AN ABSTRACT OF TEE TEES IS OF
Mark Steven Hinschberger for the degree of Master of Science
in Fisheries and Wildlife
esented on
May Li, 1978
Title: OCCURRENCE AND RELATIVE ABUNDANCE OF SMALL MAMMALS ASSOCIATED
$ ALONG TEE COLUMBIA RIVER
Redacted for Privacy
Abstract approved:
Dr. E. C}
les Meslow
A small mamma]. inventory of occurrence and relative abundance was
conducted in riparian and upland habitats in six segments along the
lower Columbia River from the river mouth to. MeNary Dam (river mile
292) during 19714. and 1975 by removal trapping on standardized
trap lines.
Analysis of variance was used to compare capture per 100 trap-night
indices of abundance of a species or group of species among habitats
within a segment and among segments ci' the study area.
Of the 59 species of small mannials purported to occur near the
Columbia River, 39
were encountered.
Many of
the
species not encounter-
ed. occur at elevations higher than the study area or are rare.
Although
23 species were captured in standardized. traps, the deer mouse (Peromyscus maniculatus) and vagrant shrew (Sorex va'ans.) comprised 814..9 per-
cent of the.total catch.
The deer nouse, the most abundant species, occurred in all 38 hab-
itats except Russian olive (Elaeagnus antifolia) and increased in
abundance from west to east.
Insectivores, mainly vagrant srews, were most abundant in the west
and. decreased in abundance along the decreasing moisture
west to east as did voles (Microtus spp.).
adient from
Occ.z'rence and Relative Abundance of Small Manin-ials
Associated with Ri.r±an and Upland Habitats Along
The Columbia River
Mark Steven Hinschberger
A THESIS
submitted to
Oregon State University
in
rtial fulfill-rient. of
the reauirements for the
degree of
Master of Science
Commencement June 1978
APPROVED:
Redacted for Privacy
Associafe Professor 6f'Fjtsheries and Wildlife
in charge of major
Redacted for Privacy
Head of Department of Fisheries and Wildlife
Redacted for Privacy
Dean of Graduate School
Date thesis is presented
May Lij,
1978
Typed by Mark Steven Hinschberger for Mark Steven Hinschberger
TABLE OF CONTTS
Page
I.
II.
III.
Iv.
INTRODUCTION
1
STUDY AREA
Climate
Description of Segments
Intensive Sampling Areas
3
3
3
10
NETHODS
Sampling
Index of Abundance
Analysis
12
12
14
17
RULTS AND DISCUSSION
18
Segment
Segment
Segment
Segment
Segment
Segment
1
2
3
4
5
6
Geoaphic Distribution
V.
VI.
18
22
26
29
33
33
39
LITERATURE CIT
46
APPENDIC
51
LIST OF TA3L
Table
1.
2.
3.
4.
5.
6.
Page
Small mammals occurring along the Columbia River. Study
area segments listed after species represent range according to various authors. Underscoring denotes occurrence
during this study.
19
Total number of individuals of each mammalian species
captured in standardized gmound traps in intensive sampling
areas of the Columbia River study area in fall 1974 and
spring 1975.
20
Mean index of abundance (captures per 100 trap-nights)
values of small mammals in habitats inventoried in segment
1 of the Columbia River study area.
21
Mean index of abundance (captures per 100 trap-nights)
values of small mammals in habitats inventoried in segment
2of the Columbia River study area.
23
Mean index of abundance (captures per 100 trap-nights)
values of small mammals in habitats inventoried in segment
3 of the Columbia River study area.
27
Mean index of abundance (captures per 100 trap-nights)
values of small mammals in habitats inventoried in segment
4 of the Columbia River study area.
30
7.
Mean index of abundance (captures per 100 trap-nights)
values of small mammals in habitats inventoried in segment
5 of the Columbia River study area.
8.
Mean index of abundance (captures per 100 trap-nights)
values of small mammals in habitats inventoried in segment
6 of the Columbia River study area.
35
Mean index of abundance (captures per 100 trap-nights)
values of small mammals in segments of the Columbia River
study area during 1974, 1975.
41
9.
Appendix Tables
A
B
C
D
E
F
G
H
I
J
K
Page
Intensive sampling areas established in the Columbia
River study area, 1974-1975.
51
Mean index of abundance values (captures per 100 trapnights) in small mammal intensive sampling areas inventoried. during fall 1974 and spring 19'75 in segment 1 o±
the Columbia River study area.
57
Small mammal captures per 100 trap-nights and species
diversity index values by trap station type in habitats
inventoried in segment I of the Columbia River study area.
58
Mean index of abundance values (captures per 100 trapnights) in small mammal intensive sampling areas inventoried during fall 197L1. and, spring 1975 in segment 2 of
the Columbia River study area.
59
Small mammal captures per 100 trap-nights and species
diversity index values by trap station type in habitats
inventoried. in segment 2 of the Columbia River study area.
61
Mean index of abundance values (captures per 100 trapnights) in small mammal intensive sampling areas inventoried during fall 1974 and spring 1975 in segment 3 of
the Columbia River study area.
63
Small mammal captures per 100 trap-nights and species
diversity index values by trap station type in habitats
inventoried in segment 3 of the Columbia River study area.
65
Mean index of abundance values (captures per 100 trapnights) in small mammal intensive sampling areas inventoned d.uning fall 1974 and spring 1975 in segment 4 of
the Columbia River study area.
67
Small mammal captures per 100 trap-nights and species
diversity index values by trap station type in habitats
inventoried in segment 4 of the Columbia River study area.
69
Mean index of abundance values (captures per 100 trapnights) in small mammal intensive sampling areas inventoried during fall 1974 and spring 1975 in segment 5 of
the Columbia River study area.
71
Small mammal captures per 100 trap-nights and. species
diversity index values by trap station type in habitats
inventoried in segment 5 of the Columbia River study area.
72
Appendix Table
L
M
Page
Mean index of abundance values (captures per 100 trapnights) in small mammal intensive sampling areas inventoried during fall 197/+ and spring 1975 in segment 6 of
the Columbia River study area.
7/4
Small mammal captures per 100 trap-nights and. species
diversity index values by trap station type in habitats
inventoried in segment 6 of the Columbia River study area.
76
LIST OF FIGUR
Figure
Page
1.
Segments of the Columbia River study area, 1974-1975.
2.
Small mammal trap placement at trap stations 1-16 located
at 33-rn intervals along a 500-rn transect in intensive sampling areas of the Columbia River study area, 1974-1975.
4
15
OCCURRTCE AND RTIVE ABUNDANCE OF SMALL MA?ALS
ASSOCIAT
WITH RARIAN AND UPLAND HABITATS ALONG
THE COLLTh2IA RIVER
1TRODUCTION
Flooding of riparian habitat to create the existing hydroelectric
generating plants on the Columbia and. Snake Rivers drastically reduced
riparian wildlife habitat (Eicher 1968, Gibson and. Buss 1972, Lewke and
Buss 1.977).
Currently the principal
Northwest is hydroelectric.
ower supply system of the Pacific
Plans for the future power supply incorpo-
rate a thermal system for base power needs and. employ existing hydroelec-
tric plants for peak power demands.
Use of hydroelectric plants for
power peaking demands will increase the frequency and severity of water
fluctuations.
This modification further threatens wildlife resources
associated with the remaining r±parlan habitat of the Columbia and Snake
Rivers (Johnsgard. 195, Stanford. Research Institute 1971, Clarie et al.
1971).
The. Wildlife Work Group, established by the U.S. Army Corns of
Engineers to coordinate wildlife research as it relates to water regulation of the Columbia and. Snake Rivers, determined that an inventory of
riparian hab1.tats and associated wildlife populations was the first
research priority.
The area of interest was the Columbia River from its
mouth to the Canadian border and. the Snake River unstream to and, includ-
ing Brownlee Reservoir.
The portion of the study on the Columbia River from its niouth to
McNaxy Dam was conducted by the Cooperative Wildlife Research Unit at
Oregon State University (Tabor 1976).
ALthough the base study involved
2
all wild. vertebrates excluding fish, only Information on small mammals
is presented in this paper.
Numerous sources of information on ma.mmalian occurrence and. distri-
bution in Oregon and WashIngton axe available (Bailey 1936, DaJ4uist
19L.8, Hall and Kelson 1959, Burt and. Grossenheider 1964., Ingles 1965,
Gordon 1966, Lauckhart 1970, Larrison 1970, Maser and Storm 1970, 1lerts
1971, Olterman and. 1lerts 1972).
Field. collections by the Bureau of Biol-
ogical Survey (Bailey 1936) supplied most of the intial information on
occurrence and distribution of niaminals in Oregon and, along the Columbia
River.
Current information that is available concerning mammalian fauna
along the Columbia River, however, is limited and general, and restricted
primarily to economically important game species and furbearers (Ives
and Saltzman 1970, Stanford. Research Institute 1971, Suring 1975).
Small
mammals and other non-game species have received little attention (Gordon
1966, Stanford Research nstitute 1971, Battelle, Pacific Northwest
Laboratories 197k', Hedluzid. and. Rickard. 1976).
The present study was initiated with the following objectives:
(1) to examine small mammal occurrence and. distribution in riparian and
upland habitats of the lower Columbia River;
the abundance of certain species and
(2) to determine whether
oups of species varied among
habitats within a senent of the study aa; and (3) to determine
whether the abundance of certain species and.
among segiients of the study area.
oups of species varied
3
STTJDY AREA
Climate
The study area extended from. the seaward end of the Columbia River
jetties to McNary Dam, a distance of approximately 292 river miles.
Climate of the study area, discussed by Franklin and Dness
Lynott
(1966),
and Rudd
(1962),
(1973),
changes from maritime in western Oregon
and. Washington (characterized, by heavy precIpitation and. mild tempera-
tures) to a continental climate east of the Cascade Mountain Range
(characterized by low precipitation and more extreme temperatures).
Annual precipitation in the study area ranges from 180 to 250 cm at
Astoria, Oregon (RN giver
(RI 289).
mil7'13)
to 10 to 20 cm at Umatila, Oregon
January mean minimum and. July mean maximum temperatures
range from 0.0°C and 20.0°C, respectively, at Astoria to -5.0°C and
33.5
0
C, respectively, at Ijmatilla (Franklin and Dyrness
1973).
The
Columbia Gorge is- the area of transition from marine to continental
climate.
Weather disturbances there occur frequently, particularly
during the winter when marine low-pressure systems moving westerly
collide with cold. continental air.
Description of Seients
The
study
area was divided into the following six seients (Fig. 1);
(t) RN 0 to RN 12 (mouth of Youngs River);
79 to Bonneville
(3)
RN
(5)
The Da1J.es Pool (RN
292).
Dam (RN tL.5);
192-215.6);
(L.)
and
(2) RN 12 to RN
79;
Bonneville Pool (RN 1LI.5_192);
(6)
John Day Pool (RN
215.6-
(J
Figure 1.
Segments of the Columbia River study area, 1974-1975.
Plant
romenclature follows that of Hitchcock and. Cronquist (197).
Segment 1--Wet beach and stabilized foredunes characterized the
mouth of the Columbia River.
Vegetated foredunes were dominated by
beachgmass (Ammophila arenaria).
Tidal marshes and mudflats occurred
on the immediate river shoreline near the mouth and were submerged daily
by incoming ocean tides. Sitka spruce (Picea sitchensis) was common in
the intertidal zone and near the river mouth, but red aider (Alnus
rubra) dominated most recently disturbed and poorly drained bog sites
in intertidal areas.
Segment 2--Riparian vegetative communities of Sitka spruce, black
cottonwood (Populus trichocarpa), and dense, tail shrubs such as creek
dogwood (Cornus stolonifera) and several willow species
(Salix
spp.)
were characteristic of shorelines and borders of tidal flats and channels
in the western portion of segment 2. Islands in segment 2 closer to the
mouth of the Columbia River were subject to major tidal influences and
were mainly marshy tidelands. Islar4s farther rpriver were characterized. by tall, dense shrub communities with scattered. Sitka spruce,
red aider, and black cottonwood. The coastal climatic influence, appar-
ent in segment 1 and. indicated by the presence of Sitka spruce, emctended
eastward, in segment 2 to Cathlaniet Washington (p L.O41).
Above that
point in this segment, river island and shoreline coinn'iunities were more
tyDically riparian forests of black cottonwood and willow species
(Franklin and, Dyrness 197j).
Segment 3--In this segment most of the river shoreline and islands
were characterized by sandy beaches bordered by long, narrow stands of
black cottonwood/Pacific willow (Salix lasiandza).
Black cottonwood was
the dominant tree species, although Pacific willow often dominated lower
areas exposed to high water.
Oregon ash (Fraxinus lati±'olia) had a
scattered distribution arid usually remained under the main forest canopy.
Near Sauvies Island (RM 87-101) Oregon ash increased, in density, d.cini-
rating scattered sites.
(Rubu
Typically, creek dogwood, Pacific blackberry
ursinus), Himalayan blackberry (R. discolor), and. snowberry
(Symphoricarpos albus) were understory shrubs, but yielded to extremely
dense stinging nettle (Urtica dioica) and reed canary'ass (Phalaris
arundinacea) stands.
Stinging nettle was the dominant f orb under a
black cottonwood canopy.
Reed canary'ass dominated open areas and was
a codominant species in bl.ck cottonwood/Pacific willow ecotones.
Columbia River willow (Salix fluviatilas) and. Pacific willow formed
dense star4s on sites subject to frequent flooding.
Senent L_A niesic to xeric vegetation
to east in seaent 14.
adient occurred from west
The valley floor and lower slopes of the steep
gorge in the west end of this seent were occupied by mesic coniferous
forests, largely Douglas fir (Pseudotsuga menziesii) and western hemlock
(Tsuga heterohylla) with scattered bigleai maple (Acer macroohyllum).
Snowberry, vine maple (A. circinatum), poison oak (Rhus dversioba),
salal (Oaultheria shallo n), and Orego n'ape (B er'oeris spp.) were
dominant understory shrubs.
Eastward,
onderosa pine (Pinus
ad.ua1ly replaced Douglas fir/western hemlock communities.
onderosa)
Oregon
white oak (Q.uercus garryana) was dominant on xeric sites and, formed an
association with pondarosa pine on slopes near the river.
Snowberry,
vine maple, poison oak, bitter1rush (P'sia triden±ata), and. tall
7
Oregonape (Berberis aquilfoliuni) were major shrub species in ponderosa
pine/oregon white oak communities.
Idaho fescue (Festuca id.ahoensis),
bluebunch wheat'ass (Aopyron spicatuin), and, cheatass (Bromus
tectoruin). were dominant
ass species.
Poison oak formed extremely dense stands ur4er Oregon white oak
canopies.
Snowberry, creambush ocean-spray (Holodiscus discolor), and
dull Oregonape (Berberis nervosa) added to the shrub diversity.
In the eastern end of senent
L.
forest vegetation was replaced by
semi-arid, steppe vegetation. Cliffs with steep talus slopes formed the
gorge walls in much of this area. Grasses, predominantly cheatass
and.
Sandberg's blueass (Poa sandbergii), covered slopes having a soil
layer. Shrubs were found on slopes below cliff faces, talus, and narrow,
steep-walled creek bottoms. Maples (Acer spp.) dominated the creek
bottoms;
ceanothus (Ceanothus spp.) and bitter cherry (Prunus emargi-
na-ta), the talus; and. bitterbrush arid rabbitbrush (Chrysothamnus spp.),
the slopes.
Pacific willow, Columbia River willow, and. peach-leaf willow (Salix
amygdaloides) formed dense stands on low, moist sites near the river.
Reed canaryass dominated the ur4erstory. Subject to frequent flooding,
some sites accumulated large amounts of driftwood and. had sparse herba-
ceous understories consisting primarily of sedges (Carex
sDp.).
In addition to riparian vegetation, rock rip-raD, a land form class,
bordered. 3L. percent of the total miles of shoreline in segment
Lk.
Rock
rip-rap, used, as foundation for railroad gmades and, highways and to ore-
vent shoreline erosion, was nearly void of vegetation.
Segment 5--Vertical rock cliffs with narrow plateaus above and,
a
steep talus slopes and. gentle or steep sloping
much of the gorge walls in. segment 5.
asslands below foned
Gray rabbitbrush (Chrsothaus
nauseosus) was the dominant overstory species on the plateaus, but
bitterbrush, big sagebrush (Artemisia trid.entata), and. ceanothus occurred, sparingly.
Dominant gasses covering the steep slopes beneath the
cliffs and occurring as an understory to the shrubs on the plateaus were
cheatass and. Sand.'ce.rg' s blueass.
Other
asses present were Idaho
fescue, bluebunch wheatass, bulbous blue'ass (Poa bulbosa), and. sixweek fescue (Festuca bromoides).
Gray rabbitbrush with a cheatgmass
understory covered most of the gentle slopes beneath the rock cliffs.
Some portions of this segment on the Washington shore were gentle
sloping
asslands with few cliffs and talus slopes.
common in these areas.
Shrubs were not
Gray rabbitbrush, bitterbrush, and buckwheat
(&'iogonuxn spp.) occurred, on a few locations around talus.
Balsamroot
(Balsainorhiza sp.) and lupines (Luinus spp.) were common on the
'assy
slopes dominated by cheatgmass, Sandberg' s bluegmass, and bluebunch
wheatass.
Peach-leaf willow, slender willow (Salix exigua), ar4 Columbia
River willow were the primary overstory species occurring in small
patches along the river shore and eiubayments of this segment.
Pacific
willow, black cottonwood, and. Great Plains cottonwocd (Populus deltoides)
occurred less frequently.
Herbeceous vegetation was "patchy" with reed
canaryass, licorice-root (O-lychiza leoidota), horseweed (Conyza
cans1ensis), western valerian (Valeriana occidentalis), and narrow-leaved
milkweed (Asciepias fascicularis) occurring in. the understories.
As in. segment Li., much o± the river (L.o percent of the total miles
of shoreline) was bordered. by rock rip-rap.
Vegetative cover is very
sparse to non-existent in this habitat.
Seient 6--Steep talus slopes below vertical cliff faces formed
most of the gorge walls in the western part of segment 6.
Hackberry
(Celtis reticulata), ceanothus, common chokecherry (Prunus virginiana),
and juniper (Juniperus sp.) occurred sparingly in the talus.
of the steep slopes not covered with talus were gm'asslar4.
common
Portions
The most
'assez were Sand,berg' s bluegrass, cheat grass, arid bluebunch
wheat grass .
Gray and green rabbitbrush (Chrysothaninus viscidiflorus),
buckwheat, and. a small amount of big sagebrush occurred, on the lower
portions of these slopes.
Big sagebrush occurred in the bottoms of
moist side canyons and draws.
Most of the immediate shoreline in this
area was vertical rock cliffs or rock rip-rap.
Eastward, the topography changed from river gorge to gently rising
slopes.
Green rabbitbrush dominated the shrub layer of vegetation on
slopes well above the river level.
Gray rabbitbrush with a cheatgrass
understory covered the lower slopes of most of the area.
In scattered
locations bitterbrush, big sagebrush, and. green. rabbitbrush were codomi-
nants with gray rabbitbrush.
Other grasses in the area were Sandberg' s
bluegrass, western need.legrass (pa occidentalis), and bluebunch
wheatgrass.
The immediate shoreline of the river
in
much of this area
was vertical rock cliffs.
TopograDhy in. the eastern portion of segment 6 beyond the rivers
edge varied from gently rising slopes to aliost flat.
The area was
mostly grass and shrublarid with irrigated farmland, ponds, and. ina.rshes
interspersed, from approximately iM 270 eastward.
Gray and, green rabbit-
10
brush were the major shrub species, and big sagebrush and bitterbrush
dominated the sandy areas.
Cheatgrass and Sandberg s bluegrass were the
major grasses.
Much of the river shoreline was sand and rock rip-rap in this eastem
portion of seaent 6.
Great Plains cottonwood, peach-leaf willow,
Russian olive (Elaeagnus anustifolia),. and. locust (Robinia sp.), how-
ever, occuied in patches along the river shore and many of the ponds,
marshes, and. sJ.oughs.
Most por4s and, marshes in ths area supported
lush growths of marsh vegetation dominated by common cat-tail (Typha
latifolia), bulrushes (Scirpus spp.), rushes (Juncus spp.), sed.ges,
sweet-clovers (Nelilotüs spp.), and. water smar-tweed (Polygonum coccineun).
Intensive Sampling Areas
cisting broad. vegetative types (based on vegetative overstory)
and land form classes (those areas without vegetation) within the study
area bound.aries were identified and delineated from aerial photographs.
Identification and delineation on. photographs were verified by field
observations made from air and ground checks.
Acreage estimates made
from the photographs with a dot grid were used to determine the major
vegetative types and. land. form classes (habitats) within each seaent
(Tabor 1976:2+1-5).
habitats located near the river shoreline (ripaxiazi habitats) were
considered to be of greater importance in this study than habitats at
higher elevation within the study area.
Intensive sampling areas were
established. in ripaxian habitats and in each major vegetative type and
land form class identified in each senent of the study area.
Intensive
11
sampling areas were not established, on ir4ustrial, residential, or cu.ltivated lands.
An intensive sampling area was established on both the Oregon and
Washinon shores in each of the major types of habitat that occed
in each seiient.
In senents 2 and 3 an intensive sampling area was
established in each major habitat on an island.
Intensive sampling areas
were located in "homogeneous" stands of the habitat and,, where feasible,
wefl inside the boundaries of the habitat to avoid "edge effect."
Tabor (197684-268) presented the exact location, physical characteristics, and, vegetative community of each of these intensive sampling areas.
12
.THODS
Sampling
In small mammal studies two fundamentally different types of trapping have been used to estimate population densities.
In one, animals
are marked and. released into the population from which they were captured.
In the other, animals are removed as captured.
Mark-ar4-release trapping makes possible the study of many phases
of life history (Hayne 1949, Blair 1940a-c) and leaves fauna in nearly
the same conditions for further studies (Dice 1931,1941).
For exten-
sive studies, however, this method is too laborious and, time consuming
and is not practical for sampling a large number of habitats in a short
period of time (Stickel 1948).
The primary objectives of this study were to determine occurrence
and relative abundance (not population densities) of small mammals in
numerous habitats.
A simple field method, with equalized intensity in
all sampling areas, was needed, therefore, to inventory a variety of
small mammals in a short -time.
Mark-and-release trapping with a single
trap type and removal trapping with a
id or quadrat arrangement to
estimate population densities (Stickej. 1946, Hayne 1949, Zippin 1956,
1953) were impractical.
Relative, index figures for a species (rather than density estimates),
calculated from captures along trap lines of measured lengths and. main-
tained for a standard number of days, are comparable for different
habitats, seasons, or areas (Dice 1931, 1938,1941, Southern 1965,
Hansson 1967).
The assumption that alJ. individuals of a species or
13
species
oup have the same probability of capture in all habitats and
areas (segments) during all sampling periods is inherent in comparing
the relative abundance of a species or species
ou
among habitats and
segments.
Removal trapping with a variety of traps in a standardized sequence
along a line transect was used to inventory small mammal populations in
intensive sampling areas during two sampling periods.
The fail 197L
sampling period began 17 August in segment 1 and was completed 30
ber in segment 6.
overn-
All 82 intensive samling areas were inventoried with
at least two consecutive trap-nights during the fall inventory.
spring period was 3 May-15 July 1975.
The
Order of sampling was segment 3
(some sampling areas), L. (some sampling areas), 5,
sampling areas), and Li. (some sampling areas).
6,
1, 2, 3, (some
An attempt was made to
inventory areas of low elevation before spring high water flooded them;
those areas sampled first in segments 3 and. Li. were such areas.
Fifty-
four sampling areas were inventoried during the spring sampling period
with at least three consecutive trap-nights.
Only capture data gathered
during the first two consecutive trap-nights were used for relative
abundance comparisons among habitats within a segment.
This protocol
was a4opted because data collected during both sampling periods in inten-
sive sampling areas of similar habitat within a segment were combined.
Trap stations were established at 33-m intervals along a linear
transect within each intensive samltng area.
The length of a transect
varied according to the size of the intensive sampling area;
station, 500-m transect was the maximum length.
but a 13
One baited and one
unbaited Museum Special snap trap were set at each trap station.
In
1L
addition, baited Victor rat traps, baited Sherman live traps, and
baited pitfall traps on the
Un-
ound and baited Museum Special snap traps
and baited Sherman live traps in trees were used in a standaxdized
sequence as shown in Figure 2. These standardized traps were located
within a 5rn. radius of each station. Additional traps such as No. 110
and 220 Conibear traps, Cinch and Victor gopher traps, and. 0u-O'Sight
mole traps were used where sign and. appropriate conditions occurred;
thus these traps were not included in the standardized sequence.
To attract a gneater diversity of mammals and still simplify the
procedure for baiting traps, a bait mixture consisting of beef suet,
peanut butter,
gmc
und raisins, oatmeal, and. parafn wax was used (Tab er
and Cowan 1971).
Captures in all trap types during all trap-nights, visual sightings,
tracks, scat, and. other sign recorded in each habitat were used to document the occurrence of species. Small mammal species identified in
this study are referred to primarily by common name throughout this
paper. Scientific and common names presented in Table 1 follow Jones
et aJ.. (1975).
Index of Abundance
An index of abundance (bA) value for each captured species and
oup of species (e.g., voles, mice, insectivores, total mammals) by
trap station type, intensive sampling area, habitat, and segment of the
study area was expressed as captures per 100 tra-nights. Only captures
in standardized gnound traps were used in calculating these bA values.
Capture data from intensive sampling areas of similar habitat and both
sampling periods were combined to determine bOA values by habitat and.
2
3
5
16
'I,
.. 0.
1°
VI.
1
o
V
Li
®
4'
Figure 2.
Museum Special baited
Museum Special, unbalted
Victor Rat, balled
Sherman, bailed
Pitfall, unbolted
Balled Museum Special, tree
Baited Sherman, tree
Small mammal trap placement at trap stations 1-16 located at 33-rn intervals
along a 500-rn transect in intensive sampling areas of the Columbia River
stuly area, 197't-1975.
I-
16
seient.
An IOA value for each captured species and
oup of species
was determined, for each o± the three traD station types (Fig. 2).
IOA value was calculated in the following manner:
individuals of a species or species
The
the number of
oup caught in
ound traps of a
particular trap station type during the first two sanpling nights was
divided by the number of star4axdized
ound traps of that trap station
type used during the first two nights.
This quotient was then multiplied
by a factor of 100 to obtain the IOA value for a species or species
'oup by a particular trap station type.
This calculation was made for
each of the three trap station types for all species and
oups of
species caught in each habitat within a senent.
A mean bA value for each species and species
oup in a habitat
was calculated from the IOA values for the three trap station types in
that habitat.
These calculated IOA values were used to compare the
relative abundance of the following species and.
oup of species among
habitats within each senent:
Deer mouse
Vaaz± shrew
Total mammals
Total mammals excluding deer mouse and vaant shrew
Insectivores (shrews and moles)
Insectivores excluding vaant shrew
-
Mice
Deer mouse
Pacific jumping raouse
Great Basin pocket mouse
Ord' s kangaroo rat
Western harvest mouse
Northern
asshopper mouse
House mouse
M1.ce excluding deer mouse
Voles (Nicrotus spp.)
17
A mean bA value for these species and
oups of species for each
of the study area was calcu.ated from the
segme
each habitat within a segment.
mean bOA values for
These IDA values were used to compare
the relative abundance of these species and. species
oups among segments
0± the study area.
Analysis
The three IOA values of a species or species gmoup for each habitat
within a segment were arranged in a randomized complete-blocI design and
tested with analysis of variance (Steel and Torrie 1960).
transformed with the '\JX + 0.5
The data were
transformation (Steel and Torrie 1960)
when 25 percent or more of these IOA values in each analysis of variance
test were zeros.
Differences in relative abundance of a species or
species gnoup among habitats were considered statistically significant
if P<0.05.
Tukey's w-procedure (Steel and Torrie 1960) was then used.
to test differences among habitat means.
These habitat means were arranged in a completely randomized design.
These
data also
were transformed when 25 percent or more of the
means were zeros.
habitat
Analysis of variance for six treatments (segments)
with unequal replications (habitats) (Steel and Torrie 1960) was used
to test for differences in relative abidance of the deer mouse and
vagmant shrew and the seven species
area.
ous among segments of the study
Differences were considered statistically significant if P <0.05.
Tukey's w-proced.ure was used to test differences among segment means
when the F-value was significant.
18
RULTS AND DISCtSSI0N
Thirty-nine species o± small niaanials were recorded in the study
area (Table 1).
All species were associated with intensive sampling
areas except the white-tailed jack rabbit, mountain beaver,
ay
sq.uirrel, and. gay-tailed vole which were identified in areas other
than those chosen for intensive sampling.
Twenty additIonal species
(Table 1) were not identified. during the study but may possibly occur
in or near the study area.
Many of these species, however, do not
occur at low elevations or are rare.
During the field. work, 11,019 trap-nights in intensive sampling
areas produced 1,982 small mammal captures.
Although 23 specis were
captured (Table 2), deer mice and. vaant shrews collectively comprised
81+.9 percent of the small mnairurials captured.
Seient
1.
0ccirence--Moist climatic condItions and. the resulting lush vegetation appear to be ideal for insectIvores which made zp one-third. of
the 18 small mammal species identified in seient 1 (Table 3).
Insec-
tivore species captured by Tabor (1977) occed mainly in damp habitats.
Ingles (1965:81) states that InsectIvores "on the Pacific Coast are
nearly all inhabitants ol' damp, moist' places."
Ten species of small mammals, whose ranges according to B'b and
Grossenheider (t96L.), Ingies (1965), Maser and. Storm (1.970), and. Verbs
(1971) include all or part of seaent 1, were not identified in this
senent (Table i).
These species, many inhabitants of coniferous
19
Snail naaina.Ls ocrir1 along the Colth1a 1ver. Sti.:r area aeçients listed, after
species represent :ane according to various authors.
'4erscoring .enotes
TABLZ 1.
QCO'.1CC
iX1
this st'y.
SpecIes
(Scientific Name) b
SpecIes
ange acd.
Occin'rence
Iagra.nt
(Sorex van)
I
USk73br9W
(S. obsc'.$)
1
1
(s
)°
(. beed.irii)
1
Trowbride's 3bZ9
2
2
(3. troubrid.g.t)
(Neotrichus
Towtseri' s nole
(Scaranus
Coast tale
Pika,
sii)
-
CanyOa nouse
(. crnitus)°
. 2
Northern grasshopper rtouze
(Onychomys leucoaster)
Dusky-footed woodrat
(Neotoma. fuscises)
Bushy-tailed wocd.rat
1
2
1
(Ochotona orinces)C
1
:
,
-
2
(Laus emericaiuz)
White-tailed, jack rabbit
(L. towrjer,d,ii)
Black-tailed. jack rabbit
.
Western red-backed vole
(C. occtdento,lIs)
Heather vole
6
(Phenacouys
-
2
intarnedius)C
MOrIt3.
-
h
4
(. longca14us)
(L. coraicus)1'
vole
(?icrotus nontarnis)
Gray-tailed. vole
Mountain beaver
(M. ajcaua)
(Alcdontta r1,'a,)
Lea.st cbipntunk.
(utania.s nininwa)
(. torserii)
(T. lorgicaus)
(L townsendii)
(c.
ellow-beUied. narnot.
(Marnota fiav-tventrjs)
Townser' s ground sq,uirrel
(SoerrnohiJ,uz townser4ll )
(3. norve.ous)
(S. latera.ijs)°
1
-
(. trtotatus)
-
(Mu.stela ermina)
Long-tailed weasel
, ,
(. frenata)
Northern pocket goner
(Thomomys alooides)
Rare (Olterman and. Terts
1965,
,
-
'
9
2
4
Cart.red In non-staardized. raos only.
Gbserved or Identified by sign.
Tot recorded. IA intensIve sanpllng arena.
hStatus
urdeternined.
1972).
2
-
ine(short-tailed wea.sel)
-
a(.Terts 1971, Maaer and. Storn 1970, LngJ.es
6
-
Western j.oping nouse
(Zaous orizinecs)
Pacific j'nming mouse
(ScI'.s caro1ner.ss)
Western gray scuirrel
(s. zriseus)r
7
House mouse
nusculu.$)
(
-
Dray squirrel
aL. 1975).
igh elevations.
6
Torvay rat
beechevt)
Gcld.en-fnaatled. grouz. squirrel
1561.1.).
1
oreor.i)
(Lagz'us c' atus)
3lack rat
(Rattus rattuz)
(,
Glaucontys sabrinus)
2
(Ar'ricola r±charIsorI)°
(s. vashiorij ) '
..
-
Sagebrl2szl vole
6
Ca.li±'orhia
(Taat.iaaci'z d.ou1asII)
Northern flying squirrel
2
Water vole
iashingtor. grourd so uiel
Dougl' sq.uirrel
.
Creeping vole
23
2
,
1
Long-tailed vole
Townse's
-
2
Townser.'s vole
- -
eUow-oine chjomuk
(I. amoenus)
Grossethelder
-
ihite.zooted vol
(P. a.lbises)
Red tree vole
/
,
6
.
(Cletonomys aver)
L.
..
1 '
Southern red-backed vole
1
astern cottontail
(S. fiortdanus)
Ni.ttail's ccttontaU.
(s. nuttaflii)
2
)
(i. cinerea)
1
3r'ish rabbit
(Jones et
4
(Rettcd.ontotiris nea1otis)
-
(3. crarius)
nod.
-
Deer nouse
(?eroinyscus nanlouJ.atus
townser4lt)5
Snowshoe hare
6
Western harvest jtouse
Merrian's snrew
(s. taerrtani)
Shrew.-fnole
2
jj)
(Dtd.c'rs
1
9 3
(T. buIbivors)
Great 3asin ocket nouse
(Pereathus ar'rjs)
Ord s kacgaroo rat
Water skew
Pacific water s'ew
Occence
Western rocket gopher
çThocnys
ta)
Caa ocket gopher
-
1
2
?.ange az.
(Scetific Nace)
1972).
(Olternan and. Ter-n
20
TABLE 2.
Total number of individuals of each mammalian species captied.
in stand.ardized ground. traps in intensive sampling areas of
the Columbia River study area in fall 1974 and sDring 1975.
Segment
Species
2
1
4
3
6
5
Total
Insectivora
Vagrant shrew
110
77
111
Dusky shrew
9
3
1
Pacific water shrew
2
2
Trowbridge's shrew
6
Coast mole
1
302
13
4
11
Shrew-mole
4
1
7
18
3
10
1
Rodent ia
Townsend's chipmunk
1
Northern pocket gopher
5
6
1
1
Ord's kangaroo rat
9
9
2
32+
36
1
1
33
35
247
263
338
1,381
1
1
5
14
3
10
Great Basin pocket mouse
Western hsvest mouser
Deer mouse
48
133
352
Northern grasshopper mouse
Bushy-tailed woodrat
5
Montane vole
7
Townsend's vole
5
Zng-tailed vole
Creeping vole
33
4
8
41
6
60
2
3
13
18
34
1
House mouse
Norway rat
Pacific jumping mouse
1
3
14
14
7
8
1
Carnivora
iine (short-tailed weasel) 1
Long-tailed weasel
Total
Trap-nights
1
2
232
1146
2
228
509
299
270
L1
1,863 2,436 1,746 1,014 2,814
1,982
11,019
21
ean index of abur4ance (caDtss oer tOO a?-rd..hts) values o
sma.11 sa.wsals in ha'oinats inventoried. in saiest I of the OcJ.usbia
TJ3LE 3.
iver study wea.
Habitat
3eachass
Species or
roixo
9.5
0.3
shrew
Pacifto water shrew
i'rowbri4e' s shrew
Ald.er
(2)
(3)
(396)
(38L)°
Vaast snrew
Dusky
ial arsh
(2Y
(366)
jj.Q
5.2
0.3
2.0
0.6
3 .0
S1ew-mole
0.3
0.2
Coast sole
3rush rabbit
0.3
1.2
C
Snowshoe hare
Towr,sez.' a chipmunk
0.2
.
Califori.a rcusd. squ±rsel
Doula.s' sq.uirrel
Deer souse
Townsend.s vole
Long-tailed. vole
Creeping vole
3.7
2.9
0.3
2.5
6.3
0.5
Pacific ji.sroisg souse
Short-tailed
3.5
d
0.3
0.6
Long-tailed. weasel
g
0.3
(TCA)
Thta.1. samma.ls
6.3
TCMA-d.eer souse'ivaast shrew
Insectivores
Iosectivores- vaastshrew
i6.
26.0
3.3
10.3
19.
9.1.
7.3
LLI..6
11.9
3.3
?fice
0.6
3.7
3.i.
6.3
6.6
7olaa
2.5
0.5
7.2
0.5
ce-d.eer souse
aThtensj.ve saroling areas were sanrled 2,
3
or
L.
ccnsecut1.ve
0.3
izhts in fall
consecutive nights is soring 1975, however, only the capte
data. ±''om the first 2 ni..ghts were used to ca.lculate captes per 100 trapnights because data from both seasons
intensive saroUng areas of sizsilar
197L
and. 3 or Li.
a.ed.
were comb med..
DTh.nnbers is
arentheses eciia.l thtanstve samoling areas of sisilar habitat.
is arerxtheses equal rar-nig±rts d'str.g first 2 nights.
dCaotl.d after aecor4 night.
CNct
cartred., out was observed. and/or
identified
by sign in thts habitat.
Capttred. in non-staardized traps only.
rot recorded. in thtansve saring areas, but was observed Is this habitat.
character sueracrjota denote significant d.ifferer.ces among habitat
scans at the 5 ercent level or less (a.naiysis of variance). The results of
the sean separation tests (Tukey s -prncethre) are d1.aamed. eanz u.erscored, by the same Lifle are not signifIcantly different.
Ald.er
6.8
3eachass
0.3
TIdaJ. ersh
0.6
22
forests, may occur in habitats other than those sampled in segment 1.
elative abundance--The vaant shrew, deer mouse, dusky shrew,
and shrew-mole were captured in alJ. habitats sampled (Table 3).
1ean
IOA value for the vaant shrew was higher in tidal marsh habitat,
whereas mean 1OA values for the dusky shrew, shrew-mole, and deer mouse
were
eater in Alder.
No species abundance, however, differed statis-
tically among habitats.
The gmoup insectivores excluding vagmant shrew was the only species
gmoup differing significantly in abundance among habitats.
This species
gmoup was significantly more abundant in alder habitat the' beachgmass
and tidal marsh (Table 3).
Alder is probably better habitat for these
insectivores due to the presence of many insects and other invertebrates
associated with a gmound cover of deep, moist litter.
Insectivores were predominant in all habitats sampled in this
segment.
They made up 63 percent of the total mammals captured in
beachgmass habitat, 56 percent in tidal marsh, and 61 percent in alder.
Senent 2
ccirence--Seventeen species of small mammals were id,entified in
habitats sampled intensively in segment 2 (Table 4).
Three additional
species were identified in tes of habitat other than those sampled
intensively:
the snowshoe hare and mountain beaver were found in
maple/'Douglas fir, and Douglas
squirrel was observed in alder.
Aarently environmental conditions are almost as advantageous for
insectivores in segment 2 as in segment 1;
one-fourth of the 20 small
mammal species found, in segment 2 were insectivores.
23
TABLE Li..
(caotures cer 1.00 trap-rihts) values of amail sammala in
habitats inventoried in aeaent 2 of the Colunbia. River stu±f wea.
abitat
Mean ind.ex of abt
Tid.al
Sth
Cotton-
Tid.aJ.
Reed
Tidal
Mah
(4)b
willow
(Li.02)°
(174)
(249)
(288)
(192)
(2)
(298)
1Taaat sbrei
4.3
1.7
3.0
1. .2
3.8
3.1
2.7
9.0
Pacific water sgw
Trowridga' skxev
0.5
1.1.8
1.4.3
0.5
1.5
0.3
0.3
Species or roup
(2)
Dusky strew
Sieka
Spruce
CottonWOOd
(2)
(3)
Tow zezs o1e
e
a
a
a
a
a
a
Brush rabbit
st cottona..3.
TownseOd' a chipmunk
Deer nouseb
TownseOd's vole
5.4
Long-tailed. vole
Creeping vole
tarway rat
Pacific ji.mrping noune
Long-tailed weasel
(TMA)
Total ma1
TOMA-dear mouse #vaan't skew
Thsectivores
tsetivoras - vaant shreW
Mice
0.6
1.0
0.4
0.6
0.4
17,0
0.2
(t)
itllow
1.0.7
1.0
4.9
paSs
(2)
(270)
a
a
0.3
2.4
1.7
0.5
5.6
0.3
Mica-deer mouse
iC.low
Can-
g
a
California
squirrel
1orthern flying squirrel
wood/
21.Z
1.2
4.2
1
0.6
6.2
1.4
15.3
3.8
18.5
1.5
10.1
0.8
3.1
2.7
9.0
1.0
1.1.3
14.3
0.3
1.4
0.5
1.5
0.3
0.5
.2
17.0
Voles
Thtensive samolizig wea.s were sanpied 2, 3 or Li. consecutive nights in fall 1974 and 3 or
consecutive nights In spring 1.975, however, only the captte data from the first 2 nights
were used, to calculate ca.ottzea per 1.00 trap-nights because data from both seasons and intensive sa]..thg areas of sisilar hattat Were combined.
bNbers in arentheses equal intensive samp1.ng areas of sinilar habitat.
in erentheses equal trap-nignts thring first 2 nights.
dCated. after second. runt.
Tot caot.red, but was observed. and/or td.entifie by sign in this habItat.
:Cttzd. in non-standardized trans on.ly.
ot recorded, in intensIve sampling areas, but was observed in this habitat.
Touble character auoeraipts denote sIgnificant differences amor.g habitat teans at the 5
percent level or lass (analysis of varla.nce), The results of the team separation tst
(Tukey a -proced.tre) are diaamed.. Means underscored, by the sane lIne are not signifIcantly
different. Means und.erscored. by the sane dotted line &iffer by exactly .
Reed.
9.0
bb
Marsh
L1..3
Dottonwood/
Tidal
(W.ow
Sitka Spruce
17.0
°
Tidal
TIdal
Sitka oruce
21.2
1.4.3
Cottowod/
iillow
18.5
Cottonwood.
3.3
iillow
3.1.
Tidal
iU,low
11.3
tllow
15.3
Marsh
5,4
Tidal
Marsh
1.3.7
Tida.].
Sitka. Scrca
3.0
Cot-touwood/
tllcw
2.7
T1.dal
T1.da.i.
3ub Jillow
1.7
Reed.
Cottonwood. 3ub willow Canarya.ss
1.0
Reed.
Canaryasa
10.1
0.6
3.3
TIdal
ottonwocd Sith willow
6.2
2.4
2L.
T.BLE
Li.,
oritnued
T4a1.
seed.
Ca.arçzs
9,0
ce
Tida.L
SLtka Soruce
t7.0
ski
Sitka Spruce Cottonwood.
Jillow
2.7
Li..9
Cottwcd./
iUiw
1L.3
.daJ.
iUow
Cttotwood/
Maz'i
Cottonwood
5.6
1.0
Ta1
Sb tUow
T4a1
aeed
0.6
0.3
Shb Willow Canary.s
Ten small mammal anecies, whose ranges totally or -artiaily include
senent 2, were not found in this segaent during the study (Table 1).
Three of these species, the shrew-mole, coast mole, and short-tailed
weasel, were found. to occur in this senent at the Trojan Nuclear Power
Plant site (RN 72) during a study conducted by Battelle, Pacific Northwest Laboratories (197L.).
The other seven species (i.e., western and.
Camas pocket gophers, bushy-tailed woodrat, southern and western redbacked voles, white-footed vole, and. red tree vole) may occur in habi-
tats not sampled in senent 2.
The voles we inhabitants of moist
coniferous forests (Maser and Storn 1970).
One record of the white-
footed vole in this senent was reported for 7 miles southeast of Rainier,
Columbia County, Oregon (RN 7+) by Olterman and Ver-ts (1972).
Maser
and Storm (1970:69) state that this species is 'the rarest maicrotine
rodent in North America."
Relative abundance--The vaant shrew and, deer mouse were trapped
in all habitats sampled (Table !.).
Both species differed significantly
in abundance among habitats.
The va'ant shrew was significantly macre abundant in reed, canary-
ass habitat than in willow, tidal Sitka spruce, cottonwood/willow,
and tidal shrub willow (see miieazl separation results, Table L).
highest
The
OA values for the vaant shrew in seaent 2 occurred in reed.
caryass and tidal marsh habitats possibly indicating a preference
for non-forested habitat.
It also may indicate the
eater tranability
of vaant shrews in habitats where deer mice were not abundant as was
the case in reed canaryass and tidal marsh.
by
Vaant shrews collected
hitaker and Maser (1976), however, were found in non-forested areas.
26
In contrast to the vaant shrew, the deer mouse had. the lowest
mean bA value in reed canaryass habitat.
Deer mice were most abun-
dant in tidal Sitka spruce, cottonwood/willow, and..wilow habitats which
did, not differ significantly in deer mouse abundance;
deer mice were
significantly less abundant in tidal marsh, cottonwood, tidal shrub
willow, and reed canaryass (Table Lb).
Three
oups of species (i.e., insectivores, mice, and total
manm.als) differed significantly in abundance among habitats.
Insect i-
vores and. mice were principally represented by vaant shrews and deer
mice, respectively, and. therefore abundance differences for both species
gno ups were similar to differences for both species.
Total ma.mxnaJ. abun-
dance, as deer mouse abundance, was not significantly different among
tidal Sitka spruce, cottonwood/willow, and, willow habitats (Table L).
Insectivores, mainly vagnant shrews, were
redominant in three
habitats, whereas mice, principally deer mice, predominated in the
remaining four habitats.
Insectivores made up 89 percent of the total
mammals captured in reed canaxygi'ass habitat, 71 percent in tidal shr'.b
Mice composed 52 percent of the
willow, and. 61. percent in cottonwood.
total mammals captured in tidal marsh habitat, 80
spruce, and. 77
ercent in tidal Sitka
ercent in both willow and cottonwood/willow.
Seçnent 3
Occurrence--In this seient 13 small manunal species were found. in
nactats samledr..-tensvely (Taoje
).
Iricio.ental observations of
three additional species were made in types of habitat other than those
sampled intensively.
Townsend' s chipmunk and. Douglas' squirrel were
27
TABLZ 5.
!ea isdex of abu ance (captures per 100 trap_.r1ita) values of 5911 oasjnals is
habitats ventor1ed is seert 3 of the Coluba 3iver study area.
:abitat
Ash/
Cotton- Cottonwood./ iUow/
wood..
Willow
Cottonwood
(3)0
(j)
(3)
SpecIes or Grou
7aat shrew
Ousky shrew
Shrew-mole
'owr.zend,'s sole
OUnd
(3814.)
(3614.)
(3611.)
6.2
11..3
5.3
3.7
2.3
0.3
1.11.
C
C
C
C
squirrel
C
£
squirre].
Northern flytn squirrel
Ceer souse
Townsend's vole
Long-tailed, vole
16.3
0.9
2.2
0.6
Total saawiai.s°° (TOMA)
23.5
29.0
2.8
tong-tailed. wesal
TOMA-deer souse +vaant strew
Zosectivores
Ensectivores - vWant shrew
Ioles
()
(390)
(j)
(L1.62)
Gray
- deer
()
Shrub
Willow
Willow
0.3
Sastern cotthtail
Mice
sss
(L4.32)'
Srush rabbit
Californi_.a
Canary-
tou.se
22.0
5.8
1.8.0
2.14.
2.14.
1.9
1.6.8
23.0
1.0.14.
16.3
22.0
21.2
0.3
5.6
0.3
15.2
0.9
2.3
0.5
0.9
6.2
11..3
aThtensive samnlisg areas were saspled 2, 3 or
consecutive nights is anring
0.5
1.5.2
L
.2
8.7
2.7
2.6
1.9
1.11.
5.8
13.0
.2
2.14.
2.14.
1.9
2.14.
consecutive nights is fall 19714. arid
3
or
however, only the caoture data from the first 2 nights
were used, to calculate ca;tes er 100 trao-n.t.ghts because data front both seasons and Intansive sanmling areas of sLsilar habitat were combined.
in oarertheses equal intensive samplIng area.s of aislar habitat.
1.975,
:rbers is parentheses equal trap-nights ding first 2 nights.
dCaDted in ion-standardized traps on.ly.
Tot caotured, but was observed and/cr i4ent .ed. by sign is this habitat.
Tot recorded is 1rten.sive sampling areas, but was observed is this habItat.
Touble character supersortpts denote signifIcant differences anorig habitat aea.ns at the 5
percent level or less (analysts of vartance).
e results of the teas searatton tests
(Tukey' a w-procedure) are itaaned. Means underscored, by the same line are riot signifIcantly
dferezrt.
l.sh/WUlow/
Cottonwood/
Willow
Willow
22.0
18.0
Willow
Cottonwood
Willow
29.0
Cottonwood
23.5
23.0
21.2
Cottonwood, Cottonwood
1.6.3
15.2
Ash/Wiilcw/
Reed
Shrub Willow Ca.nsryra.ss
7.2
5.3
Reed
Casaryass Shrub Willow
1.6.8
28
observed in maple/Douglas fir, and the
ay-tailed vole was found in
aicultural lands.
Sampling methods, limiting the inventory to riparian habitats, and.
the low vegetative diversity among these habitats may explain why jL
f
the 30 small mammal species whose ranges include at least part of
senent 3 were not encountered (Table 1).
Relative abundance--The vaant shrew, deer mouse, arid Townsend' s
vole were trapped in all habitats sampled (Table
.5).
The mean 1OA value
for the vaant shrew was highest in reed canarygtass habitat as in
senent 2. Mean bA values for Townsend.' s vole were highest in reed
canaryass and. willow, whereas the mean deer mouse bA value was highest in cottonwood/willow. Only the deer mouse, however, differed sig-
nificantly in abundance among habitats.
The lowest deer mouse bOA values, as in segnient 2, were recorded
in shrub willow and reed canaryass habitats. In senerit
3
these bA
values were significantly less than deer mouse IOA values in cottonwood
/willow and willow habitats (see mean separation results, Table
The structural dissimilarity of the two
5).
oups of habitats, forest and.
non-forest, may account for this difference. :iedlund and. Rickard. (1976),
studying small mammal poulations near the Trojan Nuclear Power Plant
(R'i 72) in senent 2, captured fewer deer mice
ifl
meadow than in forest
habitat.
Two species
oups, mice and total mammals, were significantly
different in abundance among habitats. Because deer mice were the
mice in that species
only
oup, abundance differences among habitats were
the same as for deer mice. Total mamzaal abundance in cottonwood/willow
29
habitat was significantly
eater than shrub willow (Table 5).
amount of sinai.]. nianunal microhabitat (e.g.,
The
ound cover, runways, holes)
was less and frequency of inundation from water fluctuation was
in shrub willow than the other habitats.
eater
These two factors may account
for the lower total mammal abundance in shrub willow habitat.
Deer mice made up a substantial amount (66-78 percent) of the total
mammals captured in all habitats except reed canaxyass. Vaant
shrews composed 52 percent of the total mammals captured in reed canaryass habitat.
Seient L.
Occurrence--Twenty small mammal species were identified in senent
Li. (Table 6).
Species from west (e.g., Pacific water shrew, shrew-mole,
Townsend's vole) and east (e.g., Muttall's cottqntail, yellow-bellied
marmot, northern pocket gopher, western harvest mouse) of the Cascades
occurred in this area of transition from niesic to xeric cor4itions.
According to Burt and. Grossenheider (1.9 6L4.), Ingles (1.965) and Maser
and Storm (1.970), ranges of the dusky shrew, mountain beaver, creeping
vole, Pacific jumping mouse and short-tailed and long-tailed weasels
include all or part of seient Li..
found in this senent.
These species, however, were not
Nine additional species whose ranges include at
least part of senent Li. were not recorded during this study (Table 1).
These species may possibly occur in this segnent, but many are known to
occur only at elevations higher than that of the study area.
Relative abur4ance--Only one species, the deer mouse, was captured
in all seven habitats, and it differed significantly in abundance among
30
TABLE
6.
Neazl tr4ex of abudacce (catures per 100 trap-ci.ts) values of ssa.U. nammals
habitats izvenorted th seect 14 of the Coluahia iver study wea.a
n
:-aitat
Dou1as
Shrub
W.ilcw
tilow
Fin
Male
Species or Gro
(4)b
(342)°
(96)
7aant shrew
0.7
C
1.1
0.6
O9
1.6
Shrew-sole
0.2
1.6
Pacific water shrew
owhrjd.e's shrew
Coast aole
1utt all' s cottontail
Snowshoe hare
Townzond.'s chipmur.k
(t)
(z)
(252)
Oak/
?o.erosa
Pine
(2)
(270)
Oak
(2)
0.ssla
(2314)
(2)
(168)
sock
i;-Rip
(2)
(3814)
0.5
0.14
Uow-bel2.ied sarmot
California ouud. squirrel
Weeterm
ay squirrel
Oou%las squirrel
toz-thern f1ytn squirrel
Nbrthern pocket gopher
0.3
0.5
Western haest touse
Oeer sue
3.7
3ushy-tailad. woodnat
Montane vole
3.1
1.2
Townsend.' s vole
tcng-ta.tled. vple
15.4
0.3
6.14
0.8
Lsecttvorss - vaant
screw
1 .5
Mice
3.7
Tolee
6.3
Mice-'eer souse
26.3
0.5
1 .6
1 .3
33
12.9
Total sanmals°° (MA)
lMk-deer nouse+vat shrew°° 8.5
2.1
tnsecttvores
2540
114.14
e
14.3
13.9
6.3
0.14
1.1
3.5
1.6
3.1
15.14
1 .6
0.4
0.4
6.4
e
15.7
0.8
0.5
27.5
2.6
26.3
114.14
25.3
0.5
1.6
26.3
0.5
azrteflsive sampling areas were sampled 2, 3 or 14 consecutive nights in fail 1974 and 3 or 14
consecutive nights in spring 1975, however, only the oate data. from the first 2 nights war,
used, to calculate capttmee per 100 ap-.raghts because data from both seasons and. tnansive
habItat were combined.
sampling areas of
bNbars in parentheses equal intensive sampling areas of similar habitat.
Ttbers in parentheses equal trap-nigh-ta thm'ing first 2 nights.
ot canted, but was observed and/or Identified by sign in this habitat.
ot oartzed. until third night.
:\0t recorded. in intensive sampling areas, but was observed. in this habitat.
Captz.ed in non-staard.ized traps only.
Double character superscripts denote sIgnificant d.ifferences among habitat nean.s at the 5
percent level or less (analysis of variance). The results of the sean separation tests
(Tukey' a w..prccedune) are d.ia.amed.. Means uarscored by the same line are not signifIcantly
d.iffar,nt. Means underscored. by the same d.oted. line differ y exactly w.
sock
Oak,'
Couglas tn/
RIp-Rap
26.3
Orassland
27.5
Orassland,
25.0
Maple
15.14
Rock
Douglas Fir!
Rip-Ran
Maple
26.3
13.9
Oak
114.14
Oak
15.7
Ponderosa Pine
6.14
Willow
12.9
Willow
Willow
3.7
3.1
Oa/
Por4erosa Pine
6.3
Willow
14.3
31
r.Bz
6.
Conttnued
Dou1a.
'/
Grass.ar4
Oak
Ri?-Rap
3.5
2.6
0.3
0.5
ouia.s Ft
'a1e
t.6
Rocc
26.3
Rock
a.o1e
sock
Oac/
t2.2.ow
t.5
Graas1a..
25.5
?or4erosa Ptze
O..
Oak
0.0
Dou1a3 t/
t5.
Oak/
Oak
t
0ou1as fl.r/
Willow
6.3
Gr3.ss1a
t.6
3.0
Oak
0.0
0.0
Gras1ath
0.0
?oiderosa Pte
ifl.flow
6.
3.7
oak/
ap1e
Caic/
ocd3resa ?izie
0.
?or4eresa ?ire
0.0
Jti.olf
0.0
3hb
3.0
Rock
R±-Rap
0.0
WU.icw
0.0
32
some of those habitats (Table 6).
Siprisingly, rock rip-rap habitat
had. the highest mean IOA value for deer mice in this senerit.
ition also occurred in senents 5 and 6.
This sit-
It is not known what food.
soice supports such apparently high numbers of deer mice in this land.
form class, which bordered railroads or highways on one side, the river
on the other, and. is essentially devoid of vegetation.
Five species gnoups, total mammals, total mammals excluding deer
mouse and vaant shrew, insectivores excluding vagnant shrews, mice,
and voles, differed significantly in abundance among habitat (Table 6).
Significant differences in total mammal abundance among habitats were
very similar to those of deer mice because deer mice were predominant in
all habitats except willow.
Willow habitat had the highest mean 1OA
value for total niainsnals excluding deer mouse and. vaant shrew because
of the voles and other insectivores captied in willow.
western harvest mice in
in that species
Except for
assland habitat, deer mice were the only mice
oup, and differences in mice abundance among habitats
were very similar to those of deer mice.
Vole abundance was gneatest in
willow habitat which had. a ground. cover of moist litter and, a dense
ur4erstory of reed, canaxyass to provide food. and cover.
Deer mice made up most (7L-98 percent) of the total mammals captumed
in all habitats except willow (29 percent).
Voles composed 53 percent
of the total mammals capted in. willow habitat.
Te.'art shrews,
although present in this senent, decreased. in abundance probably due to
the more xeric conditions in seinent L4.
33
Segment 5
Occurrence--Species richness was lowest in segment 5;
oniy nine
small rnaiiunal species were iden±ified (Table 7).
Eighteen additional species whose ranges are totally or partially
inclusive of segment 5 (Burt and Grossenheider
Ingles 1_965, Verts
1971, Maser and. Storm 1970) were not recorded (Table 1).
During this
study, however, 11 of these species were found in segments other than 5.
Relative abundance--The deer mouse was captured in all five habitats (Table 7).
Mean IDA values were highest in rock rip-rap and shrub
willow, but there were no significant differences in deer mouse abundance among habitats.
Rock rip-rap habitat had the highest abundance
values for deer mice and nearly no vegetative cover;
uation existed in both segments L
an identical sit-
and 6.
Because deer mice made up most of both total ma.mivals (9Li._100 per-
cent) and, mice captured tn all habitats, there were no significant d,if-
ferences in abundance of any of the species gmoups among habitats.
The predominance of deer mice, an early invader species c± disturbed
areas (Dasinarin
1964:324W),
and very low species richness may be due to
filling of The Da.11es Pool (segment 5) in 1965 and resulting permanent
loss of ectensive amounts of diverse floodplain and. riparian habitat.
Segment 6
Occurrence--'1ineteen small mammal species were ideniified in
segment 6.
Of these species, 16 occurred in types of habitat sampled
intensively (Table
).
A road-killed white-tailed, jack rabbit '.as found.
34
TABLE 7.
ap.-rjts) values of
of the Coibia River stu area.
Mean. index of abn"diire (captures per 100
hai.tat.s iavazltorLecj La seea
3
samnals La
Habitat
Rbbitbrush
Secies or Group
(2)b
(223)°
Rockcli±'f
Grassland
(2)
(162)
Sib ifl.ow
(1)
(102)
i1tLlow
(1)
(18)
d
Tu'ttall' a cottonta.il
3lack-tailad jack rabbit
'fellow-bellied tartot
Ca.lifornia ound squirrel
Rock Rip-Ran
(2)
(3EL)
e
£
Northern pocket o?her
Great 3a.sia ocket aouse
Westarr harvest aouse
jeer nouse
/
1 .2
0.3
23.3
17.L.
30.0
25.0
3ushy-tai.ted. woodrat
(tMA)
'Ibtaj nmm1
TCMA-d.eer ouse
23.3
18.6
1.2
30.0
25.0
30.5
1. .0
31.3
Mice
23.3
18.6
30.0
25.0
30.3
M.tce-deermouse
1.2
1.3
0.3
consecutive oights La fall t97& a.r4 3 or
2, 3 or
consecutive nihta La sprtn t975 however, on.ly the capttze data from the first 2 rihtz
were used to calculate captures per 100 tra'p-rlihts because data from both seasons and Laterisive saatplin areas of similar habitat were combined.
bN=bere La parentheses equal Later..si'te samplia areas of similar habttat.
La parentheses equal trap-nights during first 2 aights.
Tot captured, 'out was observed and/or identifLed by sign La this habItat.
ot recorded La thtenslv. sampling areas, brt was observed La this habitat.
camtured in non-standard.i2ed sps only.
3Thtensive saznplicg areas were sampled
Tot cantured until third iiht.
8.
fALI1.t
Mean index of abuiidancc (tures er 100 trap-nights) values
Itiver study area.
of
sivall wauuuals in t hutats inventoried in segiucot 6 of the Coluiubia
Habitat
Kock1iff/
Sage-
Rabbit-
bitter-
6rass-
Cottonwood/
Talus
(2)
(288)
Ctassland
(2)
brush
(2)
(384)
brush
(2)
(384)
land
(2)
(384)
Willow
(2)
Marsh
(264)
brush
(2)
(252)
(198)
(312)
(l6)
d
4
d
4
4
4
e
4
4
4
4
e
e
c
a
0.4
2.0
3.6
1.5
4.8
0.4
07
Rock
Rip-lIsp
(1)b
(192)C
Species or Croup
Nuitalt's cottontail
d
White-tailed jack rabbit
black-tailed jack rabbit
Yellow-bellied Miarwot
lowiusend's ground squirrel
Nor the in pocket gopher
(reat Ilasla pocket mouse
keuigai-uo rat
Western haXust Iaoti
Ileur mouse
No rthemn gm saluopper mouse
llussluy-Lailed woodrat
4
33.3
32.6
29.4
1.0
0.7
0.4
28.0
24
0.2
1.4
3.9
2.0
0.8
3.0
3.4
0.3
1.1
8
house mouse
ls
uuian
(tUNA)
MIce44
Mice-deer uiuuse'
(1)
d
Nuiwny tat
10t4A-dei
Olive
1.8
1.3
0.3
Montane V&)1e
Total ujoji
(2)
4
California ground squirrel
Ord's
4
Itussian
33.3
33.3
33.6
1.0
32.6
30.5
1.1
29.8
0.4
30.4
6.8
10.3
2.5
3.8
6.9
30.4
2.5
6.8
3.8
10.3
6.9
1.6
1.3
1.6
1.3
5.6
4.0
5.1
3.6
2.6
9.3
8.1
8.6
7.4
d
4.2
3.6
9.6
9.6
54
5.4
Intensive saumpling areas were sawl)led 2, 3 or 4 consecutive nights in fall 1974 and 3 or 4 consecutive nights in spring 1975, however, oniy
the capture data (rout the first 2 uuights were used to calculate captures P 100 trap-nights because data from both seasons and intensive
SLmuupliuug areas of similar habitat were combined.
tHuatbers in parentheses equal intensive sampling areas of similar habitat.
Nnabe,-s in parentheses equal trap-nights during first 2 nights.
captured, but was observed and/or ideuutified by sign in this habitat.
CCaptuI red in muon s tamuda rd zed traps only.
Hot recorded in intenstvti saupling areas, but was observed in this habitat.
SNot captured uimit 11 thi id night.
C.)
th
TAhL
8.
Continued.
aa)OUblO chaiacter superscripts denote significant differences among habitat means at the 5 percent level or less (analysis of variance).
The results of the wean separation tests (Tukay's w-procedure) are diagramed. Means underscored by the same line are not significantly
different.
Rockcliff/
Rock Rip-Rap
33.3
Talus
32.6
Talus
33.6
Rock Itip-Rap
33.3
Grassland
30.5
Russian Olive
9.6
Marsh
8.1
Bitterbrush
6.9
Itock Rip-Rap
33.3
Talus
32.6
Sagebrush
30.4
Grassland
29.4
Sagebrush
28.0
Bitterbrush
Sagebrush
30.4
Ritterbrush
Rockcliff/
cc
d&l
Coltonwood/
Willow
4.0
ltockcliff/
Grassland
29.8
Ce
Marsh
7.4
llitterbrush Russian Olive Rabbitbrush
6.9
5.4
3.8
3.4
10.3
Cottonwood/
Rabbitbrush
3.0
Willow
Marsh
1.5
1.3
Russian Olive
9.6
Marsh
kabbltbrush
6.8
Rabbitbrusli
3.8
Sagebrush
flitterbrush
Marsh
10.3
25
8.6
3.6
Sagebrush
2.5
Russian Olive
0.0
Cottouwood/
9.3
Grassland
1.3
Rockcliff/
Grassland
1.1
Rabbitbrush Russian Olive
6.8
5.4
Cottonwood/
Willow
Grassland
0.3
Grassland
1.3
Willow
5.6
Talus
1.0
Cot tonwood/
Willow
5.1
Grassland
1.6
Rock Rip-Rap
0.0
Grassland
1.6
Rockcl I ff1
Grassland
0.4
Talus
0.0
Rock Itip-Rap
0.0
37
on the ashinon shore in rabbitbrush habitat.
Because of concentrated
a'icultural practices and rodent control proaras in the white-tailed
jack rabbit' s optnu habitat, this species has declined in numbers and
is considered a rare mammal in Washington (Lauckhaxt 1970).
The short-
tailed weasel was observed in aicultural lands, an area not spec if
cally sampled.
Skulls of the long-tailed vole and vaant or dusky
shrew (B. J. Verts 1978, Oregon State University, personal communication)
were found in barn owl (o alba) pellets collected at a nest site in
marsh habitat on the Irrigon Wildlife Nanagement Area (RN 283-286).
Addltional species found in the pellets (e.g., Great Basin pocket mouse,
Ord's kangaroo rat, northern pocket gopher) indicate that the owls
foraged in nearby shrub-steppe habitats.
However, the nest location
and habitat requirements for the long-tailed vole and Sorex suggest
both were captured in marsh habitat.
Ten species, whose ranges include at least part of segnent 6
according to Burt ar4 Grossenheider (1961.i.), Ingles (1965), and. Verts
(1971), were not recorded in this senent (Table 1).
Absence of prefer-
red habitats and. sDecies rarity may exclude many of these species from
the study area in senent 6.
Relative abundance--The deer mouse was captured
n all habitats
except Russian olive, the only habitat in the entire study area where
deer mice were not captured.
As in segnents Lk and 5, deer mouse bA
values were highest in rock rip-rap habitat.
Deer mouse bOA values
were not significantly different anong bitterbrush, rabbitbrush, cottonwood/willow, marsh, gnassland, and. Russian olive habitats, but were
significantly lower than OA values of deer mice in rock rip-rap, talus,
38
rock clisland, and sagebrush habitats by at least a factor of 3
(Table 8).
Loose, sandy soil arid aridness of 'citterbrush, rabbit'orush, and
assland habitats may be factors limiting deer mice abundance in these
habitats. Kritzman
tiona].
(t97L.)
and O'Farrell
(1975),
working along an eleva-
adient in the shrub-steppe region of eastern Washington, found
deer mice less abundant on arid, desert floor than at higher elevations.
Because deer mice prefer rocky areas arid, cooler soil temperatures for
itzman concluded the deep, loose, dry soil cf the
shallow buows,
desert floor may be a limiting factor in deer mice distribution and
density. Greater soil moisture and, moisture availability at higher
elevations (31 deer mouse captures per 1.00 trap-nights at
1,070 m)
compared to the desert floor (three deer mouse captures per 100 trap-
nights at 150 m), led. 0 'Farrell to conclude that lack of succulent veg-
etation or free water at lower, more arid, sites possibly limits deer
mice abundance.
Probably both edaphic conditions and available moisure
in bitterbrush, rabbitbrush, and.
assland habitats are important
factors restricting abundance of deer mice.
Low deer mouse abundance in cottonwood/willow and marsh, and no
deer mice in Russian olive habitat is possibly the result of interspecific competition. Competition for similar resources may exist in
cottonwood/willow habitat between deer mice and western harvest mice and
in marsh habitat between deer mice and both- western harvest mice arid.
house mice.
Sheppe
(1.967)
for4 each species, deer mice and house. mice,
most abundant in places where the other. was least abundant and suggested
mutual ei1uzion as the possible reason. Competitive exclusion of deer
39
mice by house mice was found in additional tests (Sheppe 1967).
Irrigation runoff canals were established through the Russian
olive sampling area and. produced a dense, lush vegetative understory.
Surprisingly, deer mice were not caught in this habitat.
Overwhelming
direct competition from other opportun±stic foragers, western harvest
mice, house mice, and particularly Norway rats, may exclude deer mice
from this area.
Western harvest mice, house mice, and deer mice,
although low in number, were present in Russian olive habitat along the
McNa.ry Reservoir of the Columbia River in Washing-ton;
not captured (Asherin and Claar 1976).
Norway rats were
On Miller Sands, a island of
dredged material in the lower Columbia River (RN 24, segmient 2), four
Norway rats and, one deer mouse were captured in 1, 5LJi. trap-nights of
effort (1oodwa.rd-Clyde Consultants 1978).
San
A subseq,uent study on Miller
produced 20 Norway rats and no deer mice in 7,328 trap-nights of
effort (Crawford. and Edwards 1978).
Interspecific competition may
limit deer mice abundance, however, low abundance estimates may simply
reflect habitat preferences of deer mice.
Significant and non-significant differences among habitats for
total mammal and. mice IOA values were the same as those for the deer
mouse (Table 8).
Mice were predominant in seent 6.
They composed 91-100 percent
of the total mammals captured in all habitats except Russ±an olive (56
percent).
Gecaphic Distribution
The deer mouse was the only species captured in all seients of
L.0
the study area.
California gmound squirrels were also widely distrib-
uted., occurring in al]. segments (Table 1) and thus ecbending their
known range (Armstrong 1962, Burt and Grossenheider t9624, Ingles 1965,
Yerts 1971) eastward into segments 5 and 6.
Mice ware captured. in all segments, and differences in abundance
were significant between segments 5 and. 2 and between 5 and. 1 (Table 9).
Nice, essentially all deer mice, were most abundant in segment 5, where
they comprised. 99 percent o± the mammals captured.
In segments 1 and 2
mice were less predominant, 22 and 60 percent of the total mammals captured, respectively.
remainder.
Insectivores and voles accounted for most of the
Mean bA value for mice was lowest ifl segment 1, whereas
insectivore and vole mean IDA values were highest in that segment (Table
9).
Mean IDA values for deer mice were not statistically different
among segments, however, the highest mean (segment 5) was nearly six
times gm'eater than the lowest mean (segment 1)(Table 9).
Deer mice,
which were nearly the only mice captured in the first five segments,
increased in &oundance from segments 1 to 5 and then decreased in
segment 6.
The same pattern was evident for the percentage of deer
mice in the total mammal catch.
The increase from west to east in this gmanivorous and omnivorous
species may be associated with increasing seed availability, eastward.
Due to higher vegetative biomass in the west, seed production is no
doubt gmeater there than in the east.
Long
owing seasons, rapid
germination, dense vegetation, and d.eeD litter in the west could make
seeds more difficult to obtain than in the east, where the opposite
L.1
Mean index of abundance (captes per 100 traD-nights) values
of amall mammals in seiients of the Oolumaoia River study area
TABLE 9.
d.uring
t971.4, 1975.
Se'aent
Species or Group
2
1.
Insectivores ,
Vaant sh.rew
3
5
6
0.0
0.0
0.0
0.0
a.
Insectivores - vaant shrew C
Mtced
12.3
.2
Li..8
9.6
3.9
L4.7
2 .7
0 .2
0 .1
7.2
7.2
0.0
0.6
12.1
0.9
lLi..1
4..6
Deer mice
L..3
Mics-'jeermouse'
0.3
VO8S
3.L.
Total inaa.s (TOMA)
TOMA-deer rriouse+vaant
20.6
6.7
1LL..1
0.0
1.8
20.7
1.9
0.8
0.3
0 .5
13.5
13.5
0.1
1.2
16.1
2.3
0 .0
0
.0
25.5
25.2
16.5
13.3
0.3
0.0
3.1
0.1
17.1
25.7
0.5
3.8
aSerscrjpts denote significant differences among seient means at the
5 percent level or less (analysis of variance). The results o± the
mean separation tests (Tukey's w-procedure) are diaranied. Means under-
scored by the same line are not significantly different. Means underscored by' the same dotted line differ by exactly w.
1
2
3
6
5
L3
Lk.2
12.3
0.8
0.0
0.0
2
Li.
4.7
3.9
0.3
4
0.5
2
3
5
6
0.2
0.1
0.0
0.0
2
1
1
13.)
7.2
3
9.6
C1
2.7
5
2).)
e6
10.)
3
5
0.0
6
0.0
.0
4
3
2
3.1.
0.3
0.3
0.1
0.0
0.0
3
6
5
1.8
4
1.2
2
3.4
0.6
0.1
0.0
1
6'
6.7
3.8
L
3
2
5
2.3
1.9
0.9
0.5
conditions occur.
The increase in deer mice abundance might
reduced habitat diversity in the east.
so be attributed to
Loss of riparian and floodplain
habitats caused by reservoir construction and filling and the frequent
inundation of remaining riparian areas due to dam operations drastically
reduced shoreline vegetation and diversity in the Bonneville Pool
(segmer.t Li.), John Day Pool (segment 6) and particularly The DaIJ.es Pool
(segment 5).
This disturbance and resulting reduction in vegetative
diversity may account for the increase in deer mice, an early invader
species, in these disturbed areas.
Small mammal richness was lowest in segment 5 (nine species) and is
possibly associated with reduced riparian vegetative diversity caused by
the dams and their operation.
The decrease in deer mice abundance in segment 6 may be riated to
habitat selectivity by deer mice and possibly to the combined effects
of interspecific competition between deer mice and. other
and. omnivorous small mammals.
soils (critzman 1971k) with
anivorous
Deer mice preference for shallow, rocky
'eater available moisture and moderate
temperatures (O'Farrell 1.975) limits their abundance in sortie habitats
in segment 6.
Great Basin pocket mice, Ord's kangaroo rats, western
harvest mice, and. oarticularly house mice and Norway rats may compete
with deer mice for similar resources, thus suppressing deer mouse
abundance in. habitats where these species occur together.
Mice excluding deer mice were signifoantly macre abundant in
segment 6 than all other segments except 1 Arid, and semi-arid conditions and. deep, sandy soils are PrefezTed by the heteromyids (ingles
413
1965, :itzman 1974, O'Fefl 1975) and occur in the eastern portion
of segment 6.
Insectivores were captured only in the first four segments and.
geognaphic differences in insectivore and vagmant shrew abundance were
auoarent (Table 9).
Insectivores, vagnant shrews, and insectivores
excluding vaant shrew were significantly more abundant in segment I
than the other segments.
east.
Insectivore abundance decreased from west to
A positive relationship appears to exist between insectivore
abundance and mosture.
Annual precipitation in segment 1 is nearly 70
percent more than in segments 2 and 3, four times as much as segment 4,
and
'eater than segments 5 arid 6 by at least a factor of 10 (Rud.d. 1962,
Lynott 1966).
High productivity and biomass accurnU.ation due to the
uniformly wet and mild climate of the coastal Picea sitchensis zone
(Franklin and Dyrness 1973) sustain large numbers of invertebrates and
microorganisms that feed on this vegetetive biomass and its remains
(Ricklefs 1973).
A more moist and less extreme climate and preferred
foods in abundance mes segment 1 more suitable for insectivores than
the other segments.
There were no significant differences in abundance
of insectivores and vagnant shrews between
segments 2 and 3-
This
was not surprising because vegetation and, climate are so similar in
segments 2 and. 3 arid many of the same types of habitat were saaDled in
both segments.
Insectivore and. vagmant shrew mean bA values in segments
4, 5 and. 6 were significantly lower than segments 1, 2 and. 3.
d.i±'ferenc
is
rir.cially attributed to the dri3r
habitats with rich vegetative
the eastern segments.
1 imate an
This
ack c'
cund cover and deep, moist litter in
The vagmant shrew, according to Burt and.
4.
Grossenheider (196Lt.) and Hall and Kelson (1959), occurs in segments 5
and. 6, 'but apparently in extremely low densities or in areas not sampled
during this study.
Voles were captured in all segments except 5.
significantly
'eater vole abund.ance than segments 5 and. 6.
dance decreased front west to east.
west to east moisture
dance.
Segment 1 had
'ad,ient
as
Vole abun-
This decrease corresponded with the
did the decrease in insectivore abun-
Heavy precipitation and long
owing seasons in western segments
of the study area (Ruciä. 1962) produce more vegetative bioniass throughout
the year that supports a larger nuzirber of voles than eastern segments.
The higher vole abundance in the west may also be related to greater
cover provided by the dense vegetation.
Zimmerman (1965), Batzli (1968),
and. Shure (1970) found Microtus abundance greater in areas with higher
density of herbaceous cover.
Maser and Storm (1970) and Goez-tz (1959,
19614) found generally that most voles (Microtus spp.) prefer heavy
ground cover of mixed grasses, sedges, and forbe in rparian or moist
areas.
Although geographic differences in abundance were evident for mice,
insectivores, and voles, total mammal abundance was not statistically
different among segments.
It was probably coincidental that indices of
total mammals were similar in all segments (Table 9), whereas voles and,
insectivores decreased and. mice tncreased from west to east, because
capture probabilities are not equal for these different groups of
species.
It is interesting to note, however, the apparently related changes
that occurred across this ecological gradient.
In segment 1, relative
to the other segments, habitat disturbance was low, and climate was
less extreme and variable.
Specialists such as insectivores and herb-
ivores (voles) were more abundant, and the omnivorous deer mouse, a
generalist and early colonizer, was less abundant.
Further eastward.
along the Columbia River, habitat disturbance increased, and, climate
became more extreme and variable.
mouse Lncreased.
Specialists decreased, and the deer
In segment 5, habitat disturbance appeared gm'eatest,
specialists declined, and deer mice were most abundant.
than deer mice increased in segment 6.
Mice other
Granivorous specialists such as
the Great Basin pocket mouse, Ord's kangaroo rat, and western harvest
mouse have adapted to this more severe environment (Odum 1971., Ingles
1.965).
Deer mice decreased in abundance possibly due to the lack of
preferred habitat and competition with specialists and other generalists.
Numerous species, whose ranges included the general area of the
study according to various authors, were riot recorded during this study
(Table 1).
These species may not have been found for several of the
following reazons
(1) sampling methods were not intensive enough to
capture the more elusive, rare, or low density species;
(2) certain
species do not occur at low elevations or in riparian areas of the Caluinbia River;
(L.)
(3) some species may inhabit areas or habitats not sampled;
some possibly no longer occur in the study area;
never have been in the study area.
or (5) some may
Present distribution and occurrence
of small niamzaals along the Columbia R±ver, however, are not drastically
different than when Bailey (1.936) did bis survey and Hall arid Kelson
(1.959) compiled their information.
46
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1962.
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Range ecension of the Beechey
our4 squirrel.
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Army
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of
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1948.
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1964.
23lpp.
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Dice, L. R.
1931.
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2(3) :119-130.
1941.
Wildi. Manage.
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J.
J. Wildl. Manage.
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J.
5(4)398-)4.07.
Etcher, G. J.
1968.
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26pp.
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Goertz, J. W.
1959.
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and Microtus montanus (Peale) in Benton County, Oregon. M.S.
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1964.
Habitats of three Oregon voles.
Ecolo
45(4):846-
848.
Gordon, K. 1966. Mammals and the influence of the Columbia River Gorge
on their distribution. Northwest Sci. 40(4):142-146.
Hall, E. R., and K. R. Kelson.
1959.
Mammals of North America.
Ronald Press Cc., New York. lOSJpp.
The
Hansson, L.
1967.
Index line catches as a basis of population studies
on small mammals. Oiicos 1a(2):261-276.
Hayne, D. W.
1949.
Two methods for estimating population from trapping
J.
Mammal.
30(Ll.):399_411.
records.
Hedlund, J. D., ar4 W. H. Rickard.
1976.
Small mammal populations near
the Trojan Nuclear Power Stat ion, Oregon. Northwest Sci. 50(3):172177.
Hitchcock, C. L., and A. Cronquist
1973.
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730pp.
Ingles, L. C.
1965.
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Stanford Univ.
1970. The f±sh and wild.life resources of
the lower Columbia River area. Special Rep. Oregon State Caine
Comm., Portland. l7pp. Typescript.
Ives, F., and W. Saltznian.
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change to avian populations, particularly waterfowl. M.S. Thesis.
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1975. Revised
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Larrison, E. J. 1970.
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1970. Rare ntatnznals of Washington.
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162pp.
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,J. 3. Saunders Co., Phil-
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APPTDICES
TABLE A.
Sampling
Area No.
1
Intensive sampling areas established in the Columbia River study area, 1974-1975.
Segment
1
Shore
Habitat
Oregon
Beachgrass
Location
RN 5, E.
H. 11 W.
RN 7, N.W.
R. 10 W.
RN 7, N.W.
H. 10 W.
,
Elevation
S. 35, T. 8 N.,
Near sea level
2
1
Oregon
Tidal marsh
3
1
Oregon
Tidal marsh
4
1
Oregon
Alder
RM7,W.,S.6,T.8N.,
5
1
Washington
Beachgrass
R. 10 W.
Ft. Canby State Park
6
1
Washington
Alder
Ft. Canby State Park
7
1
Washington
Tidal marsh
Ft. Canby State Park
1
2
Oregon
Tidal marsh
RN 21, NE.
Oregon
, 3. 6, T.. 8 N.,
Intertidal
S. 6, T. 8 N.,
,
Intertidal
Near sea level
Near sea level
Near sea level
Intertidal
3
2
Oregon
4
2
Oregon
Tidal shrub
willow
Tidal Sitka
spruce
Cottonwood
5
2
Oregon
Willow
S. 20 & S.W.
S. 16, T. 8 N., R. 8 W.
RM 25, S.E.
S. 12, T. 8 N.,
H. 8 W.
RN 26, N.E. *, S. 18, P. 8 N.,
H. 7 W.
RN 65, N.E.
S. 7, T. 7 N.,
H. 2 W.
RN 71, S.E.
S. 26, T. 7 N.,
6
2
Oregon
Reed canarygrass
RN 75, E. 4, S. 13, T. 6 N.,
7
2
Oregon
Cottonwood/willow
RM 7)4, N.W.
Washington
Tidal marsh
RN 23, W. 4, S. 4, P. 9 N.,
H. 8 W.
2
2
,
,
Intertidal
4.6-8.2 m
,
1.5-3m
R.2W.
>4.6m
,
S. 12, T. 6 N.,
R.2W.
2.
Intertidal
,
R.2W.
8
Intertidal
,
13-4.6m
Intertidal
TABLE A.
Sampling
Area No.
Continued.
Segment
2
Shore
Washington
Habitat
15
2
Island
Tidal Sitka
spruce
Tidal marsh
16
2
Island
Tidal marsh
9
17
2
Island
18
2
Island
19
2
Island
Tidal shrub
willow
Tidal Sitka
spruce
Cottonwood
20
2
Island
Cottonwood/willow
22
2
Island
Reed canarygrass
3
Oregon
Cottonwood
3
Oregon
Cottonwood/willow
3
3
Oregon
4
3
Oregon
Ash/willow/cottonwood
Reed canarygrass
5
3
Oregon
Willow
6
3
Oregon
Shrub willow
7
3
Oregon
Ash/willow/cottonwood
1
2
Location
RN 37, N.W.
Elevation
S. 35, P. 9 N.,
,
IL 6 W.
Intertidal
RN 30, W. -, S. 24, T. 9 N,
R. 7 W.
RN 32, N.W.
S. 19, P. 9 N.,
H. 6 W.
RN 32, N. *, S. 19, T. 9 N.,
R. 6 W.
RN 36, S.W.
S. 24, T. 9 N.,
Intertidal
,
Intertidal
Intertidal
,
IL. 6 W.
RM 7Li, S.W.
H. 1
RN 75,
H. I
RN 75,
R. 1
Intertidal
,
S. 7, P. 6 N.,
,
S. 7, T. 6 N.,
,
S. 18, P. 6 N.,
3-4.6
W.
S.W.
W.
N.W.
W.
in
3-6.1 m
1.5-.3 m
RN 89, Ii.
5. 22, P. 4 N.,
R. 1 W.
RN 91, N.E.
S. 34, T. 4 N.,
R. 1 W.
RN 91, N.
S. 34, T. 4 N.,
R. 1 W.
RM 97, N.W.
S. 26, P. 3 N.,
R. 1 W.
RN 130, S.W. -, S. 21, T. 1 N.,
R. 1 E.
RN 130, S. -, S. 20, P. 1 N.,
E.
H.
Rm 130, N.E.
S. 29, T. 1 N.,
,
4-5.2 m
,
3-4.6 m
,
3-4.6 m
,
1.
,
H. 5 E.
4.6-6.1
in
TABLE A.
Sampling
Area No.
Continued.
Segment
Shore
Habitat
Location
Elevation
3
Washington
Cottonwood
3
Washington
Cottonwood/willow
11
3
Washington
12
3
Washington
Ash/willow/cottonwood
Willow
13
3
Washington
Shrub willow
RN 120, N. fr, S. 14, T. 1 N.,
H. 3 E.
RN 123, S.E.
S. 17, T. 1 N.,
H. 4 E.
RN 91, N.W.
S. 35, T. 4 N.,
H. 1 W.
RN 90, SW.
S. 26, T. L1' N.,
H. 1 w.
RN 123, S.E.
3. 17, T. 1 N..,
14
3
Washington
Reed canarygrass
RN 123, S.E.
9
10
,
Island
Cottonwood
16
3
Island
Willow
17
3
Island
Shrub willow
3
Island
Reed canarygrass
18
3
Island
Cottonwood/willow
5.8-6.1
-i-,
S.
RN 125, S.
6.8m
fr,
R. 4 E.
RM 125, N.E.
R. 4 E.
RN 125, N.E.
H. 4 E.
S. 21, T. 1 N.,
6.7-7.3 in
,
S. 21,
T.
,
S. 21,
T. 1 N.,
1 N.,
6.1-6.7 rn
5.5-6.1 m
RN 126, W. fr, S. 22, T.
RN 124,
4
Oregon
Willow
4
Oregon
Willow
3
4
Oregon
Douglas fir/maple
4
4
Oregon
Oak/Ponderosa
pine
2
in
17, T. 1 N.,
1
N.,
N.tJ.
6.4-7.9 m
,
S. 20,
T. 1 N.,
H. 4 E.
1
3-4.3 m
,
H. 4 E.
19
3-4.6 in
,
R.4E.
3
7.3-9.1 m
,
R. 4 E.
15
7.6-9.1 m
RN 161, N.E.
R. 9 E.
RN 161, N.W.
B. 9 E.
RN 161, S.W.
H. 9 E.
RN 177, S.W.
H. 12 E.
5.5-7.6 m
,
S. 34,
T. 3 N.,
23.8-23.9 in
,
S.
35, T.
3 N.,
S.
35, P.
3 N.,
23.5-24.1 m
45.7-122 m
,
S. 32, T. 3 N.,
27.4-61 ii
A)
TABLE A.
Sampling
Area No.
Continued.
Segment
Habitat
Shore
5
ii
Oregon
Oak
6
4
Oregon
Grassland
7
4
Oregon
Shrub willow
8
Li-
Oregon
Rock rip-rap
10
Li-
Washington
Oak
11
Li-
Washington
Douglas fir/maple
12
Ll
Washington
Grassland
13
4
Washington
14
Li-
Washington
Oak/Ponderosa
pine
Willow
15
4
Washington
Willow
16
4
Washington
Rock rip-rap
1
2
3
4
5
Oregon
5
Oregon
5
Oregon
5
Oregon
Rabbitbrush
Rockcliff/grassland
Shrub willow
Willow
Location
Elevat:lon
RN 178, S.W.
S. 33, T. 3N.,
R. 12 E.
RN 178, SW.
S. 33, P. 3 N.,
R. 12 E.
RN 179, S.E.
S. 33, P. 3 N.,
R. 12 E.
RN 180, S.W.
S. 34, T. 3 N.,
E.
R. 12
RN 162, N. --, S. 26, T. 3 N.,
R. 9 E.
RN 162, N.W.
S. 26, T. 3 N,
R. 9 E.
S. 32, T. 3 N.,
RN 178, N.
,
H. 12 E.
RN 176, S.W. +, S. 25, P. 3 N.,
R. 11 E.
5. 33, P. 3 N.,
RN 179, N.
H. 12 E.
5. 7, T. 2 N.,
RN 183, N.W.
R. 13 E.
RN 177, N.
S. 36, P. 3 N.,
R. 11 E.
,
30.5-61
in
,
67.l-73.2m
,
23.2-25 m
,
28.9
in
at top
24.4-30.5 in
,
48.8-122
in
36.6-61 in
36.6-97.6 m
,
22.9-27.4 m
,
23.8-25.3 m
,
RN 198,
R. 14
RN 203,
H. 15
RM 210,
R. 16
RN 211,
R. 16
N.E.
,
S. 24,
T. 2 N.,
122 m
E.
N.W.
E.
S.E.
,
S. 22, P. 2 N..,
79.3-91.5
-,
S.
2,
-,
S.
1,
P. 2 N.,
E.
S.W.
E.
30.5 m at top
--61 rn
T. 2 N.,
'61 m
in
TABLE A.
Continued.
Sam p11 ng
Area No.
Segment
Shore
Habitat
5
Oregon
Rock rip-rap
5
Washington
Rock rip-rap
8
5
Washington
Rabbitbrush
9
5
Washington
Rockcliff/grassland
6
7
1
6
Oregon
Talus
2
6
Oregon
3
6
Oregon
Hockcliff/grassland
Sagebrush
4
6
Oregon
Bitterbrush
5
6
Oregon
Rabbitbrush
6
6
Oregon
Grassland
7
6
Oregon
Cottonwood/willow
8
6
Oregon
Ivlarsh
9
6
Oregon
Russian Olive
11
12
6
6
Washington
Washington
Rock rip-rap
Bitterhrush
Location
Elevat :1 on
RN 208, N. *, S. 9, T. 2 N.,
H. 16 E.
RN 207, N.W.
S. 7, T. 2 N.,
R. 16 E.
RN 210, E.
S. 35, P. 3 N.,
R. 16 E.
RN 211, N.W.
S. 36, T. 3 N.,
R. 16 E.
-61 m
,
.-61 m
,
51.8-59.5
in
,
RN 222,
H. 18
RN 227,
H. 19
RN 227,
R. 19
RN 273,
R. 26
RN 274,
R. 26
RN 276,
H. 26
RN 275,
R. 26
RN 276,
R. 26
RN 279,
R. 26
RN 283,
68.6-106.7 m
N.W. j, S. 21, T. 3 N.,,
E.
N.W. -, S. 6, P. 3 N.,
122-182.9 m
E.
182.9-243.9
N.E.
,
5.
6, T. 3 N.,
91.5-137.2
E.
LW.
-j,
S.
31, T. 5 N.,
E.
N.W.
,
S.
in
88.4-91.5
in
85.4-88.4
in
31, T. 5 N.,
E.
N. *, S. 20, T. 5 N.,
83.8-86.9 in
E.
S.E.
E.
N.E.
E.
N.W.
E.
N. --,
H. 27 E.
RM 281, N.E.
R.26 E.
19, T. 5 N.,
,
S.
,
S. 29, T.
80.8-82.3 m
5 N.,
80.2-81.7
,
in
S. 22, P. 5 N.,
85.4 in
S. 17, T. 5 N.,
83.8
,
5.
in
13, T. 5 N.,
88.4-89.9 in
TABLE A.
Continued.
Sampling
Area No.
Segment
13
6
Shore
Washington
Habitat
Rabbitbrush
14
6
Washington
Grassland
15
6
Washington.
Marsh
16
6
Washington
Talus
17
6
Washington
18
6
Washington
Rockcliff/grassland
Sagebrush
19
6
Washington
Cottonwood/willow
Location
RN 281, N.E.
R. 26
RN 281,
R. 26
RM 280,
R. 26
RN 230,
R. 19
RN 230,
R. 19
RN 229,
R. 19
RN 280,
H. 26
13, P.
5 N.,
12, T.
5 N.,
,
11, P.
5 IL,
,
34, T.
3 N.,
,
S.
E.
S.E. -, S.
E.
N.E.
S.
E.
N.W.
S.
E.
N.
E.
S.E.
,
Elevation
S.
85.4-88.4
82.3-85.4 m
80.2-81.7 m
85.4-122
in
33, P. 3 N.,
122-182.9 n
,
S. 20, P.
3 IL,
S. 14, T.
5 N.,
E.
N.W.
E.
in
85.4-97.6 m
fr,
80.8-82.3 m
'FABLE B.
Mean index of abundance values (captures per 100 trap-nights) in small mammal intensive
sampi ing areas inventoried during fall 1974
and spring 1975 in segment 1 of the Columbia River study area.'
Intensive Sampling Area / Season
Oregon
Bcachgrass
Species or Group
Vagrant shrew
Dusky shrew
Pacific water shrew
Trowbridge's shrew
Shrew-mole
Coast mole
S.A. I
1b Sp
(96) (96)
10.6
8.3
Washington
Beachgrass
S.A. 5
F
S.A.
3
F
Sp
(60) (60)
Sp
(60) (60)
13.0
20.4
14.4
6.1
1. 1
16.7
1.9
19.9
Washington
Tidal Marsh
S.A. 7
F
Sp
(78) (78)
5.5
10.6
Oregon
Alder
S.A. 4
F
(78)
4.2
Sp
(96)
1.1
Washington
Alder
S.A. 6
F
Sp
(96) (96)
8.7
d
47
e
0.9
Snowshoe hare
Townsend' a chipmunk
California ground squirrel
Douglas' squl rrel
Townsend's vole
Long-tailed vole
Creeping vole
Pacific jumping mouse
Short-tailed weasel
Long-tailed weasel
Total Mammals
(TOMA)
TOMA - Deer Mouse + Vagrant Shrew
Insectivores
Insectivores - Vagrant Shrew
Mice
Mice - Deer Mouse
Voles
F
Orcgoii
Tidal Harsh
Sp
(96) (96)
e
1
è
1
Brush rabbi t
I)eer mouse
Oregon
Tidal Marsh
S.A. 2
e
e
1.9
3.3
1.1
2.0
1.1
6.7
2.2
2.2
2.2
0
e
f
f
2.2
5.9
1.
e
1.1
5.4
1.9
4.2
3.7
8.9
1.4
1.1
11.5
1.1
d
10.6
2.0
d
6.5
3.3
3.7
15.3
8.8
13.0
13.7
0.9
11.5
0.9
2.2
15.3
1.1
9.4
1.1
5.9
21.7
7.6
14.1
14.8
3.3
6.1
1.1
1.1
5.4
6.5
3.3
1.9
27.8
7.4
22.2
1.9
3.7
LI
1.4
i .
1.1
1.9
1.9
39.4
22.7
18.5
1.9
26.8
12.5
14.4
34.7
13.0
19.9
12.2
2.5
5.5
20.9
11.1
1.4
10.6
5.8
8.9
4.7
1.9
1.9
8.8
1.9
5.5
1.4
1.1
8.9
1.1
19.0
13.0
20.4
7.8
8.9
7.8
11.5
13.0
3.1
11.9
3.1
1.1
1.1
1.4
aintejisive sampling areas were sampled 2, 3 or 4 consecutive nights in fall 1974 and 3 or 4
consecutive nights in spring 1975, but only the
first 2 nights were used to calculate captures per 100 trap-nights.
fall 1974; Sp= spring 1975.
CN(nnl)el.S in parentheses equal trap-nights (luring first 2 nights.
1Cap1ured after second night.
captured, but was observed and/or identified by sign in saml)I ing area.
Captured in non-standardized traps only.
31.3
14.1
17.6
10.9
11.7
2.0
TADLE C.
Small mammal captures per 100 trap-nights and species diversity index values by trap station type in habitats inventoried in segment
1 of the Columbia River study area.a
Uahitat' / Trap Station 'fype
Tidal Marsh (396)
Beachgrass (384)C
Species or Group
1
2
Dusky shrew
10.0
0.8
Shrew-mole
0.8
11.8
Vagrant shrew
Pacific water sitrew
Trowbridge's shrew
Coast mole
3
6.7
12.8
16.7
3
X
1
2
3
X
12.5
14.0
0.8
0.3
0.7
0.7
0.8
0.3
5.3
4.4
0.9
2.6
0.9
9.6
0.9
0.9
3.5
2.6
5.2
2.0
0.6
3.0
1.2
e
d
f
e
3.5
4.2
3.3
3.7
1.9
2.5
1.7
Long-tailed vole
Creeping vole
4.2
0.8
2.9
0.8
0.7
2.5
4.2
2.5
3.2
2.5
0.8
1.7
0.8
27.5
6.7
13.3
6.3
0.5
0.6
0.3
26.0
Pacific jumping mouse
Short-tailed weasel
I,ong-tailed weasel
Total majiunats
(TOMA)
f4A - deer mouse + vagrant shrew
Insectivores
Insectivores - vagrant shrew
Mice
Mice
Voles
-
0.2
0.7
Deer mouse
Townsend's vole
2.9
e
Snowshoe hare
Townsend's chipmunk
California ground squirrel
Douglas' squirrel
9.5
0.3
2
0.3
0.2
e
0.7
Drush rabbit
1
Alder (366)
16.7
1.4
12.5
0.7
3.5
18.3
4.2
0.7
2.5
deer mouse
4.2
11.7
1.7
3.3
10.3
17.9
3.2
12.8
3.3
0.8
3.7
1.9
4.2
2.5
1.03
3.2
0.79
14.2
4.2
6.7
16.4
0.8
16.7
32.5
17.5
14.2
1.7
5.0
0.8
3.3
3.3
0.8
15.0
9.1
14.6
5.8
0.7
3.5
0.9
6.3
0.5
d
0.3
0.9
g
11.6
5.1
0.6
4.3
3.6
3.4
5.8
7.2
1.15
0.7
0.5
9.6
24.6
9.6
14.0
21.9
8.8
17.5
10.5
7.9
3.5
8.8
0.9
0.9
19.4
7.8
11.9
6.8
6.6
0.3
0.5
1.52
1.21
0.84
1.05
1.29
1.36
1.37
1.61
1.59
Species diversity index
aijitensive sampling areas were sampled 2, 3 or 4 consecutive nights in fall 1914 and 3 or 4 consecutive nights in spring 1975, but only the
first 2 nights were used to calculate captures per 100 trap-nights.
bintetisive sampling areas of similar habitat combined; seasons combined.
CNumhers in parentheses equal trap-ni guts during first 2 iiights.
dCaptUrcd after second night.
eNO captured, but was observed and/or identified by sign in this habitat.
Captured in non-standardized traps only.
recorded in intensive sampling areas, but was observed in this habitat.
FABIJ
U.
Mean index of abundance values (captures per 100 trap-nights) n small mammal intensive sampling areas inventoried during fall 1974
and spilug 1975 in Segment 2 ot the Columbia River study
Intensive Sampling Area / Season
Oregon
Species or Cintip
Vagrant shrew
Dusky shrew
Oregon
Tidal
Tidal
Marsh
S.A. 1-Ilk
S.A. 1-Ut)
Tidal
Marsh
F
(60)L
Sp
(6(1)
(60)
(60)
5.6
18.5
1.4
1.9
F
Island
Tidal
Washington
Sp
Pacific water shrew
Jrowbridge's shrew
Marsh
Marsh
S.A. 8
S.A. 16
F
F
(96)(66)
Oregon
Island
Oregon
Washington Island
Tidal Shrub Tidal Shrub Tidal Sitka Tidal Sltka Tidal Sitka
Spruce
Willow
Wi 1 low
S.A. 2
S.A. 17
F
Sp
(60)
(18)
0.9
F
S.A.
F
Spruce
S.A. 9
(78)
(51)
2.5
6.7
20.8
8.3
23.3
14.9
2.5
6.7
20.8
8.3
(96)
(60)
(60)
3.2
3.7
3.3
1.9
e
e
2.2
Spruce
3
Sp
P
S.A. 18
F
Townsend's mole
llrush rabbit
Eastern cottontati
Townsend's chtpiiiunk
California ground squirrel
Northern flying squirrel
Ileer mouse
e
a
1.4
Townsend's vole
Long-tailed vole
Creeping vole
Norway rat
Pacific jumping mouse
Insectivores
Insectivores
Mice
Mice
Voles
-
Vagrant Shrew
Deer Mouse
7.4
10.2
7.2
1.9
d
19.9
16.2
e
d
26.8
3.3
7.0
3.3
19.9
18.0
1.9
1.9
1.9
16.2
d
1.4
1.9
long-tailed weasel
'lutal Mammals (TO14A)
lOMA - Deer Mouse + Vagrant Shrew
5.6
8.3
1.4
5.6
1.4
25.9
1.9
8.8
18.5
1.4
7.4
1.9
12.0
10.4
2.2
7.4
1.9
3.1
10.2
2.2
7.2
1.9
3.2
3.2
1.9
sampling areas were Sampled 2, 3 or 4 consecutive nights in fall 1974 and 3 or 4 consecutive nights in spring 1975, hut only the first
2 nights were used to calculate captures per IOU trap-nights.
bNot
all intensive sampling areas were sampl ed during the spring sampling period; F= f1 1 1974; Sp= spring 1975.
Nuiat)ers in parentheses equal trap-nights during first 2 nights.
daptt*tej after second night.
£Not captured, but was observed und/or identified
by sign in sampling area.
Captured in non- standardi zed traps only.
lABLE I).
Coot inued.
intensive Sampling Arca / seasonb
Oregon
Island
Oregon
Cottonwood
Cottonwood
Willow
S.A. 4
S.A. 19
Sp
F
Species or group
(96)
Vagrant shrew
Dusky shrew
S.A. 7
SA. 5
Sp
F
F
Oregon
Cottonwood/
Willow
Sp
F
Island
Oregon
Cottonwood/
Reed
Willow
S.A. 20
F
island
Reed
Canarygrass
S.A. 6
Canarygrass
S.A. 22
F
Sp
F
(96)
(96)
(96)
(96)
(96)
(96)
(96)
(96)
(96)
(78)
2.0
9.4
5.0
Li
4.1
1.1
3.0
7.0
14.1
5.3
e
C
10.7
1.1
1.1
O9
3.3
15.2
5.2
8.0
1.1
16.3
2.2
5.3
3.3
14.1
5.3
Pacific water shrew
Trowbridge' s shrew
Townsetui' a mole
Brush rabbit
Eastern cottontail
Townsend's chipmunk
Call forn i a ground qui rre 1
Northern flying squirrel
Deer mouse
Townsend's vole
-
C
e
(TOMA)
l)eer Monad + Vagrant Shrew
1.1
1.1
Mice
Voles
2.0
d
3.2
20.4
31.1
0.9
d
2.2
1.9
1.1
e
2.2
1. 1
Insectivores
insectivores - Vagrant Shrew
Nice
e
C
Creeping vole
Norway rat
Pacific j umping mouse
Long-tailed weasel
TOMA -
e
e
Long-tailed vole
Total Mammals
t
7.0
3.0
2.0
1.1
2.0
1.1
3.0
Denr Mouse
9.4
8.2
22.4
35.2
0.9
9.4
5.0
1.1
4.1
1.1
3.0
7.0
3.2
20.4
31.1
10.7
1.1
0.9
3.3
1.1
0.9
2.2
aintensive sampling areas were sampled 2, 3 or 4 consecutive nights in fall 1974 and 3 or 4 consecutive nights in spring 1975, but only the
first 2 nights were used to calculate captures per 100 trap-n:ights.
liNot all intensive sampling areas were sampled during the spring sampling period; F= fall 1974; Sp spring 1975.
CNt1IIi)ers in parentheses equal trap-nights during first 2 nights.
dCapt1red after second night.
captured, but was observed and/or identified by sign in sasipling area.
tCapturcd in non-standardized traps only.
eNO
TABLE E.
Small mammal captures per 100 trap-qights and species diversity index values by trap station type in habitats inventoried in segment
2 of the Columbia River study area.'
Habitat b / irap Station type
Tidal Marsh (402)C
Species or Group
Vagrant shrew
Dusky shrew
Tidal Shrub Willow (174)
1
2
3
X
1
6.4
1.6
5.0
4.3
1.5
0.8
0.8
0.5
Pacific water shrew
Trowbridge 's shrew
Townsend's mole
2
Tidal Sitka Spruce (249)
3
X
1
2
3
X
3.7
1.7
1.0
1.0
1.3
6.7
2.7
3.0
1.2
e
e
e
Brush rabbit
Eastern cottontail
Townsend's chipmunk
e
California ground squirrel
Northern flying squirrel
Deer mouse
Townsend's vole
d
3.8
5.6
6.7
5.4
1.9
0.6
16.2
14.7
20.0
17.0
Long-tailed vole
Creeping vole
Norway rat
Pacific jumping mouse
Long-tailed weasel
Total mammals (TOMA)
TOP4A - dcci mouse + vagrant shrew
Insectivores
Insectivores - vagrant shrew
Mice
Mice - dcci- mouse
0.6
10.9
0.6
6.4
0.2
0.3
0.8
8.7
1.6
2.4
3.8
0.8
6.3
0.8
0.84
1.03
12.5
10.7
0.8
5.8
0.8
6.7
1.0
4.9
0.5
5.6
0.3
0.88
0.92
Voles
Species diversity index
d
e
1.5
5.6
2.4
1.5
3.7
1.7
1.9
0.6
0.64
0.21
18.2
1.0
16.0
2.0
1.0
1.3
16.2
14.7
0.42
0.28
29.3
2.7
9.3
2.7
20.0
0.82
21.2
1.2
4.2
1.2
17.0
0.51
aijitensive sampling areas were sampled 2, 3 or 4 consecutive nights in fall 1974 and 3 or 4 consecutive nights in spring 1975, but only the
first 2 nights were used to calculate captures per 100 trap-nights.
bintensive sampling areas of similar habitat combined; seasons combined.
CNumt,ers in parentheses equal trap-nights during first 2 nights.
dCapttlred after second night.
eNO
captured, but was observed and/or identified by sign in this habitat.
Captured in iion-standardized traps only.
recorded in intensive sampling areas, but was observed in this habitat.
TABLE Ii.
Continued.
Iiabitat' / Trap Station Type
(288)C
Cottonwood
Species or Group
Vagrant shrew
Willow (192)
Cottonwood / Willow (288)
Reed Canarygrass (270)
1
2
3
1
1
2
3
I
1
2
3
X
1
2
3.7
4.4
3.3
3.8
4.2
3.3
1.7
3.1
3.7
2.2
2.2
2.7
6.9
9.5
3
10.7
9.0
2.4
0.3
0.8
13.1
2.4
10.7
10.1
0.8
9.0
I)usky shrew
Pacific water shrew
Trowbridge's shrew
Townsend's mole
Brush rabbit
Eastern cottontail
'rownsend's chipmunk
California ground squirrel
Northern flying squirrel
Deer mouse
Townsend's vole
Long-tailed vole
Creeping vole
Norway rat
Pacific jumping mouse
Long-tailed weasel
Total mammals
(TOMA)
TOMA - deer mouse + vagrant shrew
Insectivores
Insectivores - vagrant shrew
Mice
Mice
deer mouse
Voles
Species diversity index
f
e
e
e
C
g
0.9
2.2
1.1
1.9
1.1
1.0
0.4
0.6
0.4
e
g
15.3
1.4
10.0
10.0
11.8
0.5
18.5
11.1
1.1
13.3
3.3
14.3
1.5
1.0
e
6.5
1.0
3.7
7.8
2.2
3.3
6.2
20.8
1.4
3.8
1.4
4.2
3.3
0.9
2.2
1.0
15.3
10.0
1.9
0.95
2.2
1.27
1.4
1.4
0.74
0.73
4.4
4.4
13.3
22.2
1.7
15.3
0.5
3.1
3.7
10.0
11.8
18.5
11.7
0.56
0.41
0.5
0.57
18.5
1.5
2.7
7.8
9.5
2.2
18.9
3.3
2.2
6.9
9.5
11.1
13.3
14.3
1.0
1.1
3.3
1.5
0.68
0.80
0.64
14.4
1.1
0.45
0.37
0.3
2.4
0.48
0.8
0.28
aintensive sampling areas were sampled 2, 3 or 4 consecutive nights in fall 1974 and 3 or 4 consecutive nights in spring 1975, but only the
first 2 nights were used to calculate captures per 100 trap-nights.
bintensive sampling areas of similar habitat combined; seasons combined.
CNt)ers in parentheses equal trap-nights during first 2 nights.
dCaptured after second night.
eNO
captured, but was observed and/or identified by sign in this habitat.
1'Captured in non-standardized traps wily.
recorded in intensive sampling areas, but was observed in this habitat.
Wan index of abundance values (captures per 100 trap-nights) in sisal I mammal intensive sampling areas iliventori ed during fall 1974
and spring 1975 in segment 3 of the Columbia River study area.a
TABLE F.
Intensive Sampling Area
Oregon
Cottonwood
Washington
Cottonwood
Is land
Oregon
Cottonwood Cottonwood!
S.A. 1
Species or (roup
Vagrant shrew
Dusky shrew
(72)
F
Sp
S.A. 10
Sp
F
Deer mouse
(TOMA)
20.8
flA - Deer Mouse + Vagrant Shrew
Insectivores
2.8
Insectivores Vagrant Shrew
Mice
Voles
S.A. 7
S.A. 11
Sp
(78)
(96)
(96)
(96)
(96)
(96)
3.2
17.6
5.6
3.0
5.6
0.9
7.8
4.4
9.3
3.2
d
d
e
18.0
F
(96)
Willow!
F
(96)
8.7
1. 1
e
e
C
d
12.5
1.4
38.0
13.9
1.4
42.2
12.5
1.4
12.2
1.1
2.0
29.8
1.1
3.2
17.6
38.0
1.1
12.2
7.6
2.0
5.6
2.1)
"Intensive sampling areas were sampled 2, 3 or 4 consecutive nights in
10.8
1.1
21.4
22.0
17.8
5.0
1.1
14.8
1.1
31.9
5.0
5.6
24.1
1.1
0.9
3.3
2.8
31.7
6.1
7.8
21.4
22.0
1.1
17.8
6.1
3.0
10.8
1.1
fall
5.0
1974 and 3 or
first 2 nights were used to calculate captures per 100 trap-nights.
bNot all intensive sampling areas were sampled
during the spring sampling period; F=
Nuinher iii parentheses equal trap-nights during first 2 nights.
dCaptured in non-standardized traps only.
CNot
S.A. 3
F
(96)
C
Long-tailed vole
Total Mammals
Cottonwood
d
18.0
Townsend's vole
Willow!
Cottonwood
S.A. 19
F
Washington
Ash!
Willow/
(96)
Brush rabbi
Eastern cottontail
Northern flying squirrel
Ash!
(96)
d
d
S :401 C
F
Oregon
Ash/
Cottonwood
Willow
Willow
Oregon
(96)
2.8
Shrew-mole
1 ownsend'
(72)
Sp
F
S.A. 2
S.A. 15
S.A. 9
Sp
Scasont
Washington
Is land
Cottonwood/ Cottonwood/
Willow
F
/
captured, but was observed and/or identi fled
by
sign in sampling area.
fall
37.6
0.9
2.0
15.6
4.8
38.3
2.0
43.0
0.9
4.4
11.3
18.7
5.9
49.1
9.3
3.2
37.6
2.0
15.6
0.9
LI
1.1
LI
4.8
20
8.7
38.3
2.0
4 consecutive nights in spring 1975, but only tile
1974; Sp= spring 1975.
TABLE F.
Continued.
Intensive Sampling Area
Oregon
Washington
Island
Reed
Reed
Reed
Canarygrass Canarygrass
SA. 4
S.A. 14
Washington
Oregon
Willow
Canarygrass
S.A. 18
Willow
/
casonb
Island
Oregon
Shrub
Willow
Willow
S.A. 5
S.A. 12
S.A. 6
S.A. 16
Wasliiiigton
Island
Shrub
Shrub
Willow
S.A. 13
Willow
S.A. 17
F
Sj)
Species or Group
(96)
(96)
(96)
(96)
(96)
(96)
(96)
(96)
(78)
(78)
(78)
Vagrant shrew
Dusky shrew
1.1
1.1
28.3
4.1
1.1
4.3
0.9
3.0
1.4
2.8
1.4
F
F
Sp
F
F
F
Sp
Brush rat'bit
Eastern cottontail
Northern flying squirrel
Deer mouse
Townsend's vole
e
e
lie8
5.2
7.2
18.9
40.7
7.2
28.3
[,ong-tai led vole
-
(P3MA)
Deer Mouse
+
1.1
Vagrant Shrew
Insectivores
Insect ivores - Vagrant Shrew
Mice
Voles
(78)
1.4
d
Townsend's iiiole
TOMA
F
Sp
(78)
1.1
Shrew-mole
Total llaiiimals
F
1.1
1.1
17.8
5.2
7.2
e
e
20.5
2.2
2.0
6.3
23.7
2.0
1.1
2.2
4.1
20.5
2.2
2.0
e
C
12.2
3.1
39.3
4.3
20.7
44.4
4.3
5.4
4.3
0.9
1.1
12.2
3.1
39.3
4.3
3.0
1.1
1.4
5.6
5.3
11.4
17.8
2.8
3.9
12.8
20.6
2.8
1.4
13.6
5.3
2.8
1.1
1.4
5.6
5.3
11.4
1.4
3.0
nights in fall 1974 and 3 or 4 consecutive nights in spring
first 2 nights were used to calculate captures per 100 trap-nights.
bNot all intensive sampling areas were sampled during the spring sampling period; F= fall 1974; Sp= spring 1975.
cNumbers in parentheses equal trap-nights during first 2 nights.
dapt ured in non-standardized traps on1y.
e80 captured, but was observed and/or identified by sign in sampling area.
alflteflsjve sampling areas were sampled 2, 3 or 4 consecutive
C
1.4
1975,
1.4
1.4
17.8
2.8
but only the
TABLE G.
Small mammal captures per 100 trap-nights and species diversity index values by trap station type in habitats inventoried in segment
3 of the Columbia River study area.
Ilabitat' / Trap Station Type
(432)C
Cottonwood
Species or Group
Vagrant shrow
1
2
1.3
2.9
Cottonwood / Willow (462)
X
1
2
3
X
1
2
3
X
6.2
1.7
2.8
8.3
4.3
4.2
3.3
8.3
5.3
0.8
0.3
3
14.5
Ash I Willow / Cottonwood (384)
I)usky shrew
Shrew-mole
Townsend's mole
Brush rabbit
Eastern cottontail
California ground squirrel
Gray squirrel
Northern flying squirrel
Deer mouse
Townsend's vole
Long-tailed vole
Long-tailed weasel
total mammals
(IOWA)
1O1A - deer mouse + vagrant shrew
InsectiVores
Insectivores - vagrant shrew
t4ice
d
e
e
e
f
f
d
19.2
0.6
17.4
12.3
0.7
1.4
21.2
0.6
28.3
1.3
21.0
0.7
2.9
19.2
17.4
16.3
0.9
d
20.7
1.7
1.7
30.6
25.9
14.5
23.5
0.9
6.2
12.3
16.3
f
1.4
22.0
2.2
0.6
18.1
0.7
14.2
0.8
13.3
2.1
14.6
2.8
15.2
0.5
35.4
2.1
2.8
25.7
2.8
8.3
29.0
3.4
1.7
4.3
22.9
0.7
4.2
18.3
0.8
3.3
20.7
30.6
14.6
22.0
18.1
14.2
22.5
0.8
9.2
0.8
13.3
21.2
0.8
5.6
0.3
15.2
2.8
Nice - deer mouse
'kilos
Species diversity index
0.6
0.36
0.7
0.54
1.4
0.85
0.9
0.58
3.4
0.72
2.1
0.49
2.8
0.93
2.8
0.71
0.7
0.60
0.8
0.64
0.80
0.5
0.68
ajitensive sampling areas were sampled 2, 3 or 4 consecutive nights in fall 1974 and 3 or 4 consecutive nights in spring 1975, but only the
first 2 nights were used to calculate captures per 100 trap-nights.
bintensive sampling areas of similar habitat combined; seasons combined.
CNLanbers in parentheses equal trap-nights during first 2 nights.
dCaptured in non- standardized traps only.
e0 captured, but was observed and/or identified by sign
in this habitat.
recorded in intensive sampling areas, but was observed in this habitat.
0"
TABLE C.
Continued.
llabitat' / Trap Station Type
Species or Group
Vâgant shrew
1
2
3
3.5
5.8
16.7
1
8.7
2.8
Deer mouse
Towisend's vole
Long-tailed vole
Long-tailed weasel
(TOMA)
deer mouse + vagrant shrew
Insectivores
TOMA -
Iiisectivores - vagrant shrew
-
3
1.7
2.5
1
2.3
0.3
2
3
X
1.7
2.5
1.4
d
Brush sabbt
Eastern cottontail
Californis ground squirrel
Cray squirrel
Northern flying squirrel
Mice
Mice
2
0.8
Dusky shrew
Shrew-mole
Townsend's mole
Total mammals
Shrub Willow (390)
Willow (384)
Ileed Canarygrass (384)C
deer mouse
Voles
Species diversity index
e
e
a
e
5.0
1.7
6.7
3.3
5.8
2.1
2.4
21.5
2.1
20.8
3.3
11.7
1.7
18.0
2.4
10.7
0.7
7.5
0.8
3.3
4.2
7.2
1.9
11.1
2.1
12.5
1.7
26.7
15.8
1.7
2.5
10.0
10.0
0.8
4.2
10.4
0.7
1.7
2.5
1.9
1.4
5.6
5.0
6.7
5.8
21.5
20.8
23.0
2.7
2.6
0.3
18.0
11.3
16.7
26.4
2.1
2.8
26.7
5.8
16.8
2.4
8.7
7.5
3.3
7.2
2.1
1.02
1.7
0.99
3.3
0.90
2.4
0.97
2.1
0.8
0.72
4.2
1.9
0.67
5.6
3.5
3.3
0.61
4.2
2.5
0.8
3.3
0.73
11.7
1.7
0.75
2.4
0.70
10.7
0.7
0.22
1.08
alriteiisive sampling areas were sampled 2, 3 or 4 consecutive nights in fall 1974 and 3 or 4 consecutive nights in spring 1975, but only the
first 2 nights were used to calculate captures per 100 trap-nights.
bintensive sampling areas of similar habitat combined; seasons combined.
CNumbers in parentheses equal trap-nights during first 2 nights.
dt.ptured in non-standardized traps only.
eNO captured, but was observed and/or identified by sign iii this habitat.
KNOt recorded in intensive sampling areas, but was observed in this habitat.
1ABLE H.
Mean index of abundance values (captures per 100 trap-nights) in s9ll mammal intensive sampling areas inventoried during fall
1974 and spring 1975 in segment 4 of the Columbia River study area.
Intensive Sampling Area
Oregon
Washington
Oregon
Washington
Willow
Willow
Willow
Willow
/
seusonh
Oregon
Shrub
Willow
S.A.
Sp
F
Species or Croup
(42)
Vagrant shrew
Pacific water shrew
Trowhiidge's shrew
Shrew-mole
S.A. 15
1
(42)
F
(96)
S.A.
F
(42)
2.8
2.8
e
1.9
d
Coast mole
S.A. 14
2
Sp
F
(42)
(78)
S.A. 7
F
(96)
Yellow-1,ellied marmot
California ground squirrel
2.8
2.8
1.9
4.2
d
f
luIrrel
Northern pocket gopher
We tern ha rvest lijouse
e
IUOUSO
llushy-tai led woodrat
Total tianimals (TOMA)
TOMA
fleer Mouse + Vagrant Shrew
Insectivores
Insectivores
4.4
17.6
2.8
(60)
3.3
1.9
1.4
5.5
5.5
10.2
17.6
14.8
7.4
4.4
33.3
12.9
4.6
1.9
17.6
21.3
29.6
26.9
5.6
5.6
2.8
4.3
9.2
21.3
8.7
4.3
4.6
5.5
d
1.9
d
3.1
21.3
17.2
13.4
1.4
7.4
4.3
25.5
4.2
22.2
5.1
3.3
3.3
17.2
16.7
3.3
8.8
9.2
5.5
Vagrant Shrew
Mice
Mice - I)cer Mouse
Voles
(60)
d
4.3
Long-tailed vole
Sp
F
(66)
f
Northern flying sqili rrel
Montanc vole
Townsend's vole
Maple
S.A. 11
d
Townsend's chipmunk
Deer
Sp
F
(66)
Washington
I)ouglas Fir!
1.1
e
Nuttall's cottontail
Douglas'
Oregon
Douglas Fin
Maple
S.A. 3
10.2
1.1
3.1
21.3
1.9
1.9
13.4
1.4
1.4
1.4
7.4
Intelisive sampling areas were sampled 2, 3 or 4 consecutive nights in fall 1974 and 3 or 4 consecutive nights in spring 1975, but only
the first 2 nights were used to calculate captures Ier 100 trap-nights.
bNot all intensive sampling areas were sampled during the spring sampling period; F= fall 1974;
Sp= spring 1975.
LNumbers in parentheses equal trap-nights during first 2 nights.
dNot captured, but was observed and/or identified by sign in sampling area.
eNO
captured until third night.
Capturcd in non- standardized traps oiily.
TABLE H.
Continued.
intensive Sampling Area / Season'
Oregon
Oak/
Ponderosa
Pine
S.A. 4
F
Species or Group
(96)
Sp
(96)
Vagrant shrew
Pacific water shrew
Troebridge's shrew
Shrew-mole
Coast mole
Washington
Oak!
Ponderosa
Pine
S.A. 13
F
(78)
Washington
Oak
S.A. 5
(96)
Oregon
Grassland
S.A. 10
Sp
F
(96)
S.A. 6
(42)
(42)
Washington
Grassland
Oregon
Rock
Rip-Rap
S.A. 12
Sp
F
F
(42)
Sp
F
(42)
(42)
F
S.A. 8
Sp
(96)
(96)
Washington
Rock
lip-Uap
S.A. 16
F
(96)
Sp
(96)
d
1.1
1.4
d
Nuttall 's cottontail
Townsend' a chipmunk
Yellow-bellied marmot
CalLfornla ground squtrrel
Douglas squirrel
Northern lying squirrel
Northern pocket gopher
Western harvest mouse
Deer mouse
Bushy-tailed woodrat
Montano vole
Townsend's vole
Long-tailed vole
Total Mammals
(TOMA)
TOMA - Deer Mouse + Vagrant Shrew
Insectivores
InsectLvores - Vagrant Shrew
Mice
Mice - Deer Mouse
Oregon
Oak
d
d
f
f
d
d
d
4
1.9
4.3
9.8
6.1
22.2
2.0
0
4.3
9.8
9.8
8.3
38.0
46.3
1.9
4.6
14.8
0.9
20.5
0.9
30.7
39.3
'
e
7.5
1.4
4.3
12 8
1.9
7.4
1.4
1.4
6.1
24.2
2.0
13.9
9.2
1.9
10.2
1.9
39.8
50.9
4.6
15.8
0.9
21.5
0.9
30 7
39.3
1.9
9.2
8.3
38.0
46.3
14.8
20.5
3(1.7
39.3
1.9
4.6
1.1
22.2
12.8
1.9
Voles
°lntensive sampling areas were sampled 2, 3 or 4 consecutive nights in fall 1974 and 3 or 4 consecutive nights in spring 1975, but only the
first 2 iiights were used to calculate captures per 100 trap-nights.
bNOt
all inl.cnsive sampling areas were sampled during the spring sampling period; F' fall 1974; Sp
CNIIMbers in parentheses equal trap-nights during first 2 nights.
dNot
captured, but was observed and/'or identi fled by sign in sampling area.
CNot captured until third night.
Captured in non-standardized traps only.
spring 1975.
TABLE 1.
Small mammal captures per 100 trap-nights and species diversity index values by trap station type in habitats inventoried in
segment 4 of the Columbia River study area.a
Habitat / Trap Station Type
Willow
Species or Group
1
Vagrant shrew
Pacific water shrew
Trowbridge's shrew
Shrew-mole
Coast mole
0.7
0.7
(342)c
2
3
X
1.0
1.0
O7
1.0
1.0
1.0
0.6
0.9
NuttaiPs cottontail
Snowshoe hare
Townsend's chipmunk
Yellow-bellied marmot
IJouglas Fir
Shrub Willow (96)
1
2
3
X
3.3
1.1
I
Maple (252)
1
2
3
X
2.1
1.2
1.4
1.6
d
f
0.2
0.7
2.1
1.2
1.4
1.6
d
California ground squirrel
Western gray squirrel
Douglas' squirrel
Northern flying squirrel
d
g
Northern pocket gopher
Western harvest mouse
Iieer
,liouse
Bushy-tailed woodrat
Montane vole
Townsend's vole
Long-tailed vole
(TOMA)
Total mammals
T0t'IA - deer mouse + vagrant shrew
ijisectjvores
Iiisecti vores
Mice
Mice
Vies
-
-
vagrant shrew
deer mouse
Species diversity index
1.4
8.8
1.0
3.7
0.7
2.0
2.0
3.9
18.6
8.8
2.0
1.0
8.8
1.0
2.0
3.9
1.2
1.8
3.8
12.9
1.4
3.6
9.4
8.0
1.4
1.4
1.4
5.8
1.71
7.8
1.48
10.8
2.8
2.8
3.3
3.3
3.1
17.7
1.0
20.2
8.3
15.4
3.3
6.7
4.3
3.3
1.1
22.9
5.2
2.1
2.1
17.7
22.6
2.4
1.2
1.2
20.2
11.1
2.8
1.4
1.4
18.9
3.5
1.6
1.6
15.4
8.8
2.9
2.0
1.0
8.5
2.1
1.5
3.7
2.8
3.3
3.3
3.1
6.9
6.8
1.66
0.00
0.00
0.70
0.23
1.78
0.77
0.41
8.3
0.74
0.3
0.64
aInte,sive sampling areas were sampled 2, 3 or 4 consecutive nights in fall 1974 and 3 or 4 consecutive nights in spring 1975, but only the
first 2 nights were used to calculate captures ier 100 trap-nights.
binteiisive sampling areas of similar habitat combined; seasons combined.
CNumbers in parentheses equal trap-nights during first 2 nights.
dNot
captured, but was observed and/or identified by sign in this habitat.
Not captured until third night.
tNot recorded in intensive sampling areas, but was observed in this habitat.
capured in non-standardized traps only.
TABLE I.
Continued.
1labitat
Oak / Ponderosa Pine
Species or Group
Vagrant shrew
Pacific water shrew
Trowbridgc's shrew
Shrew-mole
Coast mole
Nuttall's cottontail
Snowshoe hare
Townsend's chipmunk
Yellow-bellied marmot
California ground squirrel
Western gray squirrel
Douglas' squirrel
Northern flying squirrel
Northern pocket gopher
Western Jiarvst mouse
Deer mouse
Bushy-tailed woodrat
Montane vole
Townsend's vole
Long-tailed vole
Total mammals
(TOMA)
TOMA - deer mouse + vagrant shrew
Insectivores
Insectivores - vagrant shrew
Mice
Mice - deer mOuse
Voles
Species diversity index
1
2
3
(270)C
/ Trap Station Type
Oak (234)
X
1
3
2
1.4
Grassland (168)
X
1
Z
3
Rock Rip-Rap (384)
X
1
2
3
X
d
0.5
0.4
1.2
d
d
g
g
1.4
1.4
4.9
11.9
2.4
6.4
16.7
1.1
9.7
16.7
1.4
14.4
0.8
16.7
37.5
4.9
4.9
0.00
13.1
1.2
1.2
1.2
11.9
0.31
2.4
6.8
0.4
0.4
2.4
0.4
6.4
0.00
0.10
35.0
18.3
26.3
27.1
1,4
35.0
18.3
26.8
0.5
25.7
35.0
18.3
26.3
25.7
1.4
2.8
e
20.8
0.5
0.5
25.0
d
2.1
1.6
22.9
27.5
2.6
e
17.8
1.1
16.7
0.23
18.1
1.4
11.1
16.7
0.27
15.7
0.8
1.4
0.5
9.7
14.4
0.38
0.29
22.2
5.6
37.5
18.1
1.4
2.8
37.5
0.82
2.1
0.00
25.5
0.5
2.1
1.6
0.31 0.38
20.8
0.20
0.00
0.00
0.07
aintensive sampling areas were sampled 2, 3 or 4 consecutive nights in fall
1974 and 3 or 4 consecutive nights in spring 1975, but only the
first 2 nights were used to calculate captures per 100 trap-nights.
binteiisive sampling areas of similar habitat combined; seasons combined.
cNumberS in parentheses equal trap-nights (luring first 2 nights.
captured, but was observed and/or identified by sign in this habitat.
eNO
captured until third night.
recorded in intensive sampling areas, but was observed in thi
Captured in non-standardized traps only.
habitat.
TABLE J.
Mean index of abundance values (captures per 100 trap-nights) A small mammal intensive sampling areas inventoried (hiring fa1l 1974
and spring 1975 in segment 5 of the Columbia River study area.
Intensive Sampling Area / Season
Oregon
Washington
Rabbitbrush Rabbitbrush
S.A. 1
F
Species or Group
(96)
c
S.A.
cottontail
Black-tailed jack rabbit
d
d
California ground squirrel
d
d
e
d
Nutta1l
Yellow-bellied matmot
Northern pocket gopher
Great Basin pocket mouse
Western harvest mouse
Deer mouse
Bushy-tailed woodrat
Total Mamimmais
('I'OMA)
TOMA
-
Deer Mouse
Mice
Mice
-
Deer Mouse
Grassland
S.A. 2
8
Sp
(66)
38.9
F
Washington
Grassland
S.A. 9
F
24.7
38.9
(60)
d
d
d
d
d
e
d
d
1.9
2.8
15.7
8.3
38.9
5.6
23.3
23.3
17.6
1.9
17.6
1.9
iLl
2.8
11.1
31.5
31.5
31.5
2.8
first 2 nights were used to calculate CaptureS per 100 trap-nights.
bNot all intensive sampling areas were sanipled during the spring sampling period; F
CNurnber in parentheses equal trap-ni ghts during first 2 nights.
dNot captured, but was observed and/or identified by sign in sampling
area.
tNot captured wit ii third night.
25.0
f
25.0
Sp
F
F
(96)
Rip-Rap
S.A. 7
Sp
25.0
(96)
(96)
(96)
25.6
4.1
29.t
4.1
25.6
i.
18.6
33.3
26.1
29.1
41.1
18.6
33.3
27.2
29.1
41.1
29.1
41.1
18.6 33.3
Sp
F
ii
ii
1.1
27.2
1.1
UInteIIslVe sampling areas were sampled 2, 3 or 4 consecutive nights in fall 1974 and 3
CCapttlrcd in non-s tanda rdi zed traps only.
S.A. 5
4
(78)
d
d
5.6
S.A.
(42)
a
24.7
S.A. 3
(60)
d
Rock
Rip-Rap
(42)
d
Washington
Rock
Sp
d
23.3
Oregon
F
(42)
5.6
Oregon
Willow
Sp
(78)
d
Oregon
Shrub
Willow
Rockcliff/
(66)
f
24.7
Oregon
Rockcliff/
or 4 consecutive nights in spring 1975, but only the
fall 1974; Sp= spring 1975.
TABLE K.
Small mammal captures per 100 trap-nights and species diversity index values by trap
station type in habitats inventoried in segment 5 of the Columbia River study area.a
llabitat' / Trap Station Type
Rabbitbrush (228)C
Species or Group
1
2
3
Rockcllff / Grassland (162)
X
1
2
3
X
Nuttall's cottontail
Black-tailed jack rabbit
Yellow-bellied marmot
California ground squirrel
Northern pocket gopher
Great Basin pocket mouse
Western harvest mouse
ecr mouse
Bushy-tailed woodrat
d
d
d
d
f
g
f
1.5
2.1
1.2
25.0
28.2
16.7
23.3
10.6
22.9
18.8
17.4
Total mammals (TOMA)
TOMA - deer mouse
25.0
28.2
16.7
23.3
12.1
18.8
Mice
Mice
25.0
28.2
16.7
23.3
12.1
25.0
2.1
25.0
2.1
0.29
18.6
1.2
18.6
1.2
0.22
(1
deer mouse
Siecies diversity index
0.00
0.00
0.00
0.00
1.5
1.5
0.37
18.8
0.00
aintensive sampling areas were sampled 2, 3 or 4 consecutive nights in fall 1974 and 3 or 4 con-
secutive nights in spring 1975, but only the first 2 nights were used to calculate captures per
100 trap-nights.
bintensive sampling areas of similar habitat combined; seasons combined.
cNufllbers in parentheses equal trap-nights during first 2 nights.
..
d
e
Not captured, but was observed and/or. identified by .sign in this habitat.
.
Not recorded. in .intensive sampling
areas, but was observed. in this habitat.
Captured in non-standardized traps only.
captured until third night.
.
N)
TABLE K.
Continued.
llabitat' / Trap Station Type
Shrub Willow (102)C
Species or Group
1
2
3
Willow (138)
X
1
2
3
d
Nuttall's cottontail
flock Rip-Rap (384)
X
1
2
3
X
d
e
f
(I
Black-tailed jack rabbit
YellowhdUjed marmot
California ground squirrel
Northern pocket gopher
Great Basin pocket mouse
Western harvest mouse
Deer mouse
Bushy-tailed woodrat
Total utaimnals
TOMA
-
(TOMA)
deer mouse
Mice
Mice - deer mouse
Species diversity index
33.3
40.0
16.7
300
33.3
40.0
16.7
33.3
40.0
16.7
0.00
0.00
0.00
'
29.6
28.6
16.7
25.0
30.0
29.6
28.6
16.7
25.0
30.0
29.6
28.6
16.7
25.0
5
0.00
0.00
0.00
0.00
0.00
26.4
1.4
27.8
1.4
26.4
0.20
0.8
43.3
1.7
45.8
2.5
44.2
0.8
0.25
0.3
21.7
21.7
21.7
0.00
30.5
1.0
31.8
1.3
30.8
0.3
(hiS
almitensive sampling areas were sampled 2, 3 or 4 consecutive nights in fall 1974 and 3 or 4 consecutive nights in spring 1975, but only time
first 2 nights were used to calculate captures per 100 trap-nights.
bintensive sampling areas of similar habitat onmbined; seasons combined.
CNumbers in parentheses equal trap-nights during first 2 nights.
dNot
eNO
captured, but was observed and/or identified by sign in this habitat.
recorded in intensive sampling areas, but was observed in this habtiat.
Captured iii non-standardized traps only.
captured until third night.
'IABLF
1..
Mean index of abundance values (captures per 100 trap-nights) in small mammal intensive sampling areas inventoried during fall 1974
and spring 1975 in segment 6 of the Columbia River study area.
Intensive Sampling Area
Oregon
Rock
Rip-Rap
S.A. 11
Sp
Species or Group
(96)
Bushy-tailed wocidrat
Montanc vole
Norway rat
House mouse
Total Mammals (TOMA)
TOMA
Deer Mouse
Mice
Mice
Deer Mouse
S.A.
F
(96)
d
Nut tall's cottontail
Black-tailed jack rabbit
Yellow-bellied marmot
Townsend's chipmunk
California ground squirrel
Northern pocket gopher
Great Basin pocket mouse
Ord's kangaroo rat
Western harvest moose
Deer mouse
Northern grasshopper mouse
(96)
Oregon
Talus
Washington
Talus
S.A. 16
1
Sp
F
(96)
(96)
Oregon
Rockcliff/
Grassland
S.A. 2
Sp
F
(96)
(96)
d
Washington
Iloekcliff/
seasoub
/
Oregon
Sagebrush
Grassland
S.A. 17
F
(72)
d
F
S.A. 3
Sp
(96)
d
(96)
d
Washington
Sagebrush
S.A. 18
F
d
d
d
e
d
d
d
d
d
e
d
S.A.
F
(60)
d
d
d
Oregon
Bitterbrush
(96)
Washington
Bitterbrush
4
S.A.
Sp
F
(96)
12
Sp
(96)
(96)
ci
d
d
d
d
I
d
d
1.1
2.2
4.8
6.1
6.1
3.0
2.2
6.1
2.0
2.0
3.3
d
28.3
d
28.3
28.3
38.3
d
38.3
38.3
31.5
19.4
0.9
2.0
32.4
0.9
31.5
21.5
2.0
19.4
46.9
e
46.9
46.9
46.5
25.9
0.9
0.9
47.4
0.9
46.5
26.9
0.9
25.9
11.1
e
8.8
1.4
31.5
39.6
1.9
3.7
1.1
1.1
d
12.5
31.5
39.6
31.5
39.6
1.4
12.5
1.4
14.4
10.7
14.4
10.7
6.3
4.1
6.3
4.1
14.3
8.1
14.3
8.1
8.2
6.1
8.2
6.1
Voles
a11105 ivc sampling areas were sampled 2, 3 or 4 consecutive nights in fall 1974 and 3 or 4 consecutive nights in spring 1975, but
only the
first 2 nights were used to calculate captures per 100 trap-nights.
bNot all intensive sampling areas were sampled during
the spring sampling period; F= fall 1974; Sp= spring 1975.
1Number in parentheses equal trap-nights during first
2 nights.
dNot captured, but was observed and/or
identified by sign in sampling area.
£Captured in non-standardized traps only.
Not captured until third night.
12.6
9.3
12.6
9.3
'l'ABLIi L.
Cont inued.
Intensive Sampling Area
Oregon
Rabbithrush
S.A. 5
F
Species or Group
-
Nuttall s cottontail
Black-tailed jack rabbit
.
Washington
Babbitbrush
Oregon
Grassland
S.A. 6
S.A. 13
Sp
(96)
(96)
d
d
d
ci
F
Sp
(96)
d
d
(96)
F
Grassland
Oregon
Cottonwood!
Willow
(96)
F
Sp
(96)
d
ci
d
d
d
d
d
d
P
Sp
i
Ord's kangaroo rat
Western harvest mouse
Deer mouse
d
6.3
63
LI
2.2
1.1
1.1
1.1
3.3
4.4
d
3.2
Mice
Mice
-
(78)
6.3
Doer Mouse
Voles
7.4
11.9
7.4
3.3
2.2
3.3
2.2
5.6
5.6
5.6
5.6
(96)
P
Sp
(78)
(78)
(78)
e
d
d
d
e
d
d
e
e
d
2.2
6.3
8.3
2.2
2.8
5.1
d
2.2
17.1
1.1
12.0
2.2
1.1
17.1
12.0
1.1
1.1
i.i
1.1
i
tNot captored until third night.
d
2.2
4.5
4.5
2.2
2.2
2.2
3.6
(I
39
ci
2.2
9.6
8.5
9.6
8.5
1.4
11.9
9.7
11.9
9.7
12.0
14.8
12.0
14.8
12.0
44
3.6 3.6
7.5 11.7
7.5 11.7
3.6 7.2
3.6 7.2
but only the
sampling areas were sampled 2, 3 or 4 consecutive nights in fall 1974 and 3 or 4 consecutive nights in spring 1975,
per
100
first 2 nights were used to calculate captures
trap-nights.
liNot all nteits lye sampling areas were sampled during the spring sampl lug period; F= fall 1974; Sp= spring 1975.
CNumhers in parentheses equal trap-nights during first 2 nights.
dNot captured, but was observed and/or identified by sign iii sampl lug area.
Capt ured in non-s tandardi zed traps only.
U1S,0
(78)
1.1
12.0
3.2
Uussian
Olive
S.A. 9
Sp
d
1.1
3.2
3.2
3.2
F
d
0.9
0.9
0.9
0.9
0.9
S.A. 15
Sp
d
LI
6.3 11.9
(96)
8
(60)
(60)
Northern grasshopper mouse
Bushy- tal led wuodrat
Montane vole
Norway rat
house mouse
Total hlammals (TOMA)
lOMA - Deer Mouse
S.A.
Oregon
Marsh
Marsh
F
F
Washington
Oregon
d
d
fornia ground squirrel
Northern pocket gopher
Great Basin pocket mouse
Washington
Cottonwood!
Willow
(96)
Yellow-bellied mansot
Townsend's ground squirrel
Cal
easonb
S.A. 19
S.A. 7
S.A. 14
Sp
(96)
Washington
/
TABLE M.
Small mammal captures per 100 trap-nights and species diversity index values by trap station type in habitats inventoried in
segment 6 of the Columbia River study area.a
Habitat" / Trap Station Type
(192)C
Rock Rip-Rap
Species or Group
1
2
3
Talus (288)
X
1
2
3
d
Nuttall's cottontail
White-tailed jack rabbit
Black-tailed jack rabbit
Yellow-bellied marmot
Townsend's ground squirrel
California ground squirrel
Northern pocket gopher
Great Basin pocket mouse
Rockcliff / Grassland (264)
1
1
2
3
I
d
d
d
d
d
e
1.2
0.4
16.7
29.4
Ord' a kangai'oo rat
Western harvest mouse
Doer mouse
Northern grasshopper mouse
Bushy-tailed woodrat
Montane vole
Norway rat
house mouse
Total mammals
(TOMA)
1T4A - deer mouse
Mice
Mice - deer mouse
Species diversity index
33.3
43.3
23.3
33.3
d
33.3
33.3
0.00
43,3
43,3
0.00
23.3
23.3
0.00
33.3
33.3
0.00
33.3
37.8
1.9
1.1
35.2
38.9
1 .9
1. 1
33.3
37.8
0.21
0.13
26.7
26.7
26.7
0.00
32.6
32.3
1.0
2.1
33.6
34.4
1 .0
2. 1
32.6
32.3
0.11
0.23
39.3
0.7
39.3
39.3
0.00
17.9
1.2
17.9
1.2
0.25
30.5
1 .
29.8
0.4
0.16
aI,,tensivo sampling areas were sampled 2, 3 or 4 consecutive nights in fall 1974 and 3 or 4 consecutive nights in spring
1975, but only the
first 2 nights were used to calculate captures per 100 trap-nights.
hltitensive sampling areas of
similar habitat combined; seasons combined.
cNUWbCIS in patentheses equal trap-nights during first 2 nights.
dNOt captured, but was observed
and/or identified by sign in this habitat.
°Capturod in non-standardized traps only.
N0t recorded jn intensive sampling areas, but was observed in this habitat.
8Not captured until third night.
-'
0"
TABLE M.
Cc.ntinucd.
I!abitat
Rabbitbrush (384)
Sagebrush (252)C
Species or Group
1
Nuttall's cottontail
White-tailed jack rabbit
Black-tailed jack rabbit
Yellow-bellied marmot
Townsend's ground squirrel
California ground squirrel
Northern pocket gopher
Great Basin pocket mouse
Ord's kangaroo rat
Western harvest mouse
Deer mOuse
Northern grasshopper mouse
Bushy-tailed woodrat
Montane vole
Norway rat
house mouse
fetal rnan',j,als
2
3
/ Trap Station Type
X
1
2
3
X
Bitterbrush (384)
1
2
3
X
Grassland (384)
1
2
X
3
f
d
d
d
d
d
f
e
1.0
5.1
1.3
25.0
38.5
2.0
1.4
0.4
20.5
28.0
1.4
0.8
3.3
6.7
5.0
0.8
0.8
1.4
3.0
4.2
4.2
0.7
2.8
3.3
4.2
1.7
0.8
4.2
0.8
3.3
0.8
3.9
2.0
0.8
3.4
0.3
0.7
0.7
2.5
1.1
0.2
0.8
0.3
3.3
2.5
3.3
2.5
0.55
1.6
1.3
1.6
1.3
g
26.0
39.7
25.6 30.4
1.3
5.1
2.5
26.0 39.7 25.6
30.4
1.0
1.3
5.1
2.5
0.16 0.14 0.50 0.27
(TOMA)
TONA - decr mouse
Mice
Mice - deer mouse
Species diversity index
1.0
2.8
1.4
2.8
10.8
4.2
10.8
4.2
1.4
0.69 0.85
6.7
5.8
6.7
5.8
0.73
6.8
3.8
6.8
3.8
0.76
11.8
9.0
11.8
9.0
1.24
8.3
10.8
10.3
4.2
7.5
6.9
8.3 10.8
10.3
4.2
7.5
6.9
0.94 1.41 1.20
1.4
1.4
1.4
1.4
0.69
0.00
0.41
"Intensive sampling areas were sampled 2, 3 or 4 consecutIve nights in fall 1974 and 3 or 4 consecutive nights in spring 1975, but only the
first 2 nights were used to calculate captures per 100 trap-nights.
bintensive sampling areas of similar habitat combined; seasons combined.
'Numbers in parentheses equal trap-nights during first 2 nights.
dNot captured, but was observed and/or identified by sign in this habitat.
eCd in non-standardized
traps only.
recorded in intensive sampling areas, but was observed in this habitat.
captured until third night.
TABLE H.
Continued.
Ilabitat
Russian Olive (156)
Cottonwood / Willow (198)C
Species or Group
1
2
3
/ Trap Station Type
X
1
2
3
d
Nuttail's cottontail
White-tailed jack rabbit
Black-tailed jack rabbit
Marsh (312)
X
1
2
3
e
X
d
Yellow-bellied marmot
lowasend's ground squirrel
California ground squirrel
e
Northern pocket gopher
Great Basin pocket mouse
Ord's kangaroo rat
Western harvest mouse
2.6
1.3
Deer mouse
Northern grasshopper mouse
Bushy-tai[ed woodrat
Montane vole
Norway rat
-
3.3
1.3
house mouse
Total mammals (fOMA)
TOMA - deer mouse
Mice
Mice
8.3
5.1
3.8
3.8
2.6
deer mOuse
Species diversity index
1.04
c
3.6
1.5
3.3
8.3
8.3
8.3
8.3
0.00
3.3
3.3
0.00
5.6
4.0
5.1
3.6
0.35
8.3
6.7
18.3
18.3
10.0
10.0
trap-nights during first 2 nights.
captured, but was observed and/or identified by s:ign in this habitat.
ecaptured in non-standardized traps only.
KNOt recorded in intensive sampling areas, but was observed in this habitat.
dNot
captured until third night.
1.8
1.7
1.7
d
0.4
aintejisive sampling areas were sampled 2, 3 or 4 consecutive nights in fall
the first 2 nights were used to calculate captures per 100 trap-nights.
bimitensive sampling areas of similar habitat combined; seasons combined.
CNumnbers in parentheses equal
2.2
1.04
1974
4.2
2.1
6.3
6.3
2.1
2.1
0.64
2.1
4.2
4.2
4.2
4.2
0.69
4.2
3.6
9.6
9.6
5.4
5.4
0.79
6.3
2.1
6.3
1.3
0.7
2.1
1.7
5.0
3.3
5.0
3.3
1.10
3.1
13.5
11.5
11.5
9.4
1.27
4.8
d
3.1
9.4
9.4
9.4
9.4
0.63
2.6
9.3
8.1
8.6
7.4
1.00
and 3 or 4 consecutive nights in spring 1975, but only