from
both years are included.
I.00
.90
5
.80
.70
.60
.50
$
CD
O
0£
CL
.40
30
•
20
-10
NO. OF RECORDS
0C-5C
5C-10C
IOC-1SC
15C-20C
20C-25C
Figure 5. Relationship between temperature (in C) and probability of
bear activity in fall (September). Temperature data from
both years are included.
28
pattern:
activity
was greatest in the 0-5 C and 15-20 C ranges
and
much lower in the intermediate temperature ranges.
Precipitation and Ground Moisture
Sample
sizes
category.
Activity
categories
Anova,
were
(i.e.,
all
five
small
levels
for all but
were
lowest
precipitation
were
"no
for
rain and intermittent rain.
classes were
compared to the no-precipitation class.
bears
the
the
precipitation"
two
."raining"
Figure 6).
grouped
For
the
together
and
This analysis indicated that
significantly less active during precipitation than
there was no precipitation (p=.0032).
The response to
when
precipitation
was partially temperature-dependent, with greater activity during rain
at
was
warm (>10 C) temperatures than at colder (<5 C)
also
temperatures.
noted that bears tended to increase their activity
onset of a rain storm as if briefly agitated,
quickly tapered down.
at
It
the
and then their activity
The amount of agitation seemed to be correlated
with severity of the storm.
Ground
(p=.0431,
and
moisture
Figure 7).
had
a
significant
effect
on
HSD
post-hoc
activity
Bears were most active when the ground was dry
about equally active when the ground was moist or
Tukey1s
bear
procedure
showed
that
no
wet.
two
However,
groups
were
significantly different at the .05 probability level.
Wind Speed
Anova revealed significant differences in bear activity levels at;
different
wind speeds Cp=ZOlS,
Figure 8);
however,
the differences
were relatively minor and it is doubtful that they reflect
legitimate
29
I OO
NO. OF RECORDS
717
NO PREClP
22
MISTING
22
RAINING
54
INTERMlTTANT
RAIN
10
SNOW/HAIL
Figure 6. Relationship between precipitation type and probability of
bear activity. All precipitation data from both monitoring
years are included.
>- I-OO
OF RECORDS
577
DRY
86
MOIST
157
WET
6
SNOW
TRACE
Figure 7. Relationship between ground moisture and probability of bear
activity. All ground moisture data from both monitoring
years are included.
30
biological
variation.
Tukey's
HSD
test showed that no
differed significantly at the .05 probability level.
two
groups
This result may
relate partially to unequal sample sizes since the range
(differences
in means) required for significant differences in Tukey's test becomes
larger with disparate sample sizes.
Cloud Cover
Anova
indicated
that bear activity differed significantly
with
different degrees of cloud cover (p=t.009. Figure 9), but, as with wind
speed,
the
differences
persuasive.
were
not great enough
to
be
biologically
Tukey's HSD test indicated that bears were significantly
less active when it was overcast than when the cloud cover was 10%
or
less (p<-05).
Seasonal and Monthly Effects
Seasonal
activity data were very limited.
The earliest
spring
observations, were roughly 45 days after den emergence and the
fall
observations
entrance
and
date.
were
made about 30 days before
the
latest,
average
den
Thus, * the activity patterns described below for May
September may not accurately represent the activity
program
for
all of spring and fall, respectively.
Anova
activity
demonstrated
levels
(Figure 10).
by
a
highly
month (p<.001).
significant
difference
in
bear
Activity was highest
in
July
The activity level in July and August was significantly
higher than activity in May or September (p<.05).
31
Lu
O
5
OD
O
(XL
O-
NO. OF RECORDS
62
NO WIND
491
162
0 - 5
5-10
93
10-20
10
20* »ph
Figure 8. Relationship between wind speed (in km/hr) and probability
of bear activity. All wind speed data from both monitoring
years are included.
1 .00
.90
.80
%
.70
065
067
60
0.55
.50
CD
<
.40
CD
30
Q-
20
O
CC
10
NO. OF RECORDS
259
10% OR LESS
SKY COVER
220
SCATTERED
CLOUDS
97
BROKEN
CLOUDS
239
OVERCAST
Figure 9. Relationship between cloud cover and probability of bear
activity. All cloud cover data from both monitoring years
are included. (Scattered clouds - 10-50% cloudy, broken
clouds = 60-90% cloudy, overcast = >90% cloudy.)
32
Time of Day Effects
Annual Activity Patterns
The four diel time periods were defined as follows:
sunrise=
diurnal=
sunset=
nocturnal=
Annually
one
one
one
one
hour before to one hour after sunrise
hour after sunrise to one hour before sunset
hour before sunset to one hour after sunset
hour after sunset to one hour before sunrise
there was a highly significant difference
(p<=001)
bear activity levels at different times of day (Figure 11).
hoc
procedure
active
They
during
were
revealed
that bears were significantly
the day than during the other
most
active
during
the
two
three
The post-
(p=.05)
diel
crepuscular
in
less
divisions.
periods
with
significantly greater activity at sunset than at night (p<.05).
Bears
also displayed highly significant differences in
activity
level according to hour of the day (p<.001, Figure 12). There were two
primary
period
activity
of
afternoon.
Bears
peaks at 0500 and 2200 h (MDT) with an
significantly
early
to
often
went through a transition phase
of
brief
erratic
This phase usually lasted from 15 minutes to
hour depending on the individual bear and seemingly represented
period
active.
of
mid
The lowest overall activity was at 1500 h.
activity in the evening.
an
(p<.05) lower activity from
intervening
restlessness or agitation prior to
becoming
a
consistently
Schleyer (1983) described a similar "winding up" interval for
his study bears in Yellowstone.
33
Figure 10. Relationship between month and and the probability of bear
activity. Data from all bears and from both monitoring
years are included.
Spring
Summer
F= II
Yearly Ave
SUNRISE
DIURNAL
SUNSET
NOCTURNAL
Figure 11. Relationship between diel period and probability of bear
activity annually and seasonally. Data from all bears and
from both monitoring years are included.
P r o b a b i I it y
o
f Ac t i v i Iy
I.00
.90
.80
.70
60
50
.40
LU
30
20
-10
Ti me
of
Day
( M• D . T .)
Legend
Al I
Bears
Figure 12. Probability of bear activity according to hour of the day annually. Data from all bears and
from both monitoring years are included.
35
Seasonal Activity Patterns by Diel Period
Univariate
and
season
levels
Anovas indicated that both time of day (dial
individually
had significant effects
(p<.001 for both variables).
on
period)
bear
activity
A two-way Anova supported
these
results and showed that jointly time of day and season had significant
effects
(p<.001)
on
activity
and that
there
was
no
interaction
(p=.219).
Bears
period
tended
of
(Figure
to be crepuscular in all three
seasons,
greatest and least activity varied by season.
11),
bears were about equally active at sunrise
but
the
In
spring
and
sunset
(mean probability of activity, x,=.80 and .82, respectively) and least
active at night (x=.38).
The morning peak occurred at 0600 h and the
evening peak at 2000-2200 h (Figure 13).
low
during
both
day
and night,
Bear activity was relatively
but a brief
period
of
increased
activity occurred around 1100 h.
In summer, bears were most active at sunrise (x=.94)
active during the day (x=.60).
Activity peaks occurred from 0400-0700
h and from 2100-2200 h (Figure 14).
(x=.32),
but
generally
bears
became
were
active
The lowest activity was at 1500 h
often active even
from 1600-1700
h
at
with
this
activity
spring and fall.
patterns
time.
activity
increasing until the late evening peak noted above.
grizzlies’
and least
were less erratic in
Bears
steadily
On the whole, the
summer
than
in
Non-active periods were less likely to be punctuated
by periodic spurts of activity and, once they became active, grizzlies
tended
to
remain active for longer periods.
Some of this
"evening
out" effect was probably due to the greater sample size, in' summer.
In
Probabi I ity
of
Activity
I
-00
■90
•80
•70
•60
50
-40
W
Ox
■30
■
20
•I0
Ti me
of
Day
(M. D . I . )
Legend
All
igure 13. Probability
Bcors- . - Spr i ng
of bear activity according to hour of
bears and from both mbnitoring years are included.
the day in spring (May).
Data from
all
Probebi I i t y
of
Activity
I - OO
90
■80
■70
■60
50
•40
30
w
>4
20
•I0
o
O
§
O
O
O
O
ro
o
o
O
B
I
O
O
O
O
Oo
O
U)
-
o
O O O
I im e
of
V
o
rv
U~
A
Ol
<
r-\ f
\
«7>
v
z
v
V\ w
o
o
o
o
o
o
Day
-X
a>
U
Oo
o
o
ro
u
o
o
iv
A
O
O
(M.D.T.)
Legend
AM
Bears - - Summer
Figure 14. Probability
of bear activity according to hour of the day in summer ( J u n -Aug).
all bears and from both monitoring years are included.
Data
from
38
fall,
grizzlies
during
the
grizzlies
Activity
day
were most active at sunset (x=.71) and least
(x=.44,
Figure
11).
Unlike
spring
wete not highly active at sunrise during the
active
and
summer,
fall (x=.46).
was lowest from 1300-1700 h in early afternoon (Figure
15).
Grizzlies became active beginning around 1800 h and activity reached a
peak
from 2200-2300 h.
during
The drastic activity oscillations
indicated
the late night (Figure 15) are probably attributable to
sample size rather than to actual shifts in bear
behavior.
small
Activity
quickly tapered down after 1000 h.
Individual Bear Patterns
Anova
revealed
a
significant difference in the
level of the different study bears (p<.001.
procedure,
Tukey's HSD test,
mean
Figure 16).
activity
The post-hoc
showed that the mean activity level
of
bears #50 and #38 was significantly lower than the mean activity level
of bears #59 and #76.
The
activity level of individual bears varied according to
period (Figures 17 and 18).
period
had
significant
significant
indicating
main effects (p<.001).
interaction
that
In a two-way Anova,
(p=.007)
between
both bear and
There
these
was
two
individuals behaved differently over the
diel
diel
also
a
variables
four
diel
time periods.
All
of the five primary study bears were least active during the
day (Figures 17 and 18).
All but #15 were also highly active
both crepuscular periods.
Three of the bears (#15, #38, and #76) were
most active at sunrise.
during
Bear 50 was most active at sunset and Bear 59
Probability
of
Activi ty
I .00
90
80
.70
60
•
50
•40
•
UJ
VD
30
20
•
10
2400
Time
of
Day
( M •D •T .)
Legend
AI I
Bears - • Fal I
Figure 15. Probability of bear activity according to hour of the day in fall (Sep).
bears and from both monitoring years are included.
Data
from
all
40
I-00
NO. OF RECORDS
172
168
12*
44
80
BEAR «38 BEAR »50 BEAR »76 BEAR »59 BEAR »15
Figure 16. Overall probability of activity for the five primary study
bears. All activity records from each bear are included.
All Beers
Beer *76
Beer *59
SUNRISE
DIURNAL
SUNSET
NOCTURNAL
Figure 17. Probability of activity according to diel period for all
monitored bears (including all activity records from all
bears for both monitoring years) and for primary study
bears #76 and #59.
41
was
active
every
time
she was sampled except
during
the
diurnal
period.
The activity pattern of grizzly #15 departed from the usual trend
in several respects.
He was much less active at sunset than any other
bear and more active at night than any other bear except #59.
showed lower than average activity during the day.
data
(or
He also
Schleyer's (1983)
likewise indicated that the activity level of #15 was less
equal to) the activity level of all other bears for
and sunset periods.
the
than
diurnal
However, his data did not indicate unusually high
activity for #15 at night.
Bear
#50
(Figure
19).
pattern
of
was the only grizzly with data from all three
During
high
spring and fall,
crepuscular activity.
she adhered
In
summer,
seasons
to
the
normal
she
was
more
nocturnal than in the other seasons.
Bear
Bear
Bear
If 5 0
*38
*15
I .in
——— —.——.
SUNRISE
DIURNAL
SUNSET
Figure 18. Probability of activity according to
primary study bears #50, #38, and #15.
NOCTURNAL
diel
period
for
42
Spring
Summer
Fall
Yearly Ave
SUNRISE
DIURNAL
SUNSET
NOCTURNAL
Figure 19. Probability of activity according to diel period for
50 annually and by season.
Bear
Community Site Analysis
Values for community site food value (FV), total understory cover
(C^),
understory
(CSQ) for
are
all
species diversity (Uu )»
communitysites
given inTable 13.
and community site quality
ascribed
to the five primarystudy bears
Mean values for each of these parameters
are
given in Table 4.
Bear
the
38 had the highest
five bears.
densities
sites.
Her
mean CSQ (proportional value
high FV value resulted
of grasses and sedges at most of her
primarily
relocation
of 1.00) of
from
high
community
Mean understory cover was also highest for Bear 38.
Bear 76 had a mean CSQ value of .99, only slightly below that for
//38.
Like Bear 38,
high densities of grasses,
sedges, and forbs at
43
most
of
community
#76's
sites accounted for the high
FV
and
CSQ
values.
Table 4. Mean values for Food Value (FV), Understory Cover
(C)9
Understory Species Diversity ( H ) 9 and Community Site Quality
Index (CSQ) for Bears 15,38^50,59, and 76. Values for
individual community sites are given in Table 13.
Bear #
n
FV
C
15
38
50
59
76
4
8
5
5
3
Bear
widely.
59
.38
.67
.41
. .59
.69
.53
.70
.50
.53
.62
.67
.64
.63
.68
.66
had the median CSQ value (.89).
Several
CSQ
Hu
U
.73
1.00
.73
.89
.99
Her FV
sites had medium to high densities
scores
of
varied
graminoids.
V
Whitebark
sites;
(see
pine
nuts
however,
Table
feeding
on
were available at two of
pine
# 5 9 -s
July
nuts are only of moderate value in
community
mid-summer
11),
and there was no direct evidence that Bear
pine
nuts
at that
time.
understory diversity of the five bears,
#59
had
the
59
highest
was
mean
testament to the wide variety
of feeding opportunity in the mesic meadows along Antelope Creek.
Bears
bears
15
and 50 had equivalent mean CSQ values
of
.73.
tended to occupy sites with a lodgepole overstory and a
understory
barren
of most
important
forage
species.
Both
sparse
Grass/sedge
density was very low at all but one of #15*s sites and low to moderate
at all of #50's sites.
Bear foods at #15's community sites consisted
primarily of graminoids and mixed forbs.
more
plentiful
at
#5'0's sites,
Forage species were slightly
consisting of
grouse
whortleberry
44
(Vacclnium
scoparium),
several
tuberous
species
(Claytonia
and
Lomatium) and various forbs and grasses.
Relocation Habitat Scans
Bear
primary
76 received the highest area food score (FSq) of
study bears (Table 5).
the
five
Most of the relocations for #76
were
made in the Blacktail Plateau area southwest of Tower Falls and in the
western
portion of the Washburn Range.
The habitats occurring
most
frequently in these relocation circle scans were ABLA/VASC-PIAL (35%),
.FEID/AGCA-GEVI
(24%),
and ABLA/VASC-VASC (18.5%).
Bear 76 received
the highest scores for mean habitat diversity (H^) and mean amount
edge
was
per relocation (E).
higher
than
of
Her relocation habitat richness (RHR) score
any other bear's,
primarily as
a
result
of
her
exceptionally high FSq score.
Table 5. Grizzly bear Area Food Scores (FS ), mean amount of Edge per
relocation scan circle (E), mean Habitat Diversity in scan
circles (H, ), and Relocation Habitat Richness scores (RHR).
All values" calculated from 0.5 km radius computer scan
circles around bear relocation points. Both raw values and
adjusted (proportional) values (in parentheses) are given.
FS
Bear
0.0210
14.1688
11.1243
17.5651
27.1866
15
38
50
59
76
Bear
The
E
aL
(.001)
(.520)
(.409)
(.646)
(1.00)
671.4
1401.1
939.2
2114.6
1662.3
RHR
5H
(.32)
(.66)
(.44)
(1.0)
(.79)
0.23
0.55
0.39
0.70
0.61
(.33)
(.79)
(.56)
(1.0)
(.87)
0.652
2.490
1.818
3.292
3.660
(.18)
(.68)
(.50)
(.90)
(1.0)
59 received the second highest RHR score of the five bears.
habitats with the highest frequencies in the scan
ABLA/THOC (23%),
circles
ARTR/FEID-GEVI (20%),. and ABLA/VASC-VASC (18%).
were
The
45
ABLA/VASC-PIAL
values,
and ABLA/CACA habitats,
'also
had
high frequencies.
both of which have
Bear 59 received
high
the
IV
highest
scores for habitat diversity and mean edge per relocation.
Bear 38 received the median RHR score.
most
frequently
PICO/PUTR
in her scan circles were ABLA/VASC-CARU
(25%),
FEID/AGCA-GEVI
The habitats represented
and the PSME/CARU (15%).
The
the
ARTR/FEID-GEVI
habitats were also well represented.
median value for area food score,
(25%),
habitat diversity,
and
Bear 38 had the
and edge
among
the five bears.
Bear
50
had a relatively low RHR score
(Table 5).
The
three
habitats occurring most frequently in her scan circles were ABLA/VASCVASC
(59%),
second
ABLA/CARU (16%),
lowest
and ABLA/CAGE (15%).
values for area food
score,
habitat
Bear 50 had the
diversity,
and
amount of edge.
Bear 15 had the lowest RHR value of the five bears as well as the
lowest
value for the other three estimates
(Table 5).
Eighty-seven
percent of the habitat in his scan circles was PICO/PUTR habitat
with
IV
scores
respectively.
of
only
Eighteen
entirely PICO/PUTR— hence,
of
.038
and
.003
(FSq)
feeding
that
the very low scores for habitat
plateau
and
microsites
scattered
were
Bear 15's abysmal area food
Field.observations
throughout
the
vast
the
indicated
lodgepole
around Hebgen Lake had a somewhat richer understory than
area at large.
fall,
diversity
of .001 (relative value) may slightly underestimate
opportunity within his range..
moister
summer
the twenty-six point scans for #15
and mean amount of edge per scan circles.
score
in
type
the
Nonetheless, the overall characterization of Bear 15's
46
range derived from the RHR estimate is consistent with the
observer's
impressions that the area was vegetatively depauperate.
Scat Analysis
Scats from four bears,
Scat
Value
analysis;
#15, #38, #50, and #59, were used for the
£he sample size for Bear 76 was too
small
to
reliably indicate her food habits.
Bear
59
Sixty-one
had
percent
comprised
of
both
microsites.
of
forbs
representations
(13%),
the highest mean SV of the four
were
of
the "digestible" scat volume
(Table
7).
Claytonia
which
The
scats
forbs
typically
occur
(Table 6).
(see
with
the
lanceolata (16%) and
p.24)
Lomatium
contagiously
in
and
was
highest
spp.
specific
Grasses and sedges comprised 34% of the scat volume
were found in 88% of the scats sampled.
59's
bears
and
There was no garbage in Bear
meat accounted for only 2% of
the
digestible
scat
volume.
Table 6. Mean Scat Values (SV) scores for the primary study bears.
Both raw values and adjusted (proportional) values (in
parentheses) are given.
Bear #
n
15
38
50
59
6
12
15
17
SV
0.323
0.505
0.533
0.571
(0.57)
(0.88)
(0.93)
(1.00)
47
Table 7. Scat
summary
for
primary
study
bears:
percent
"digestible” diet volume and percent frequency occurrence for
important diet item groups.
Grass/
sedge
Forbs
Root
Shrub
Garbage
Meat
Bear 15
(n=6)
% Vol.J
% Freq.
14.6
66.7
4.2
16.7
45.8
66.7
27.1
33.3
Bear 38
(n=12)
% Vol.
% Freq.
76.1
100.0
8.0
25.0
0.5
8.3
3.4
16.7
Bear 50
(n=15)
% Vol.
% Freq.'
8.1
26.7
16.2
20.0
48.4
60.0
Bear 59
(n=17)
% Vol.
% Freq.
33.9
88.2
1 % Volume= {(Total
%
19.0
33.3
61.1
82.3
0.6
5.9
1.9
5.9
Item i) / [(nxlOO)-(Total
%
Debris,etc.)]} x 100
2 % Freq= {(Number of scats containing Item i) / (Tot. # scats)} x 100
Bear
50 had the second highest SV score of the four bears.
diet was quite unlike that of #59,
the
digestible
remaining
however.
Forty-eight percent
scat volume was meat of which 5% was rodent
43%
was ungulate.
Her
Ungulate meat has one of
and
the
of
the
highest
energetic efficiency (EE^) values of any bear food (Table 10). Sixteen
percent
of
the scat volume was garbage or human refuse of some
sort
presumably discarded by hikers and fishermen along Nez Perce Creek and
in
the
Geyser
vegetation:
ursi)
Basin.
19%
Twenty-seven
percent
shrub (Vaccinium scoparium and
and 8% grass/sedge.
of
the
volume
Arctostaphylos
relocation
(Recall
that
habitat
both
richness
(RHR)
scores
discussed
of these expressions pertain only to
components of an area.)
uva-
The relative absence of vegetative matter
in #50's diet is consistent with the low community site quality
and
was
the
(CSQ)
earlier.
floral
48
Bear 38 fed primarily on grasses and sedges (76%) and forbs
during this study.
Animal
matter
digestible
(8%)
Gfaminoids appeared in all 12 scats of the sample.
(trout
and ungulates) accounted for only
scat volume.
3%
of
the
The relatively high SV score of .88 for #38
reflects the high EE^ value of the graminoids.
The
scat
sample
for Bear 15
included
only
six
scats. Six
additional scats were not collected in the field because they appeared
to consist of nothing but indigestible plastic and trash.
obtained
his
from
The results
#15's scat analysis accord well with other indices
activities (from dog tracking,
and
data).
bears.
He also had the highest volume of garbage (46% of "digestible"
volume
and
sites
scat
frequency of 67%) of any bear.
obtained from the resorts,
around
mammal)
15 had the lowest SV score (.57)
had
digestible
residential
Hebgen Lake and Duck Creek.
a
scat
of
previous
years'
readily
Bear
movement patterns,
of
Human
areas,
four
refuse
and
Graminoids and forbs .had
27%
was
fishing
Meat (ungulate and
scat frequency of 33% and accounted for
volume.
the
large
of
the
relatively
low
volumes, comprising 15% and 4%, respectively.
Movements and Home Range Use
Minimum
from
2.7 km for Bear 59 to 5.9 km for Bear 50 (Table 8).
home ranges,
from
daily movements for the five primary study bears
4.90
Correlations
ranged.
Short
term
as expressed as the "area per relocation" (p.24), ranged
sq km for Bear 59 to 23.13 sq km for Bear 38
(Table
9).
between movement patterns and home range use are treated
in the discussion section.
49
Table 8. Consecutive
minimum
daily
five primary study bears.
Bear #
n
15
38
50
59
76
15
5
7
16
9
movements
(km)
for
the
Minimum
Movement
4.1
4.8
5.9
2.7
5.1
Table 9. Short term home ranges for the primary study bears. Areas
derived from method of Jennrich and Turner (1969)
as
calculated from all relocations between first and last days
of activity monitoring for each bear. "Area per relocation"
values (see p. 24) are used for comparisons herein.
Bear #
n
Total Area
(sq km)
Area per Relocation
(sq km)
333.25
485.81
335.58
161.58
322.06
12.34
23.13
7.99
4.90
11.10
27
21
42
33
29
15
38
50
59
76
Tracking Grizzlies with Bear Dogs
Trained bear dogs were capable of accurately tracking
bears
for distances up to 15 km.
Intermittent bear sign (tracks
scats) verified that they were on course.
hounds
led
would
have
us directly to digs,
been
extremely
individual
In several instances,
day beds,
difficult
to
or other activity
locate
without
or
the
which
their
assistance.
To
was
better illustrate,
one tracking session during which Bear 15
followed will be described in detail.
On
July
15,1981,
radio
50
triangulation placed #15 bedded in dense willows south of the Grayling
Arm
of Hebgen Lake.
The following morning there was no signal
him in that vicinity,
dogs.
and
so the tracking party entered the area with the
The dogs soon located #15's day bed from the previous afternoon
began tracking him through the willows.
followed
stopped
a
convoluted
The grizzly's
route through very
dense
possibly
bedded
Twice
scat.
he
At
he appeared to have rolled around in the grass or
down briefly.
The bear crossed Duck
wide)
several times while moving through the willows.
along
adjacent
dirt roads and cattle trails (where his
very apparent) for distances up to I km.
stretches.
foraging
brush.
at isolated lodgepole "islands" and left a single
one of these sites,
these
from
Creek
He
(~10 m
travelled
tracks
were
More scats were found along
Bear 15 eventually crossed Hwy. 191 and entered
xeric lodgepole area.
He followed a logging road through a
a
recently
cut area and soon arrived at the primary road into a residential area.
Here he walked along a driveway passing within 30 m of one home, waded
across a nearby pond and headed north.
recrossed
this
the highway by Grayling Creek.
point at 2:30 that morning.
He travelled over a ridge and
A grizzly was observed
at
He then crossed Grayling Creek and
headed south, again leaving a scat and signs of feeding activity along
the way. .
By the time the tracking session had progressed this far,
it was
mid-afternoon and the hounds had a difficult time following the trail.
Subsequent radio triangulation placed #15 along Cougar Creek,
km
south
of our last reliable
dog-assisted
location.
about 4
Consecutive
daily radio fixes would have estimated that #15 had moved a minimum of
51
7.6 km,
whereas
dog
tracking indicated that #15 travelled at
least
15.03 km.
t
52
DISCUSSION
Activity Patterns
Diel Patterns
Grizzlies
were primarily crepuscular and nocturnal in this as in
most other studies of grizzly bear activity patterns.
Craighead
Pearson
early
Craighead
(1965) reported that Yellowstone grizzlies were
nocturnal.
(1975) found that Canadian grizzlies were most active in
morning,
(1983)
late afternoon to evening,
and at
and
night.
the
Schleyer
described nocturnal activity for four of his study bears while
the fifth,
an older male, was primarily diurnal.
His annual activity
peaks of 0630 and 2400 correspond closely to my observed peaks of 0530
and
2300.
None
of the grizzlies in my study could be
regarded
as
"diurnal."
The
literature
perturbations
observed
diurnal
reported
of
that
in
spring/summer
bear
diel
Yellowstone
spring
that
provides
no consensus
activity
regarding
patterns.
grizzlies were less
and fall than
during
seasonal
Schleyer
nocturnal
summer.
grizzlies were more active at night
(March
the
(1983)
and
more
Sizemore
than
(1980)
day
during
through July) but all bears were active at
all
hours of the day during summer/fall (August until den entrance).
This
and
study found that crepuscular activity was
nocturnal
described
activity lowest in spring,
most
pronounced
a pattern similar to
by Garshelis and Pelton (1980) for Tennessee
black
that
bears.
53
Like
the grizzlies in Schleyer's study (1983),
were
less
contrast
grizzlies in my study
nocturnal in spring and fall than during
to
his results,
summer
but,
diurnal activity was also lower
in
in
these
seasons.
Although
nocturnal,
all
there
magnitude
of
bear
diel
does
result
in
and
during
the
I believe that the disparity, as described above, for
reflects
differences
and/or
was considerable variation between the bears in the
primarily
not
crepuscular
activity during the four dial periods
three seasons.
grizzly
of the bears in my study were
activity
patterns
from
one
study
individual differences in the bears
merely from contrasting
sampling
activity patterns seem to arise from
to
another
sampled
schemes.
and
These
individual
and
regional variation in food habits and habitat use and secondarily from
I
differences
probably
in
sex,
legitimate
age class,
to
claim
that
to
reproductive
status.
grizzlies
in
a
extent,
lesser
It
Yellowstone
is
are
predominantly
crepuscular
However,
due
to
attempts
to describe peak activity times by hour or diel period on
the
and,
and
considerable degree of
nocturnal.
inter-bear
variation,
a
seasonal basis may not be particularly meaningful.
Seasonal Activity Levels
Garshelis and Felton (1980) found that Tennessee black bears were
inactive
emergence.
peak
until
in
most
of
the
Thereafter,
June,
time during
the
March,
the
month
after
activity level steadily increased to
remained high through September,
den entrance.
first
and then
a
decreased
They postulated that the low activity level
in
54
spring was related to high use of grasses and sedges
easily
obtained,
were
levels of activity.
which,
energetically insufficient to
although
maintain
high
Increased activity in summer was associated with
breeding activity and foraging on berries and fruits— foods which were
difficult to obtain but of high caloric value.
level
The moderate activity
in fall was due to the necessary pre-denning weight gain and to
patchier food distribution which required increased searching.
Schleyer (1983) found that in Yellowstone,
grizzly bear activity
increased from March to an overall peak in May (although he
that
this peak may have resulted from a sampling
bias).
cautioned
Seasonally,
his bears were most active during the summer and least active in fall.
Sizemore
(1980)
reported that grizzlies were more.active during
the
late summer/fall period than during the spring/early summer period.
Grizzly
equally
above
active
studies
represented
were
bears
probably
in spring and fall.
are
by
in my study were most active in summer and
not
(Monthly comparisons
possible since spring
a single month.)
and
Low activity levels
related to high use of
ungulate
with
fall
were
during
carrion
about
the
each
spring
(Cole 1972;
Craighead and Sumner 1982; Knight et al. 1984). Schleyer reported that
bears
were
significantly less active while using a carcass
other times,.
activity
al.
in summer is due in part to breeding activity ahd in part to
1980;
Knight et al.
1984).
1984;
(Mealey 1975;
Knight
Reduced activity levels during
autumn correspond to increased use of pine nuts
et al.
at
As described above for Tennessee black bears, increased
time-intensive foraging on grand.noids and forbs
et
than
(Mealey 1975;
Knight
Kendall 1981) and, to a lesser extent, increased use of
55
ungulates.
Both
sources which,
days.
one
nuts
and meat
provide
once located or captured,
concentrated
and
concomitant
prolonged
energy
can be utilized for several
This explanation is not entirely satisfactory,
might
huts
pine
however, since
expect that even when high energy diet items such as
pine
ungulates
gain
with
are
the
feeding
available,
pre-hibernation
the
requisite
period
weight
would
necessitate
bouts and hence elevated activity levels right
up
until the onset of "pre-hibernation lethargy" (Craighead and Craighead
1972).
Futhermore, since most qf the meat which appears in fall scats
.
is acquired by predation,
'
some increases in activity associated
with
the search and kill might be expected.
Environmental (Weather) Effects
There
are
a number of ways in which weather factors can
bear activity levels.
stress
which
behavior.
maintain
bears,
can
Moen
environment
by
an
,
Unfavorable conditions may induce discomfort or
be mitigated by remaining
inactive
or
adjusting
(1973) described how ungulates react to the
making physiological and
behavioral
internal state at or near the optimal
thermal
adjustments
condition.
the situation is complicated somewhat by the fact that
internal
miIeau
varies
according
physiological/metabolic phases (hibernation,
transition,
al.
affect
normal activity,
(1983).
Much
to
four
and
With
bears’
discrete
"walking hibernation" or
hyperphagia) as described by Nelson, et
of the observed seasonal variation in response to
environmental factors assumedIy relates to these phases.
Garsheliq
to
Pelton
(1980) suggested that black
bears
For example,
were
less
56
sensitive
to
temperature in the fall because
their
"preoccupation"
with foraging (hyperphagia phase) suppressed temperature effects.
Certain environmental conditions might influence the
of
foraging
affecting
success,
the
either
probability
by affecting the prey directly
bears* ability to detect or
capture
the
or
prey.
by
Any
factor which augments or interferes with a bear's sensory capabilities
should affect activity in this fashion.
Unfortunately,
reliance
Bear
on
not
a
great
the distance senses in grizzly bear
auditory
capabilities
are
experimental evidence is lacking.
Burghardt
deal is known about
1977)
reported
that
reputed
Kuckuk (1937,
captive
brown
auditory signals at a distance of 15 meters.
in
to
foraging
be
and their harems,
importance.
that
Bacon
these
two
behavior.
although
cited in Pruitt and
bears
responded
to
Grizzlies preying on elk
locate
bugling
but vision and olfaction are of much greater
(1973) and Bacon and Burghardt (1976a)
senses
relative
good
the fall might rely partially on auditory cues to
bulls
the
were highly
coordinated
in
concluded
bear
foraging
behavior.
Recent
studies have indicated that bear vision
better than once believed.
is
considerably
Although nearsighted, black bears are able
to distinguish color hues and to discriminate between simple geometric
forms (Burghardt 1975;
well-developed
fairly
keen
Garshelis
during
and
Bacon and Burghardt 1976b).
The presence of a
tapetum lucidum indicates that bears* night vision
(Bacon and Burghardt
1976b;
Cloudsley-Thompson
Pelton (1980) suggested that while feeding on
late summer,
black bears rely on color vision to
is
1961).
berries
locate
and
57
select
was
berries.
They felt that increased nocturnal activity in fall
related to feeding on acorns which,
unlike berries,
were
large
enough to be seen at night.
In general,
different
However,
visual stimuli are subject to less variability under
environmental
conditions
than
are
olfactory
stimuli.
such factors as cloud cover and lunar phase which affect the
degree of illumination might affect grizzlies' visual perceptions and,
consequently,
their
activity
patterns.
This
study
found
that
grizzlies
did tend to be least active when the sky was overcast,
Garshelis
and Pelton (1980) reported that black bear activity
were not related to cloud cover.
on
test
stimuli
discriminate
did
hues
but
levels
Varying the degree of sun and shade
not interfere with
(Burghardt 1975;
black
Bacon
and
bears'
ability
to
Burghardt 1976b).
Schleyer (1983) examined the effect of lunar phase bn grizzly activity
and
found
that grizzlies were most active under
conditions.
them
intermediate
light
He noted that grizzly eyesight did not appear to confine
to activity under maximum light conditions,
such as daytime
or
under a full moon.
Olfaction
bear;
is
however,
(Russell 1979;
distances
considered to be highly developed in
most
of the supporting evidence is purely
Murie 1981).
Grizzlies
in
often
travel
grizzly
anecdotal
considerable
to ungulate carrion and their movement seems to be directed
by scent (Craighead and Mitchell 1982).
role
the
the
success
(Schleyer, pers. comm.).
of
Nuances of scent play a major
grizzly
Kuckuk (1937)
trapping
operations
observed that captive
bears relied primarily on olfaction to locate hidden foods.
brown
58
Wright (1982)
which
police
searching,
described two distinct,
dogs use
are
olfaction.
analogous
olfaction while foraging.
a
mobile
prey
to
These
processes,
by
tracking
the ways in which bears
might
and
employ
"Tracking" refers to following the route of
by cueing on either the residual scent
itself or on the scent of disturbed earth,
by the prey.
but related processes
of
the
prey
crushed plants, etc., left
Bears may sometimes locate ungulates and other mammalian
prey
in this fashion.
bear
detects
and
"Searching" refers to the process by which
locates a stationary food
item
by
following
a
an
airborne scent trail to its source.
Both olfactory processes, tracking and searching, can be affected
by ambient conditions.
by
Budgett (1935),
Wright (1982), relying heavily on earlier work
described
might influence olfaction.
how various
environmental
conditions
Although much of his analysis pertained to
tracking mobile prey, most of the effects he described should apply to
search situations as well.
Moisture,
strength
and
accumulate
whether
airborne
longevity
of
or on the ground,
scent.
Oily components
can
affect
of
the
the
scent
on moisture droplets and thus expose a larger surface
for
evaporation.
Thus, based on olfactory criteria alone, grizzlies would
be
to
expected
relative
be more active than average in
humidity,
Conversely,
heavy
light
rain
rain
or moist ground
conditions
following
will tend to wash the scent off
of
of
a
high
rain.
exposed
surfaces and will create a negative effect for olfaction.
Schleyer's (1983) observations are consistent with the
effects of moisture on olfaction.
predicted
He found that as relative humidity
59
increased,
finding
to
grizzlies
than
grizzly
bear activity increased,
olfactory
were
average
enhancement.
and he attributed
Schleyer
also
reported
more active than average during rain and less
when
there
was
no
rain.
this
Precipitaion
that
active
exceeding
1.4 cm/day did inhibit activity in his study.
Contrary
to
the predictions,
in my study grizzly activity
depressed
during rain and somewhat higher (no significance at
when
ground was dry.
the
Tennessee
Garshelis and
Pelton (1980)
p=.05)
found
to
avoid physical discomfort.
below
temperatures.
high
is
7 C depressed activity more than rain
Similarly,
in
my study,
bear activity
correct
more
for
striking if daytime
observations
Rain at
at
higher
during
rain
and 0.73 at 10.1 C and higher.
on
This relationship
are
excluded
the low activity during the diurnal period).
activity during rain then becomes 0.40
moisture
noted
from a mean probablity of .46 at temperatures of 0-5 C to a
of .54 at temperatures of 10.1 C and higher.
still
bears'
Garshelis and Pelton
that the response to precipitation was temperature dependent.
temperatures
but
In these latter two studies,
diminished activity during precipitaion may have resulted from
increased
that
black bears were active less than average during rain,
activity increased shortly after a rain.
attempts
was
bear
activity
at 0-5 C,
The
(to
mean
0.64 at 5.1-10
C,
Thus, the effect of precipitation and
levels
may
relate
to
both
physical
discomfort and olfactory considerations.
Thermal
temperatures
scents.
factors
and/or
can
also
influence
olfaction.
direct sunlight hasten the evaporation
However, minor
Increased
rate
of
increases in temperature can have a favorable
60
effect
on
olfaction by creating slight updrafts which make
a
scent
more accessible for dispersion under light wind.
The temperature response curves for the annual»
periods
fall)
were bell-shaped with activity peaks at 10-15 C
and
(annual
5-10 C (summer) and lesser activity at temperatures
and below the peak range.
may
summer, and fall
relate
to
Decreased activity at higher
time-of-day effects
(highest
and
above
temperatures
temperatures
occurred
during midday when grizzlies were least likely to be active) and/or to
the
negative
Decreased
activity
adjustment
found
effect
of high temperature
on
olfactory
perception.
at lower temperatures may represent a
to minimize thermal stress.
Garshelis and
similar responses to temperature in summer and
behavioral
Pelton (1980)
fall,
although
their fall data indicated a much broader (20 C range) plateau of
activity
at
intermediate temperatures.
Schleyer (1983) also
maximum activity at intermediate temperatures annually and in
but
the
clear.
relationship
In
of activity to temperature in
spring,
both
Garshelis
and
fall
high
found
summer,
was
less
Pelton (1980)
and
Schleyer (1983) found that activity increased as temperature increased
for most of the temperature range.
to
my
observation
temperatures
ranges
during
and
that
This pattern is in marked contrast
bears were
least
active
at
intermediate
most active in the maximum and minimum
spring.
This result would not seem
to
temperature
follow
from
either physiological or olfactory considerations.
Thermal
microgradients between the ground and the air
affect
scent.
ground
temperature
can
Budgett (1933) found that tracking was best when
exceeded
the air temperature by a
few
also
the
degrees.
61
This
situation
temperatures
higher.
than
occurs
naturally
drop rapidly,
in
the
early
evening
but ground temperatures
as
remain
air
somewhat
The converse is true at dawn when the air warms more rapidly
the ground.
patterns
is
highest
at
Support for olfactory regulation of diel
ambiguous.
Schleyer (1983)
found
that
activity
sunset annually and during spring and fall.
activity at sunset was about equivalent to activity at
activity
In
was
summer,
sunrise.
The
activity peaks of Tennessee black bears occurred between 1600 and 2000
in
all
sunset
three
seasons.
annually
and
in spring and fall,
significant only in fall;
than
at
sunset.
olfaction
are
Grizzlies in my study were most
but
this
active
difference
in summer they were more active at
Hence,
instrumental
it
appears that factors other
in
determining
grizzly
was
sunrise
than
diel
at
just
activity
patterns.
Olfaction
moisture
should be good in fog for
tends to capture scent,
and,
two
2.
for
olfaction.
I.
airborne
fog typically occurs when
cold air moves over warmer moist ground which,
favorable
reasons;
as described above, is
Data from this study were
too
scant
to
evaluate the effects of fog on bear activity; however, Schleyer (1983)
found
that
grizzlies were active well above average when
there
was
fog.
The
winds
effect of wind on olfaction depends on
speed.
Strong
can be less favorable for olfactory searching than light
because
they
scent.
Light winds dilute scent less,
the
its
move
more air past the source and thereby
but take longer to
scent a given distance (Wright 1982).
winds
dilute
the
transport
Thus olfactory perception
62
should
be
best
hypothesis,
strong
coyotes
(40 km/hr)
Wells 1980).
at
in
light
moderate
winds.
Contrary
winds than in light (10 km/hr) winds
significant difference in activity levels when there
high (>50 km/hr) wind.
increased
significant
as
differences
wind speed
in
In my study,
increased,
activity
between
and
no
activity
there
any
there
was
grizzly
but
of
significant
was
generally
and
Schleyer (1983) collected a small amount
of the total variation in grizzly activity levels
versus
in
Perhaps the scent dilution factor only becomes important
portion
wind
this
(Bekoff
data and reported that wind speed did not explain a
no
to
are able to locate prey at greater distances
very long distances.
wind
to
were
two
no
wind
speeds (p=.05).
In summary,
even
most,
conditions.
interaction
number
of
of
The
of
other
olfaction alone does not adequately explain all,
the
variation in grizzly bear
response
to
weather
a
complex
observed responses probably result from
sensory (olfactory and visual) considerations with
factors including
endogenous
rhythms
or
a
(Cloudsley-
Thompson 1961), physiological state, and security.
Energetic Agendas of the Primary Study Bears
The objective of this analysis was twofold:
I.
To
develop
a
conceptual
overview of how
a
given
bear’s
activity patterns, movements, food habits, and habitat use interrelate
and
to
thereby
"agenda."
refer
gain some insight into the
bear’s
broad
The concept of an energetic agenda is introduced
energetic
here
to
to the manner in which a bear tailors its behavior and activity
63
patterns
("Agenda"
to
suit its contemporaneous habitat
and
associated
diet.
implies a coarse fitting of behavior to environment and
preferable
to
the
related concept of energy budget
as
the
is
latter
generally pertains to a more rigorous caloric analysis.)
2.
To
examine
contrasting
patterns
exhibited
by
various
individuals to determine how a "decision” in one arena (say a decision
to
feed primarily on graminoids) might influence the other
variables
(perhaps the overall activity level).
Some
due
of the hypotheses profferred herein are necessarily tenuous
to the small sample size,
highly
subjective
inves" —
approach
but I hope that this first
might
provide some
grist
order
for
and
further
—
Bear 59
Bear
59 remained in the rich mid- to
high-elevation
grass/forb
meadows along Antelope Creek and in the Washburn Range for most of the
monitoring period.
She tended to make short movements within a small
range and returned frequently to particular ridges and meadows.
her
community
site
quality (CSQ) and
relocation
habitat
richness
scans (RHR) indicated that she occupied high-quality habitat in
of
vegetative
representations
structure.
Her
scats
contained
Both
very
terms
high
of graminoids and forbs and her scat value index (SV)
was the highest of the bears sampled.
was also higher than any other bear.
Bear 59's mean activity
level
£o(ACIe)(Afal
,
64
Interpretation:
Mattson
(1984a)
Antelope Creek,
grizzlies
site
has
suggested that in
areas,
such
where feeding opportunity is widespread and
"contagiously"
adjustment
are
certain
microsites).
This
such
as
(Perideridea gairdneri),
default
spatial
of the many food items available in mesic
abundant and well-distributed,
foods,
toward
those foods that characteristically occur
occurs because,
most
specific
in
as
diverse,
may make a "default" adjustment in feeding activity
specific foods (i.e.,
areas,
mesic
biscuitroot
whereas
(Lomatiurn
the
sp.)
site-
and
yampa
are available only in localized areas.
If a
bear
adjusts its behavior so that site-specific foods are accessible,
most
other diet items are likely to be available in adjoining
Bear
59's behavior suggested just such a foraging pattern.
often
She
observed feeding along the fingerlike ridges which ran
the tributaries of Antelope Creek north of Mt. Washburn.
to be selectively feeding in the rocky,
where
sites.
Lomatium
cous
occurred
in
was
between
She appeared
sparsely vegetated microsites
dense
patches
(note
the
high
-I
"contagiousness"
these
the
value,
A
,
in Table 10).
She would comb
sites by digging for tubers and flipping rocks
periphery
travel
to
similar
suitable
a
of the rocky area.
While
habitat,
indiscriminately
Although
Lomatium,
Bear
this
After several passes,
different rocky microsite and
fashion.
commence
reaching
she
feeding
forbs
seemed
would
in
travelling between these patchy islands
she quickened her pace and appeared to be
on
59
until
through
and
to
grasses
orient
her
in
the
feeding
a
of
feeding
interlying
area.
activity
toward
spatial orientation actually resulted from a
default
65
adjustment
to one of the few food sources which was not
available.
Her
relatively
small
per
relocation size indicate that Bear 59
area
satisfy
ubiquitously
short mean daily movements (2.7 km)
was
her short-term energy demands without having to
and
able
travel
to
very
far.
Bear 59’s foraging activities were timed on four occasions . (for
a
total
nous
of 3 1/2 hours of observation time) as she fed
north of Mt.
spent
Washburn.
on
Lomatium
I found that about 65% of her time
was
actually digging for or feeding upon tubers (the two activities
were indistinguishable) while the remainder of the time was devoted to
searching for suitable plants.
In contrast, while travelling between
Lomatium microsites, she fed continuously on grasses and forbs.
extraction
Thus,
of Lomatium tubers appeared to be costly in terms of
both
energy and time as evidenced by 59's very high mean activity level.
The scat analysis indicated that only 13% of Bear 596s digestible
scat
volume
forbs,
consisted
grasses,
and
of Lomatium while 82.6%
sedges.
Thus,
if
visual
consisted
of
other
observations
were
representative of Bear 59*s overall foraging patterns, then she seemed
to be investing substantial time to acquire relatively low volumes
biscuitroot.
relative
of
However, the high digestibility of Lomatium, especially
to
the graminoids (Mealey 1975),
may have resulted
in
an
underestimation of its use through scat analysis alone.
High
energetic
use of Lomatium would not appear to be favored by a
analysis.
only
.27,
that
either
The energetic efficiency value for
one of the five lowest values (Table 10).
Lomatium
It is
visual estimates substantially overestimated
purely
is
apparent
Bear
59's
66
orientation
to Lomatium foraging or else her high activity level
was
related to another as yet unidentified factor.
Bear 38
Synopsis:
Bear 38 remained in the Gneiss Creek/Duck Creek area for most
the
monitoring period.
indicated
Her relocation habitat richness scans
of
(RHR)
median habitat quality and her community site quality index
(CSQ) was the highest of the five bears.
Scat analysis indicated very
high use of grasses and sedges (76% of digestible volume) and her scat
value score was fairly high.
of
moderate
Bear 38's minimum daily movements
were
length but her area per relocation was much larger
than
any other bear.
Her mean activity level was low.
Interpretation:
Theoretically,
CSQ
and RUR should provide two estimates of
same parameter— the quality of a bear's occupied habitat.
However, as
RHR incorporates a broader area (0.5 km radius) encircling the
relocation points,
the two estimates may differ.
the
bear's
Since bear 38's CSQ
I ■
score
was
score
was
utilizing
the
richest microsites within a matrix of otherwise marginal habitat.
Her
moderate,
the
it
highest
would
of
the five bears and
appear that she was
her
selectively
RHR
mean daily movement length of 4.8 km and her large area per relocation
(23.1
km^) suggest that #38's preferred foraging sites were scattered
throughout
her
range and required a moderate
between favorable sites.
understory
cover
of
amount
of
travelling
The community site analyses had a very high
grasses
and
sedges,
and
her
scat
analysis
67
reflected
correspondingly
Frequency=100%).
high
use
of
grand,noids
(Voliime=76%;
Bear 38's relatively low mean activity level of 0.55
likewise reflected the ease with which she was able to satiate herself
once having arrived at these high-density foraging sites.
Bear 50
Synopsis:
Bear
50 remained in the Nez Perce Greek/Firehole River area
most of the monitoring period.
Both her CSQ and RHR values were
(second from lowest in both cases);
between
RHR
for
low
however, there was less disparity
her CSQ value and those of other bears than existed with
value.
Bear
representation
of
50
had
a
high scat
meat in the diet.
value
score
with
her
a
high
Her mean daily movements
were
longer than any other bear, but her area per relocation was relatively
small
indicating considerable travelling within a small
area.
Bear
50's mean activity level was the lowest for the five bears.
Interpretation:
When considered in terms of traditional bear forage plants, #50’s
habitat was certainly depauperate.
period
and
Her home range (for the monitoring
only) was relatively homogenous (recall the low amount of edge
low
habitat diversity values-Table 5) with a
(Table 4).
sparse
understory
I was often baffled by the monotony and apparent lack
of
feeding opportunity at many of Bear 50’s relocation sites.
Although
animal
matter
vegetal feeding opportunity was limited in #50's range,
was plentiful.
The upper Madison River and its
main
tributaries, the Firehole and the Gibbon, are an important elk (Cervus
68
elaphus
nelson!) winter range.
Estimates for the wintering
herd range from 600-850 elk (Craighead et al.
1981).
A
sizable
1972;
Madison
Cole 1972;
Aune
herd of bison (Bison bison) also occupies the
Nez
Perce/Firehole area (Meagher 1973). This area receives substantial use
by grizzlies attracted to carrion and winter-weakened elk and bisonjin
I
the spring and early summer.
A
The high representation
(Volume=48%;
|
of
meat
in
Bear
50's .1981
scats
Frequency=60%) indicated that she was relying heavily on
these ungulates and, to a lesser extent, rodents for sustenance rather
than
was
on vegetation.
efficient
Schleyer (1983) noted that during his study #50
at finding carrion and preyed on elk both
after the elk rutting season.
before
and
He reported that in 1980 she killed two
bull elk and ate a road-killed elk and a bison.
Bear
activity
travel
50's
was
long
pointed
suggest
ungulates:
Perce/Firehole
that
her
i.e.,
and
feeding
she
would
consuming
and grand.noids incidentally during
The presence of elk and human refuse essentially
an otherwise very marginal habitat.
out
that
distances seeking elk or carrion
shrubs (Vaccinium spp.),
her foraging bouts.
subsidized
movements
highly "directed" toward
considerable
garbage,
minimum
subxeric-submesic
areas
Mattson (1984b)
(such
as
the
area) lack a diversity of feeding opportunity and
has
Nez
are
of low value to grizzlies except when associated with ungulate ranges.
Bear
penchant
501s
low mean activity level may also have
for preying on elk.
reflected
her
A predatory bear would be expected
to
adhere to an energetic agenda quite unlike that of a grazing bear.
A
69
bear
which
is adept and efficient at finding and killing
function in spurts of activity.
the
is
periods
and dispatched and the carcass
of
activity
is
activity should be abbreviated.
(lower
would
While searching for vulnerable prey,
activity bouts should be relatively prolonged,
located
elk
but once the prey
being
utilized,
Bear 50's
low
than any other bear) may be an additional
the
diurnal
predatory
adaptation since one would expect ungulates to be least susceptible to
predation during the day.
Bear 15
Synopsis:
Bear
15
spent
most
of
Yellowstone/Hebgen Lake area.
than any other bear.
the
five
meat.
per
the
monitoring
period
in
West
Both his CSQ and RHR scores were lower
Bear 15's scat quality score was the lowest
bears and his scats contained high volumes of
His
the
garbage
mean daily movements were relatively short,
of
and
and his area
relocation was slightly larger than all bears except
#38.
Bear
15's mean activity level was moderate (median).
Interpretation:
Bear 15's behavior is of particular interest for several reasons:
1.
He
was
the only one of the study bears which
appeared
to
be inextricably linked to unnatural (human) food sources.
2.
Additional
data
on
his habits
were
available
from
the
dog-tracking sessions and from previous year's research.
3.
attacked
Bear
and
15
was
positively identified as
the
grizzly
killed a camper at Rainbow Point Campground
on
which
Hebgen
70
Lake in June 1983.
Hence, data pertaining to his prior habits are of
special relevance to Yellowstone
Bear
15’s short-term home range for the monitoring period was in
predominantly
bottoms
PICO/PUTR habitat.
adjoining Hebgen Lake,
Madison
River.
All
these
CSQ and RHR scores indicate.
this
range,
elevation,
#15
He also utilized the
Duck Creek,
areas
opportunity as the associated IV
of
bear management.
offered
affinity
very
Creek,
limited
Despite the intrinsic low
rarely
and
the
feeding
values (Table 12) and Bear 151s poor
ventured
into
mesic areas north of Hebgen Lake.
tenacious
Cougar
willow/sedge
the
productivity
adjoining
higher
Instead, he displayed a
for the lowlands and ricocheted from one spot
to
another, occasionally "camping" in the same locale for several days at
a time.
Examining Bear 151s movement patterns,
that
he
routes
was intimately familiar with the whole of
The
followed by #15 during the dog-rtracking sessions support
this
deliberate
He
seemed to jog from one road or path to another in
fashion;
element
his
impression
range.
impression.
directed
one gains the
there
did not appear to be
to his foraging.
much
random,
non-
His straight-line approach up
residential driveway directly to the dog food bowl and his
a
a
subsequent
route to the "grease pit" on Highway 191 (see p. 16) left little doubt
that he had reconnoitered these circuits previously.
Incidental observations on Bear 15's day beds also suggested that
he was acquainted with particular sites.
It was not unusual to
multiple day beds when following up on radio relocations.
eight day bed sites which were examined for #15,
find
Out of the
all but two had more
71
than
had
one bed for a mean of 14.8 beds per site.
62 day beds,
some appearing to be several years
220 X 30 m area.
a
One relocation
old,
site
within
These multiple bed sites were characteristically in
dense copse of trees (usually lodgepole) which afforded more
than
adjacent
whereabouts
a
areas.
Thus,
it
appeared
that Bear
15
cover
knew
of these exceptional day bed sites and returned
the
to
them
habitually.
It
is
unlikely
that Bear 15 would have been able .to
reach
an
energetic balance in this habitat, had he not subsidized his diet with
human refuse and predation on ungulates.
his
scats
another
and accounted for 46% of the volume.
six
digestible
Garbage appeared in 67%
noted
earlier,
of Bear 15's scats contained such high volumes
trash
familiarity
As
that they were not collected.
with
his
range
enabled
him
to
of
of
non-
Bear 15's
thorough
efficiently
exploit
vulnerable sources of unnatural foods, from dog-food to dumpsters, and
he
was
a perpetual nuisance bear in the Hebgen Lake
pers.
he
comm.).
was
area
(Etzwiler
After monitoring of #15 was discontinued in fall 1982,
trapped
and
relocated twice after incidents
at
a
private
campground and resort.
Much
of
Bear 15's aberrant behavior appeared to be adapted
feeding
on
daytime
and sunset time periods and his high nocturnal activity
well-suited
human-related
foods.
His low activity
level
for
for
for avoiding detection during the times of highest
the
were
human
activity.
His affinity for certain dense copses of trees for day bed
sites
also
was
closely
advantageous for a
associated
with
man.
bear
habitually
using
As noted in the discussion
habitat
on
dog­
72
tracking.
Bear 15's mean consecutive daily movements of 4.1 km may be
a major underestimate of the actual distance travelled,
included
deliberate
as his forays
visits to favored food sources along
a
roughly
circuitous route.
Bear
15
also
(Volume=27%).
used
three
Schleyer
Thus,
were
had a considerable amount of meat
Schleyer
(1983)
his
scats
reported that #15 killed an elk
elk carcasses in spring
1983)
in
1980.
Knight
(pers. comm., in
also observed that #15 killed elk in previous
years.
it appeared that #15 opportunistically preyed on elk when
vulnerable
and
shifted to high use of garbage
and
when
they
elk
were
unavailable.
Bear 76
Synopsis:
Bear
western
76 occupied the rich meadows in the Blacktail
relatively
(median).
#76
and
part of the Washburn Range during the 1982 monitoring period.
Her CSQ and RHR scores were both very high.
were
Plateau
long
and
her
area
per
Her mean daily movements
relocation
She had a high mean activity level.
was
moderate
The scat sample
for
was not adequate to reliably indicate food habits and will not be
discussed herein.
Interpretation:
Bear
seem
76's high activity level and long daily movements
consistent
intuitively
with
expect
the
that
high quality of
in superior habitat
her
range.
where
most
did
One
not
would
energetic
demands could be achieved relatively easily within a small area, bears
I
73
would have abbreviated periods of activity and short daily
The
explanation
movements.
for #76 *s enigmatic activity patterns may relate
to
her age (2 year old) and inexperience.
Bear 76 was trapped along with her mother near Gardiner,
as
a
yearling in September of 1981 and relocated
Plateau.
She
October .
remained
She
then
to
the
Montana
Blackball
with the sow until the latter died
in
mid-
denned alone near the northern Park boundary
and
remained solitary for all of the 1982 field season.
In contrast,
sow
most Yellowstone grizzly cubs (59-64%) den with the
as yearlings and are not weaned until the onset of the
breeding
season
Mitchell 1982;
which
when they are about 2 1/2 years old
Craighead et al.
separate
disadvantage
from
without
1974).
Those bears,
following
(Craighead
such as
the sow as yearlings would seemingly
the
additional year of maternal
and
#76,
be
at
tutelage
a
and
consequently be less efficient at locating and securing desirable food
items.
This
tend
to
weigh
(Craighead
are
observation is supported by the fact that early
less the following year than bears weaned
1972— panel discussion).
weaners
at
2
1/2
Age specific survival rates (P^)
also notably low for two-year old grizzlies regardless of the age
when
weaned
National
(Knight
Academy
weaned
yearlings
tended
to
yearlings
reasonable
be
still
to
and
Eberhardt
of Science 1974).
held
1985;
Craighead
Hornocker (1962)
a low position in the . social
quite timid and apprehensive of
with
assume
following year as well.
their
sow shared
her
that this low status
et al.
reported
bears
social
rank.
be
that
hierarchy
other
would
1974;
and
whereas
It
manifest
is
the
74
There
are
additional ecological considerations which
played a role in #76*s behavior patterns.
among
of
may
have
Baker (1982) suggests that
those animal species in which the adults have a cerebral
sense
location (i.e., a sense of spatial orientation) many of the
young
undergo a period of "exploratory migration."
This phase involves
a
series of movements along unfamiliar routes to unfamiliar destinations
during
which
time the animal assesses the relative suitabilities
the encountered habitat.
with
the
more
Baker contrasts these exploratory migrations
traditional
exploratory migration,
of
concept
of
"dispersal”
which,
includes no systematic appraisal of
unlike
available
habitats.
If
young
following
bears
simply "dispersed"
dissolution
from
parental
of the sow:cub bond and settled in
territories
the
first
available habitat, one would not expect a prolonged period of enhanced
activity accompanied by long movements.
If,
however, young bears do
engage in a phase of vigorous habitat assessment,
be
the
norm.
contribute
Interference
to
high
by
resident
activity levels and
such behavior would
adult
bears
frequent
might
movements
also
(USFWS
1982).
Several
completed
continue
authors
the
have
exploratory
found
that
even
after
phase of its habitat
an
animal
evaluation
it
has
may
to visit suboptimal habitat patches to confirm and/or update
its relative suitability rankings (Krebs and Cowie
1976).
Then,
if
conditions should change, the animal can immediately expand its use of
the
prior
Heinrich
sub-optimal habitats (Smith and Sweatman 1974;
1976).
Baker
(1982) terms this behavior
Oster
and
"revisiting
for
75
reassessment"
(RFR).
Thus,
increased
activity in young bears
may
result from either exploratory migrations, RFR, or both.
Bear
76's
community site analyses indicated high
grasses, sedges, and forbs.
food
but
densities
Were #76 feeding primarily on graminoids,
items with a fairly high energetic efficiency value
which
must
requirements,
however,
grasses
be
of
ingested
in large
volumes
to
(Table
meet
high activity levels would be expected.
10)
nutritive
This did not,
appear to be true for Bear #38 who consumed large volumes of
and
sedges
Regrettably,
the
but
lack
maintained
of
scat
data
a
low
for
mean
Bear
activity
76
level.
precludes
any
substantive conclusions regarding her diet.
In
summary,
then.
Bear 76's activity and movement patterns may
have resulted from any of several factors including inexperience as an
early-weaned
adult
two year old,
bears,
evident
high
low social status and
interference
from
stress factors in the two-year-old age class
in the low survival rate of two year olds),
exploratory
(as
and
RFR movements, and, finally, dietary considerations.
Grizzly Bear Foraging Strategies
One
theories
of
the aims of this study was to gather data to
of optimal foraging to Yellowstone grizzlies.
logistical
constraints inherent in trying to
gather
apply
the
However,
the
contemporaneous
food habit, habitat use, and activity pattern data with a single field
crew were formidable.
Thus, the sample size for several variables was
inadequate to address the questions of optimal foraging.
there
is
a
lack of baseline physiological data specific
In addition,
to
bears.
7b
The
wide disparity in the habitat attributes and diets of
bears,
as apparent in this study,
optimal
foraging
meaningful.
strategy
suggests that a quest for a single
applicable
to
A more productive venture,
individual
individual
all
then,
bears
may
not
be
may be to examine the
strategies pursued by bears in contrasting habitats and to
explore the implications of these distinctions upon bear management.
Although
a
quantitative analysis of
grizzly
optimal
foraging
strategies
was
not attempted,
some qualitative conclusions
may
be
tendered.
The
optimal foraging literature describes three forms
of
optimizations which an animal can pursue (Ellis et al. 1976):
1.
by
Time
minimizers include those animals whose fitness is maximized
minimizing
the amount of time spent feeding to
energy requirement
of
(Schoener 1971).
satisfy
a
given
This strategy is characteristic
animals with a fixed reproductive output and of animals which must
minimize
foraging time to allow time for other
activities,
such
as
mate selection or predator avoidance.
2.
Energy
maximizers
improve their fitness when net energy
for
a
given foraging time is maximized.
Animals whose seasonal reproductive
output
of body
is
a
variable
function
size
or
rate
of
energy
acquisition are likely to be energy maximizers (Schoener 1971).
3.
diet
Nutrient
optimizers
according
to
include those consumers which choose
both energy and nutrient
content
(Emlen
Biochemical composition and phenological stage are important
their
1973).
criteria
for diet item selection (Ellis et al. 1976).
Characteristics
in
Yellowstone
of all three optimization strategies are evident
grizzlies.
Males
may
temporarily
become
time
/
77
minimizers
during
subordinate
courting
to
defending
her
reach
annual
an
expenditure
which
become
time
of
mating as males become preoccupied with locating
and
in
breeding
season.
estrus and,
Feeding
in areas
of
against other males (Hornocker
high
density,
Body
and
weights
high
energy
the breeding season (Craighead and Sumner
1982).
occupy ranges near human habitation may
minimizers as they restrict their
also
foraging
hypothesis,
partially
to
certain
Bear 15's lower than
average
level during the daytime and sunset periods
this
bear
1962).
low due to the low energy intake
the day to avoid detection.
activity
with
are
during
Bears
times
activities
females
the
was
consistent
although his overall mean activity level
was
special cases,
and
slightly above average.
Other
than
these
the concepts
nutrient optimization are more applicable to bears.
studies
based
of
energy
Prior food habit
have concluded that grizzly bear selection of plant food
on
available
grizzly
ecosystems
derived
mainly
Healey 1979).
energy value.
east
from
was
In Yellowstone
Park
and
of the Continental Divide
this
energy
succulent herbaceous vegetation
other
(Healey
1975;
grasses
and
succulent herbs were important in spring and early summer,
and,
from
mid-summer
(Vaccinium
spp.),
In areas west of the Continental Divide,
is
through
fall,
buffaloberries
sugar content of huckleberries
(Shepherdia
canadensis),
(Sorbus spp.) was critical (Martinka 1972;
and
Busby et al.
mountain
ash
1977; Mealey
1979; Sizemore 1980). Starch from underground portions of springbeauty
(Claytonia
spp.),
temporally
important
biscuitroot,
and
other
tuberous
in all ecosystems (Healey 1975;
species
Busby
et
was
al.
78
1977; Schallenberger and Jonkel 1979). Ungulate meat (rich in protein)
and
whitebark pine nuts (rich in carbohydrates and fat) are important
spring and fall foods as available (Mealey 1975,
1979;
Husby et
al.
1977; Kendall 1981).,
Evidence
biochemical
for
diet
selection based on
components (i.e.,
lacking for the grizzly.
a
need
for
particular
nutrient selection or optimization) is
Mattson (pers. comm.) has speculated that in
Yellowstone, the energy available from certain foods such as Equisetum
arvense and Trifolium repens does not appear to adequately account for
the high degree of preference demonstrated for these items.
is
Thus, it
possible that some as yet unidentified biochemical constituent
is
responsible for this selection.
Ellis
et
strategies
but
they
al.
(1976)
described
overlap
point out
that
the
three
optimization
above are not mutually exclusive
to varying degrees
Foraging
bears
depending
on
alternatives,
the
must actually attend
to
consumer's
feeding
niche.
all
three
factors
concurrently such that the energy gain per unit foraging time
is maximized while also achieving an appropiate nutritional balance. A
predatory
bear
may
expend
considerable energy in
the
search
and
pursuit phases of foraging so that the energetic cost!benefit ratio is
critical.
But
composition
of
having
meat
once
subdued
its
is generally suitable
prey,
to
fulfill
nutrient requirements along with its energy demands.
on the other hand,
the
biochemical
the
bear's
A grazing bear,
expends only a moderate amount of energy to pursue
and capture any given item. Biochemical composition, however, may vary
considerably
between
the
many available
species
and
phenological
79
stages, and the herbivorous bear must select, the most beneficial items
for digestibility, nutrient content, and energy.
Optimal
foraging theory distinguishes between the strategic
tactical aspects of diet selection.
the time minimization,
manner
Selection "strategies" pertain to
energy maximization,
options described above.
and
or nutrient maximization
Selection "tactics" refer to the particular
by which a bear endeavors to accomplish
this
strategy.
The
f
food
habits
studies
described
above appear to
support
an
energy
maximization strategy for grizzlies, with protein and/or carbohydrates
being the principal forms of energy
bears
packaging.
However,
individual
in this study differed considerably in the tactics employed
to
accomplish the energy maximization strategy.
The major differences in diet between,
grass/sedge)
number
of
and
of factors.
food
items
for example. Bear 38 (76%
Bear 50 (8.1% grass/sedge) may be attributed
within
a bear’s range and
the
degree
(learned affinities) for particular items are
important.
There are,
has
annual
(Kingsley
the
bears*
of weight gain and loss
et al.
of
acquired
undoubtedly
however, limitations to the latitude which any
in its dietary habits and foraging
cycle
a
The availability and distribution characteristics
preference
bear
to
tactics.
associated
with
The
distinct
hibernation
1983) and the physiological constraints imposed
monogastric digestive system (Bunnell and Hamilton
bracket the dietary variability.
by
1983)
80
Theoretical Considerations of Grizzly Predation on Ungulates
Ungulate meat,
major
primarily in the form of carrion,
food source for Yellowstone grizzlies.
constitutes
a
Mealey (1975) proposed
that competition among grizzlies for elk meat in the spring might have
a regulatory effect on the Yellowstone population.
"walking
dead" peaks in early spring,
Use of carrion and
remains high through
May
and
then becomes relatively low throughout the summer (Mealey 1975; Knight
et al.
1984). Annual variation in use of carrion is governed directly
by availability (Cole 1972;
1982).
1980; Craighead and Sumner
Actual predation on ungulates is greatest in April and May as
grizzlies
prey upon malnourished animals before the herds disperse to
summer ranges.
June
Knight et al.
(Cole
individual
Some bears also prey on newborn calves in late May and
1972).
bears
Craighead
and
Sumner
(1972)
reported
that
apparently recalled the locations of calving
areas
from previous years.
The degree of selectivity shown by vertebrate predators for their
preferred prey (in this case, ungulates) is a function of prey density
(Rolling
1965).
The
selectivity curve (i.e.,
the
exclusivity
feeding on preferred prey) reaches an asymptotic maximum that
on
the ' density
alternative
prey.
of
the preferred prey and on
the
items
(grasses,
relative
to
depends
palatability
Emlen (1966) found that predators may select
profitable prey items over more preferred prey if the less
forbs,
etc.
of
of
less
profitable
in this analysis) become very abundant
the preferred items.
In this
context,
the
increased
vitality and mobility of elk in late spring and summer is analogous to
an effective decrease in the density of preferred prey.
Concurrently,
81
spring
green-up increases the relative abundance and palatability
alternative foods.
studies
Thus,
have recorded,
foraging theory would predict,
and
of
field
a shift from reliance on use of ungulates
to
use of less profitable, but readily available forage species.
Why
then do some bears,
such as Bear 50,
and
continue to prey on elk in summer and fall?
are
involved.
vegetatively,
did
#50's
They
may
occupy
ranges
belie this prediction
A number of
which
although
factors
deficient
include substantial numbers of summering ungulates,
range.
In
these
areas,
the
opportunity
for
as
directed
predation or chance encounter with weakened or diseased animals should
be greater than where prey are more dispersed.
Acquired
skill
is
predacious tendencies.
were
a major factor in
Knight (pers.
determining
a
grizzly's
comm.) felt that certain bears
more adept at killing large mammals than others.
Both #50
and
#15 were inveterate predators which had displayed an enhanced capacity
to kill ungulates in prior years (Schleyer 1983).
One
of
the more interesting patterns to emerge
from
habit/habitat analysis was the apparent fidelity between
deficient habitat,
predation,
had low CSQ and RHR scores.
supplementary
food
and use of garbage.
the
food
vegetatively
Both #15 and #50
They were also the only bears to rely on
items (meat or garbage) to any extent.
In
some
I
respects,
these two food groups constitute very similar food sources.
Both meat and garbage subsidize the available vegetal resources,
contain
a
wide
energetically
food
groups
variety of
rich.
is
both
are
The most obvious distinction between these
two
that meat,
biochemical
if
obtained
components,
via
and
both
predation,
requires
82
considerable energy expenditure to obtain while garbage is essentially
free (disregarding the possible consequences of detection).
a
single
capture
Craighead
and
of
meat
can feed a bear
for
days
However,
(Cole
Sumner 1982) whereas garbage is generally
less
1972;
of
a
prize.
Conclusions based on such a small sample size are tenuous, but it
is
tempting
either
to speculate that #15 and #50 were
psychologically
or
physiologically
energetically dense food items.
somehow
to
a
predisposed
reliance
oh
The low volumes of graminoids in both
bears mid-summer diets imply a "reluctance" to utilize this food group
beyond
what would be expected by low availability alone.
possible
that
It is
increasing the volume of graminoids in the diet
also
might
accelerate the passage rate enough to preclude complete utilization of
any meat present in the digestive tract at the same time.
be
Thus it may
to a bear's energetic advantage to feed exclusively on
meat
when
meat is available (Picton pers. comm.).
Tracking Bears with Trained Bear Dogs
Successful
factors.
The
bear
tracking
freshness
of
using dogs depended on
the
scent
was
a
especially
Tracking was optimal very early in the morning.
number
of
important.
Scent faded
rapidly
as temperatures rose later in the day, and then it was often necessary
to
"work"
particularly
the
dogs until they relocated a
troublesome in xeric habitat,
or rocky areas.
good
scent.
This
was
such as sterile lodgepole
83
Differences
scent
was weak.
between individual dogs were most apparent when
In traditional bear hunts,
the
the hounds run loose in
packs and those with less sensitive olfactory endowments merely follow
the
leader.
Although
experienced,
all
weII-seasoned
eight of the dogs we
bear
dogs,
only
worked
two
or
with
were
three
were
consistently able to follow a trail in marginal conditions.
The
importance of the dogmen cannot be
overemphasized.
Wright
(1982) observed (with reference to police dogs):
...it is the dogmaster-dog combination that operates with
this degree of effectiveness, and the effectiveness depends
as much upon the dogmaster's understanding of the "whats"
and "hows" of smells and smelling as upon the dog's ability
to do the actual sniffing.
Only in this way can the dog's
special capabilities be applied to full advantage and . the
information he receives via his nose be transmitted to his
master.
It
was
cautious
necessary
for
the
dogmen
to
be
especially
whenever the dogs had obvious trouble following
the
trail.
The possibility of intersecting and following the trail of a non-study
bear
was
a serious concern.
Equipping the hounds with
loud
bells
certainly helped, but these bells were audible for a long distance and
their
use
may have led to unnecessary disturbance of the
bears
and
disruption of their normal routine.
Despite these difficulties,
exciting
the use of bear dogs proved to be an
adjunct to traditional research techniques.
The details of
bear behavior revealed by accurately tracing an individual bear's path
were
valuable from both an ethological. and a management
perspective.
Trained
bear dogs can provide much finer resolution in
movement
and
habitat
use studies than is available by other means.
Movement data
84
from
and
telemetry studies are often subject to
researcher
frequently
(torn-up
error.
biased
logs,
these
types
toward
digs,
easily overlooked.
In addition,
the most
topographic
aberrations
followups to radio
conspicuous
fixes
feeding
are
activities
etc.) while grazing and selective foraging are
Tracking with dogs can increase the precision
of studies and show which microhabitats and
which
in
food
items are being exploited.
Bear
program
dogs could be used when an intensive trapping and telemetry
was infeasible.
For example,
when assessing the
impact of a proposed development on a grizzly population,
might
area
need
in
Similarly,
many
to be collared to yield sufficient data specific
question.
substantial
potential
data
bear
Dog
on
dogs
tracking
has
the
localized
areas
might
employed
be
in
potential
relatively
when
the
to
short
bears
to
the
provide
time.
activities
particular bears are of special concern, as in cases of depredation.
of
CONCLUSIONS
The
there
data
imply,
exists
a
characteristics,
within the limits of small sample
substantial
food
habits,
interdependence
and activity
size,
among
patterns.
that
habitat
Contrasting
energetic "agendas" (as overtly manifested in bear behavior
patterns)
are likely to be associated with particular foraging tactics and these
tactical
programs
are
at
least
partially
predictable
given
the
contemporaneous habitat parameters.
A
number
of
outstanding
questions remain to
be
answered
by
further research.
1.
were
Seasonal
shifts in the food habit/activity pattern
not adequately examined herein.
complex
Temporal shifts in food habits
are well documented (Mealey 1975; Knight et al. 1984), as are seasonal
changes
1980).
in
activity patterns (Schleyer 1983;
Additional
research
will
be
Garshelis
required
to
and
Pelton
determine
the
interdependence of these contemporaneous shifts.
2.
To
what
extent
were the observed patterns the
actual preference as opposed to availability?
use
vegetatively
poor
habitat
favorable habitats nearby?
these
this study?
For example;
by default due to
a
lack
did
of
of
#50
more
Or if mid- to high-elevation mesic meadows
with a rich grass/forb flora were available,
utilize
result
would she preferentially
meadows over the lodgepole stands she occupied
during
86
3.
the
What
additional factors might be implicated in
energetic
agenda
provided
herein
observed
behavior
satisfactory.
graminoids
are
of
not the only
and,
For
individual
in
some
example,
bears?
The
plausible
cases,
determining
interpretations
explanations
they
are
for
not
thoroughly
why would Bear 38 have fed primarily on
and forbs and maintained a fairly low mean activity
while
Bear
level
of
59 had a similar diet yet had the highest
any
consequence
bear?
of
Was
the
this an artifact of
mean
the
additional variables not adequately
level
activity
sampling
probed
or
by
a
this
analysis?
4.
and,
To
what
especially,
extent would the differences in activity
food
habits and habitat use,
patterns
even out over
time?
Were the contrasting patterns merely the result of spot-sampling
in
the
long term,
wide trends?
would all bears approach the observed
Conversely,
and,
population
if some bears persistently adhere to
food
habit and activity programs quite unlike the overall trends, this fact
may
have
broad implications for bear management,
particularly
with
regard to habitat preservation.
Grizzly bear habitat evaluations and protective measures designed
to protect areas deemed valuable to the "average" bear may neglect the
welfare
of
certain
habituation,
and
tactics,
have
marginal
habitat.
Yellowstone
decline
individuals
adjustments
contrived
which,
in
through
activity
an energetically
Recent
population
acquired
patterns
viable
projection
and
foraging
lifestyle
models
skills,
within
for
the
grizzlies have suggested a continuing long term (30 year)
with
the
margin
between
this
decline
and
population
87
stabilization
possibly
hinging
on
a
reduction
of
adult
female
mortality by one or two bears per year (Knight and Eberhardt 1984
1985).
Thus,
and
it would seem that management strategies cannot afford
to overlook the well being of any individual bears.
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Schoener, T. W. 1971. Theory of feeding strategies.
Syst. 11:369-404.
Ann. Rev. Ecol.
Sizemore, D . L.
1980.
Foraging strategies of the grizzly bear as
related to its ecological energetics.
M. S . Thesis. Univ. of
Montana, Missoula. 67 pp.
Smith, J. N . M. and H. P. A. Sweatman. 1974. Food searching behavior
of titmice in patchy environments. Ecology 55:1216-1232.
Soil and
Conservation Service.
1983.
Summary of snow
survey
measurements in Colorado, Montana, and South Dakota, 1919-1982.
SCS, Casper, Wyoming.
94
Steele, R., S . V. Cooper, D. M. Ondov, and R. D. Pfister. 1979.
Forest habitat types of eastern Idaho— western Wyoming. USDA
For. Ser.
Intermountain For. and Range Expt. Sta., Ogden, UT.
182 pp.
U . S . Fish & Wildlife Service. 1982. The grizzly bear recovery plan.
Prep, in coop, with MT Dept of Fish, Wildlife and Parks, Don L.
Brown: recovery plan leader.
Coop, agreement no. 14-16-000680-923. 195 ppU . S . Forest Service and National Park Service. 1979. Guidelines for
management involving grizzly bears in the greater Yellowstone
area. 136 pp.
Wright, R. H.
236 pp.
1982.
The sense of smell.
CRC Press, Boca Raton, FL.
95
APPENDICES
96
APPENDIX A
COMMUNITY SITE ANALYSIS FIELD FORM
97
Feed
Site
No.
______________ D a t e
GRIZZLY
BEAR
STUDY
COMMUNITY
SITE
ANALYSIS
______________ O b s e r v e r s
______________________ F o r e s t
U T M ____________________________D r a i n a g e _______________________________________________ B e a r
Flight
D a t e ________________
Aerial
Aspect
_______________________
° S l o p e __________T o p o g r a p h i c
Area
Physiognomy
Habitat
in
between
trees
attach
>
3 m
tall
s i z e _____________________ C o m m u n i t y
TREES
Feed
Subtotal
Cover
Prom.
Total
__________________________________
point
cruise
Ground
cover
No.
Elevation
P o s i t i o n ______________________
measurements)
Photo
No.
______________
_____________________________________
_________________ D i s t a n c e
to
open
or
timber
________
s i z e _________________
cover
>
3 m
tall
Species
Total
SHRUBS
HERBS
timber,
No.
T y p e _____________________________________
A v e . distance
Plot
(if
Photo
___
_______
Feed
Cover
Subtotal
Prom.
cover
<
3 m
cover
Subtotal
forbs
Subtotal
call
Species
grass/sedge
98
Feed
Site
of
Ant
No.
activity:
Vial
No.
50
Scat
Carcass
Track
Gopher
dig
Hair
Gopher
cache
Bed
Root
Claw
g
Sample
No.
Squirrel
Torn
dig
dig
Stripped
Unknown
Turned
Torn
bark
cache
log
rock
anthill
Grazing
dig
Mushrooms
Other
Age
of
Extent
activity:
and
size
of
Detailed
activity
Adjacent
or
Relative
food
feeding
in
community:
associated
source
site:
activities
abundance
not
(.PIAL
in
community:
cones;
b e r r i e s ; root
foods;
c a r c a s s e s ; etc.):
APPENDIX B
TABLES OF HABITAT PARAMETER VALUES AND
COMMUNITY SITE ANALYSIS DATA
100
Table 10. Energetic efficiencies (EE), characteristic contagiousness
(A ), and monthly preference values for the most important
diet items of Yellowstone grizzlies as used in the community
site and scat quality analyses. All values were adapted from
Mattson (in prep.).
Food Item
Ungulates
Rodents
Trout
Pine nuts
Anthills
Graminoids
Lomatium spp.
Perideridia gairdneri
Cirsium spp.
Mushrooms
Potamogeton spp.
Shepherdia canadensis
Claytonia lanceolata
Equisetum arvense
Vaccinium scoparium
Vaccinium globulare
Trifolium repens
Taraxacum spp.
Polygonum spp.
Fragaria spp.
Epilobium spp.
Unid. Forb
EE
A-I
.88
.27
.42
.65
.42
.73
.27
.15
.15
.92
.15
1.00
.96
.46
.81
.92
.46
.46
.69
.73
.85
.40
.99
.82
.91
.99
.41
.82
.99
.99
.74
.50
.99
.91
.99
.91
.74
.91
.82
.66
.66
.74
.58
Preference Values
Apr May Jun Jul Aug Sep Oct
.91 .66 .52 .54
.68 .56 .52 .41
*
.31 .33
.97 .82 .39
.02 .11 .08 .23
.53 .63 .55 .22
.07 .42 .22 .40
.08 .43
.42 .36
.42
.44
.16
.78
.16
.35
.35
.55
.40
.28 .06 .38 .33 .33
.06 .48 .38 .36 .17
.35
.64
.50 .23 .32 .25 .37
.28 .47 .30 .27
.05 .16 .20 .22
.01 .07 .13 .30
.36 .26 .23
Ann
.60 .54
.50 .60
,85
.43
.78 .88
.19 .44
.40 .40
.83
.24
.48
.43
.65
.43
.14
.41
.27
1.00
.38
.34
.62
.29
.37
.24
.16
.23
.68 .55
.40 .35
.48
.25
.33
.13
.23
.33
.23
.38
.32
.06
.32
.11
.34
* Missing values result from 0.0 preference or insufficient sample.
101
Table 11. Monthly Food Values (FV) of the most important
diet
items of Yellowstone grizzlies as used in the community site
analyses. All values adapted from Mattson (in prep.).
Food Item
Ungulates
Rodents
Trout
Pine nuts
Anthills
Graminoids
-'Lomatium spp.
Perideridia gairdneri
Cirsium spp.
Mushrooms
Potamogeton spp.
-Shepherdia canadensis
Claytonia lanceolata
Equisetum arvense
Vaccinium scoparium
Vaccinium globulare
Trifolium repens
Taraxacum spp.
'Polygonum spp.
Fragaria spp.
Epilobium spp.
Apr
May
1 Jun
Jul
Aug
Sep
Oct
Ann
.79
.15
*
.57
.12
.45
.11
.12
.53
.01
.33
.06
.01
.05
.47
.09
.06
.25
.04
.27
.11
.06
.04
•37
.03
.52
.11
.47
.13
.74
.09
.50
.03
.21
.09
.08
.04
.50
.03
.24
.57
.08
.24
.10
.04
.08
.04
.36
.16
.31
.15
.53
.04
.29
.11
,10
.05
.06
.06
.25
.95
.16
.20
.53
.11
.11
.11
.09
.11
.00
.32
.02
.27
.02
.19
.62
.02
.38
.11
.06
.20
.09
.08
.02
.00
.12
.14
.07
.04
.18
.09
.09
.09
.07
.13
.31 .
.15
.21
.54
.14
.08
.10
.16
.11
.20
.15
.28
.05
.07
.15
.12
.19
.19
.05
.12
.06
.17
* Missing values result from 0.0 preference or inadequate sample.
102
Table 12. Unit area importance values
types for habitat richness
types which occurred in the
five primary study bears are
(IVU's) used to score habitat
analysis. Only those habitat
computer habitat scans for the
included.
Forest Habitat Types:
ABLA/VASC-VASC1
ABLA/VASC-CARU
ABLA/VASC-PIAL
ABLA/CACA^
PIEN/EQAR2
ABLA/THOC
ABLA/CAGE
ABLA/LIBO-VASC
ABLA/VAGL-VAGL
ABLA/CARU
PICO/CARO
PICO/PUTR
PSME/SYAL
PSME/CARU
P!AL/VASC
Spring
Summer
Fall
.003
.018
.000
.106
.514
.004
.009
.014
.000
.000
.000
.009
.001
.003
.000
.152
.084
.467
.213
.253
.033,
.010
.139
.257
.012
.000
.038
.002
.016
.229
.307
•909
.964
.660
.000
.125
.018
.000
.000
.000
.000
.003
.000
.018
.343
.000
.688
.072
.000
.036
.358
.495
.178
.356
.172
.133
.688
.000
.273
.084
.251
.208
.162
.124
.167
.201
.100
.195
.017
.062
.608
.089
.082
.000
.492
.246
.000
.026
.000
.444
.000
.200
.155
.000
.529
.000
.262
Non-forest Habitat Types:
FEID/AGSP
FEID/AGCA
FEID/AGCA-GEVI
FEID/DECE
DECE/Carex spp.
ARTR/FEID
ARTR/FEID-GEVI
3
Dry Artemisia spp. shrubland
_
Moist Artemisia spp./Potentilla shrublandJ
Sedge bogs,marsh fens,wet areas
Alpine tundra (high elev. rocky grassland)
ScirpuS spp./Carex spp. (hot spring veg.)
Salix spp./Carex spp. (at high elev.)
Salix spp./Carex spp. (at low elev.)
1 When names of three species are included in the
the third species gives the habitat type phase.
habitat type name,
2 Corresponds
to Despain1s (1984) "Wet Forest" habitat
types:
ABLA/CACA for high elevations and PIEN/EQAR for low
elevations.
3 These types
were mapped in the Gallatin National
represent groupings of several habitat types.
Forest
and
103
Table 13. Community site scores for Food Value (FV), Understory Cover
(Cu ), Understory Species Diversity (H ), and Community Site
Quality (CSQ). See text for description of variables.
Proportional values are given in parentheses.
Site #
Use Date
FV
C
H
U
CSQ
U
4204
4209
4210
4215
4216
4220
4221
4222
4/29
5/13
5/21
5/28
6/15
7/26
7/27
7/15
1.38 (.70)
0.84 (.43)
1.58 (.80) .
1.29 (.65)
1.58 (.80)
0.80 (.41)
1.17 (.59)
1.97(1.00)
3 (.37)
3 (.37)
4 (.50)
8(1.00)
7 (.87)
6 (.75)
7 (.87)
7 (.87)
2.04 (.55)
2.67 (.72)
2.51 (.68)
2.72 (.74)
2.37 (.64)
2.24 (.61)
3.68(1.00)
0.66 (.18)
2.32
1.95
2.78
3.04
3.11
2.18
3.05
3.05
4206
4211
4212
U
cd
<D 4213
PP
4214
5/4
5/31
6/1
5/28
6/3
0.44
1.41
0.72
0.78
0.72
(.22)
(.72)
(.36)
(.40)
(.36)
4
4
5
4
3
(.50)
(.50)
(.62)
(.50)
(.37)
0.51
3.04
3.05
2.54
2.47
(.14)
(.83)
(.83)
(.69)
(.67)
1.08
2.77
2.17
1.99
1.76
UO
4238
W 4239
cd 4240
0)
pq 4241
8/25
8/26
8/26
9/10
0.40
0.60
1.82
0.21
(.20)
(.30)
(.92)
(.10)
4 (.50)
3 (.37)
8(1.00)
2 (.25)
2.71
3.18
1.06
2.89
(.74)
(.86)
(.29)
(.78)
1.64
1.83
3.13
1.23
4231
4232
4234
4235
4236
7/17
7/29
8/5
8/16
8/17
1.69
1.51
0.83
0.69
1.12
(.86)
(.77)
(.42)
(.35)
(.57)
6
6
5
2
2
3.43
1.72
3.33
1.79
2.30
(.93)
(.47)
(.90)
(.49)
(.62)
3.40
2.76
2.36
1.44
2.01
r>. 4229
M 4230
QJ
4233
PP
6/30
7/6
8/12
1.70 (.86)
1.56 (.79)
0.80 (.41)
3.26 (.89)
1.70 (.46)
2.31 (.63)
3.23
2.92
1.82
CO
CO
U
cd
(U
PO
O
LA
Os
m
M
QJ
(.75)
(.75)
(.62)
(.25)
(.25)
5 (.62)
7 (.87)
3 (.37)
X
MONTANA STATE UNIVERSITY LIBRARIES
762 1001 4204 9
MAIN
N378
H25U
cop. 2