Ecological distribution of small mammals at Sarpy Creek, Montana, with special consideration of the
deer mouse, Peromyscus maniculatus
by Kenneth Lee Scow
A thesis submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE
in Zoology
Montana State University
© Copyright by Kenneth Lee Scow (1981)
Abstract:
In conjunction with the development of coal mining activities, a study of the ecological distribution of
small mammals was conducted in the Sarpy Creek area of southeastern Montana from 1975-1976.
Small mammal species were snap trapped in six important vegetation types and live trapped in the
ponderosa pine, skunkbush sumac and grassland types. Small mammal species were distributed
ecologically as expected, and results agreed with similar studies which have been conducted in
southeastern Montana from 1975-1980. Small mammal diversity was highest in the grassland type,
followed in order by the shrubland and woodland types. The species most commonly trapped at Sarpy
Creek was the deer mouse (Peromyscus maniculatus).Deer mouse densities, based upon calculations of
nome range size, averaged three to four individuals per hectare in the pine type and one to two
individuals per hectare in the shrubland and grassland types. These densities generally agreed with
those found in the aforementioned studies. Computer analyses were run to correlate the trapping
success of deer mice with vegetation species frequency of occurrence and canopy coverage on the three
live trap grids. A limited number- of correlations were found by discriminant analysis, probably due to
the nature of the system tested and/or field methodology. Correlations could not be attributed to plants
as a food source. Canopy cover comparisons indicated that deer mice on the pine grid showed a
positive correlation with bare ground and a negative correlation with tree cover. STATEMENT OF PERMISSION TO COPY
In p r e s e n t i n g t h i s t h e s i s in p a r t i a l f u l f i l l m e n t o f t h e r e q u i r e ­
ments f o r an advanced d e g r e e a t Montana S t a t e U n i v e r s i t y , I a g r e e t h a t
t h e L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r i n s p e c t i o n .
I further
a g r e e t h a t p e r m i s s i o n f o r e x t e n s i v e copyi ng o f t h i s t h e s i s f o r
s c h o l a r l y p u r p o s e s may be g r a n t e d by my m a jo r p r o f e s s o r , o r , i n h i s
a b s e n c e , by t h e D i r e c t o r o f L i b r a r i e s .
I t i s u n d e r s to o d t h a t any
co pyi ng o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l n o t be
a l lo w ed w i t h o u t my w r i t t e n p e r m i s s i o n .
Signature
ECOLOGICAL.DISTRIBUTION OF SMALL MAMMALS AT SARPY CREEK,
MONTANA, WITH SPECIAL CONSIDERATION OF THE
DEER MOUSE, PEROMYSCUS MANICULATUS
by
KENNETH LEE SCOW
A t h e s i s s u b m i t t e d in p a r t i a l f u l f i l l m e n t
of th e requirements f o r the degree
of
MASTER OF SCIENCE
in
Zoology
Approved:
Chairman, G rad u ate Committee
iad, Major Department
G r ad ua te Dean
MONTANA STATE UNIVERSITY
Bozeman, Montana
Au gust, 1981
iii
ACKNOWLEDGEMENT'
I wish t o e x p r e s s my a p p r e c i a t i o n t o t h e f o l l o w i n g p e o p l e who
c o n t r i b u t e d t o t h e c o m p le ti o n o f t h i s s t u d y :
Dr. Ro b er t E. Moore,
Montana S t a t e U n i v e r s i t y , f o r h i s p a t i e n t s u p e r v i s i o n and gu idance
t h r o u g h o u t t h e p r o j e c t ; Dr. Harold D. P i c t o n , Dr. Ro b er t Eng and
Dr. Tad Weaver who revie we d t h e m a n u s c r i p t ; Dr. Dalton B u r k h a l t e r f o r
h i s i n v a l u a b l e a s s i s t a n c e in the, p r e p a r a t i o n o f computer programs
and s t a t i s t i c a l
t e s t s ; Edward D a r f l e r , who p r o v i d e d much needed
e n c ou r a ge m en t; Mr. P a t r i c k Farmer, WESTECH, f o r h i s t e c h n i c a l e x p e r ­
t i s e and a d v i c e i n t h e i n t e r p r e t a t i o n o f d a t a ; p e r s o n n e l o f WESTECH
who most g e n e r o u s l y d o na te d t h e i r ti m e t o t h e p r e p a r a t i o n o f t h i s
manuscript:
Dean C u l w e l l , D arl ene Woxen, Carol Cloug h.a nd Li sa L a r s e n ;
Dr. Lyman McDonald, U n i v e r s i t y o f Wyoming, who p r o v i d e d t h e J o l l y S eb er computer program.
The s t u d y was funded by AMAX Coal Company.
TABLE OF CONTENTS
Page
V I T A ................................
. . ....................... ................................................................ Ti
ACKNOWLEDGEMENT..................................................
iii
LIST OF TABLES . ................................................................................................................ vi
LIST OF FIGURES. ..........................................................................
. . . . . .
.v iii
ABSTRACT .....................................................
ix
INTRODUCTION . . ...................................................................................................................I
DESCRIPTION OF THE STUDY AREA...............................................................................
3
METHODS. . ............................................................
6
V e g e t a t i o n .......................................................................................
6
Small Mammal T r a p p i n g ..................."..............................................................
7
RESULTS....................................................................................................................................... 12
V e g e t a t i o n T y p e s .......................................................................................................12
Ponderosa P in e Type ..............................................................................
Skunkbush Sumac T y p e ............................................
G r a s s l a n d Type .........................................., ...........................................21
S i l v e r S age br us h Type. . . . . . . .
.....................................
R i p a r i a n Deciduous T ree Type . . . .
.......................
Deciduous Shrub Bottom Type. . . .............................................
Snap T r app in g S u r v e y ..................................................
12
20
21
22
22
23
Live Tr ap p i n g S u r v e y ............................................................................................. 26
C o rre la tio n o f Vegetation Features with
T r ap p in g Su cc es s o f Deer M i c e .................................................................. 35
DISCUSSION.....................................
39
Deer Mouse D i s t r i b u t i o n / V e g e t a t i on C o r r e l a t i o n s ..........................
4Q
Comparison o f R e s u l t s w i t h S i m i l a r S o u t h e a s t e r n
Montana S t u d i e s ...........................................................
42*
V
TABLE OF CONTENTS
( Co nti nue d)
Page
LITERATURE C I T E D ............................................... ......................................................... 53
APPENDIX........................................................................................................................... 5g
vi
LIST OF TABLES
Tabl e
1.
2.
3.
4.
5.
6.
7.
8.
9.
Page
DATES OF SNAP TRAPPING ALONG LINES IN SEVEN
HABITATS. REFER TO FIGURE I FOR LOCATIONS
OF THE L I N E S ......................................................................................................
8
MEAN PERCENT COVER BY COVER CLASS FOR SIX
VEGETATION TYPES AT SARPY CREEK, MONTANA
1975-1976...........................
13
MEAN PERCENT COVER FOR SHRUB AND TREE SPECIES
FOR SIX VEGETATION TYPES AT.SARPY CREEK, MONTANA,
197 5- 197 6..............................................................................
14
PERCENT FREQUENCY OF OCCURRENCE/MEAN COVERAGE RANK
FOR GRAMINQID. FORB AND SUBSHRUB SPECIES WHICH
OCCURRED AT 20 PERCENT OR GREATER FREQUENCIES IN SIX
VEGETATION TYPES AT SARPY CREEK, MONTANA, 1975-1976. . . .
15
PERCENT SUCCESS OF SNAP TRAPPING SMALL MAMMALS,
SARPY CREEK, MONTANA, 1975-1976..................................... ......................
24
POOLED' DATA ON NUMBERS OF DEER MICE CAUGHT ALONG
SNAP TRAP LINES AND NUMBER OF DEER MICE PER 100
TRAP-NIGHTS OF EFFORT FOR EACH TRAPPING PERIOD .......................
26
POOLED DATA FROM ALL VEGETATIVE TYPES OF NUMBERS
OF DEER MICE IN REPRODUCTIVE CONDITION AND NUMBERS
OF JUVENILES CAUGHT DURING EACH SNAP TRAPPING PERIOD . . .
27
NUMBERS OF SMALL MAMMALS CAPTURED ON LIVE TRAP GRIDS
BY TRAPPING PERIOD, SARPY CREEK, MONTANA, 1975-1976. . . .
28
AGE AND SEX RATIOS OF DEER MICE FOR LIVE TRAP GRIDS,
SARPY CREEK, MONTANA, 1975-1976............................................................
30
10.
MEANS AND RANGES OF HOME RANGE SIZES IN HECTARES
FOR DEER MICE ON THE THREE LIVE TRAP GRIDS. HOME
RANGES ARE CALCULATED FROM CAPTURES ONLY WITHIN
EACH SINGLE 6-NIGHT TRAPPING-PERIOD;....................... • .................... 31
11.
ESTIMATES OF POPULATION DENSITY (INDIVIDUALS/HECTARE)
FOR SOME SPECIES OF SMALL MAMMALS ON THREE SARPY CREEK
LIVE-TRAPPED HABITATS................................................................................... 34
v1 i
LIST OF TABLES
( Co nti nue d)
Ta b le
Page
12.
POPULATION ESTIMATES (INDIVIDUALS/HECTARE) FOR
DEER MICE IN TWO SARPY CREEK VEGETATION TYPES
USING JOLLY-SEBER MODEL OF ANALYSIS.............................................. 35
13.
COMPARISON OF RELATIVE DENSITIES OF DEER MICE
AS DETERMINED BY THE NUMBER OF CAPTURES PER
100 TRAP NIGHTS (LIVE AND/OR SNAP TRAPPING)
IN SOUTHEASTERN MONTANA.
............................................................ 44
14.
COMPARISON OF DEER MICE DENSITIES (INDIVIDUALS/
HECTARE) FOR FOUR SOUTHEASTERN MONTANA STUpiES ...................
15.
NUMBER OF ,SOUTHEASTERN MONTANA STUDIES IN WHICH
SPECIES OF SMALL MAMMALS WERE RECORDED AS PRESENT
IN COMMON VEGETATION TYPES. REFER TO TABLE 13 FOR
A LISTING OF THE 19 STUDIES SURVEYED..........................................50
16.
SPECIES LIST OF SMALL MAMMALS, SARPY CREEK, MONTANA. . .
17.
SARPY CREEK PLANT SPECIES LIST . . . ..........................................62
18.
PERCENT FREQUENCY OF OCCURRENCE OF GRAMINOID, '
FORB AND SUBSHRUB SPECIES FOR VEGETATION TYPES
AT SARPY CREEK, MONTANA, 1975-1976 ..............................................
49
60
69
yiii
LIST OF FIGURES
Figure
1.
2.
3.
Page
Map o f t h e s t u d y a r e a showing l o c a t i o n s o f snap
t r a p l i n e s and l i v e t r a p g r i d s .
R e f e r t o page 7
o f t e x t f o r i d e n t i f i c a t i o n o f v e g e t a t i o n ty p e s
o f snap t r a p p i n g l i n e s ' . ..
....................... ............................ ....
.
4
S i z e d i s t r i b u t i o n o f a l l p o n d er o s a p i n e t r e e s on
t h e p on de r o s a p i n e l i v e t r a p g r i d , Sarpy Creek,
Montana, 1976 ........................................................ . . . . . . . . .
18
Age d i s t r i b u t i o n s o f t e n p o nd er o s a p i n e t r e e s f o r
each f i v e c e n t i m e t e r dbh c l a s s . Mean ages a r e
s h o w n ............................................................................................................... ...
19
ix
ABSTRACT
In c o n j u n c t i o n with, t h e devel opment o f coal mining a c t i v i t i e s , a
s t u d y o f t h e e c o l o g i c a l d i s t r i b u t i o n o f small mammals was conducted
i n t h e Sarpy Creek a r e a o f s o u t h e a s t e r n Montana from 1975-1976. Small
mammal s p e c i e s were snap t r a p p e d in s i x i m p o r t a n t v e g e t a t i o n ty p e s
and l i v e t r a p p e d i n t h e po n d ero sa p i n e , skunkbush sumac and g r a s s l a n d
types.
Small mammal s p e c i e s were d i s t r i b u t e d e c o l o g i c a l l y as ex p e c te d ,
and r e s u l t s a g r e e d w i t h s i m i l a r s t u d i e s which have been con ducted in
s o u t h e a s t e r n Montana from 1975-1980. Small mammal d i v e r s i t y was
h i g h e s t in t h e g r a s s l a n d t y p e , f o l l o w e d i n o r d e r by t h e s h r u b l a n d and
woodland t y p e s . The s p e c i e s most commonly t r a p p e d a t Sarpy Creek was
t h e d e e r mouse ( Peromyscus m a n i c u l a t u s ) . JDeer mouse d e n s i t i e s , based
upon c a l c u l a t i o n s o f nome r an g e s i z e ! a v e r a g e d t h r e e t o f o u r
i n d i v i d u a l s p e r h e c t a r e in t h e p in e t y p e and one t o two i n d i v i d u a l s p e r
h e c t a r e in t h e s h r u b l a n d and g r a s s l a n d t y p e s . These d e n s i t i e s
g e n e r a l l y ag r e e d w i t h t h o s e found in t h e a f o r e m e n t i o n e d s t u d i e s . Com­
p u t e r a n a l y s e s were run t o c o r r e l a t e t h e t r a p p i n g s u c c e s s o f d e e r mice
w i t h v e g e t a t i o n s p e c i e s f r e q u e n c y o f o c c u r r e n c e and canopy co ver ag e
on t h e t h r e e l i v e t r a p g r i d s . A l i m i t e d number- o f c o r r e l a t i o n s were
found by d i s c r i m i n a n t a n a l y s i s , p r o b a b l y due t o th e n a t u r e o f t h e
system t e s t e d a n d / o r f i e l d methodology. C o r r e l a t i o n s c o u l d n o t be '
a t t r i b u t e d t o p l a n t s as a food s o u r c e . Canopy c o v e r com parisons
i n d i c a t e d t h a t d e e r mice on t h e p i n e g r i d showed- a p o s i t i v e c o r r e l a t i o n
w i t h b a r e ground and a n e g a t i v e c o r r e l a t i o n w it h t r e e c o v e r .
INTRODUCTION
Hoffmann and P a t t i e (1968) e x p r e s s e d t h e need f o r a d d i t i o n a l
i n f o r m a t i o n on t h e d i s t r i b u t i o n and h a b i t a t r e q u i r e m e n t s o f numerous
small mammal s p e c i e s i n Montana, e s p e c i a l l y i n t h e e a s t e r n s e c t i o n o f
the s t a t e .
Few s t u d i e s o f t h e e c o l o g i c a l d i s t r i b u t i o n o f small mam­
mals had been co n d u ct ed i n e a s t e r n Montana p r i o r t o e x p l o r a t i o n f o r
and development o f coal mining a c t i v i t i e s , i n t h e r e g i o n d u r i n g t h e
1970's.
-
The Montana S t r i p and Underground Mine Reclamation Act ( T i t l e 50,
C h a p t e r 10, R.C.M. 1947) r e c o g n i z e d t h e im p o rta nc e o f small mammals in
complex e c o s y s te m s .
B a s e l i n e s t u d y g o a l s were o u t l i n e d t o d e t e r m in e
p r e - m i n i n g small mammal community s t r u c t u r e i n terms o f s p e c i e s d i v e r ­
s i t y and d e n s i t i e s in r e l a t i o n t o h a b i t a t .
A major t h e o r e t i c a l con­
t e n t i o n was t h a t r e c l a m a t i o n o f d i s t u r b e d la n d may be c o n s i d e r e d to be
p r o g r e s s i n g f a v o r a b l y when small mammal p o p u l a t i o n s in r e c l a i m e d a r e a s
resemble pre-mining p o p u la tio n s.
Thi s s u r v e y o f small mammals was c o n d u ct ed i n t h e Sarpy Creek,
Montana a r e a d u r i n g t h e summers o f 1975 and 1976 and d u r i n g s h o r t
t r i p s t o t h e a r e a i n F eb r u ar y and May, 1976.
The o b j e c t i v e s o f t h e
s t u d y were t o :
1)
d e s c r i b e t h e m a jo r v e g e t a t i o n t y p e s on t h e s t u d y a r e a ;
2)
u t i l i z e snap t r a p p i n g p r o c e d u r e s t o compare r e l a t i v e
d e n s i t i e s o f small mammal s p e c i e s i n pr ed om in an t .
Sarpy Creek v e g e t a t i o n t y p e s ;
2
3)
c a l c u l a t e home r a n g e s and d e n s i t i e s o f d e e r mice
( Peromyscus m a n i c u l a t u s ) from l i v e t r a p p i n g in
th r e e im portant v eg etatio n t y p e s ;
4)
c o r r e l a t e v a r i o u s f e a t u r e s o f v e g e t a t i o n on t h e
th r e e l i v e tr a p s i t e s with tra p p in g success o f
d e e r m ic e; and
5)
compare t r a p p i n g s u c c e s s o f d e e r mice and o t h e r
s p e c i e s o f small mammals a t Sarpy Creek w it h t h e
r e s u l t s o f r e c e n t small mammal s u r v e y s in o t h e r
a r e a s o f s o u t h e a s t e r n Montana.
DESCRIPTION OF THE STUDY AREA
The Sarpy Creek s t u d y a r e a i s l o c a t e d in s o u t h e a s t e r n Montana
a p p r o x i m a t e l y 30 m i l e s s o u t h o f Hysham and 40 m i l e s e a s t o f Hardin.
The a r e a i n c l u d e s a p p r o x i m a t e l y 14,770 h e c t a r e s o f p a r t s o f Townships
1-3 N o r t h , . Ranges 37 and 38 E a s t a t t h e j u n c t i o n o f Big Horn, T r e a s u r e
and Rosebud C o u n ti e s ( F i g u r e I ) .
The s t u d y a r e a encompasses p o r t i o n s
o f t h e d r a i n a g e s o f S a r p y , E a s t Fork Sarpy and Horse Cr eek s.
The Tongue R iv e r Member o f t h e F o r t Union Formation i s t h e p r i n ­
cip a l geologic f e a t u r e of th e study a r e a .
The pr im ar y s o i l a s s o c ­
i a t i o n s a r e t h e F l a s h e r - B a i n v i T l e and t h e B a i n v i l l e - M i d w a y , both
having low t o m ode rat e w a t e r s t o r a g e c a p a b i l i t i e s ( S o i l C o n s e r v a ti o n
S e r v i c e , 1967).
The c l i m a t e i s s e m i - a r i d w it h h o t , d r y surnmers and
moderately c o ld , dry w in te r s .
Lowest a v e r a g e monthly p r e c i p i t a t i o n
o c c u r s d u r i n g F e b r u a r y ( 0 . 4 i n c h e s ) and t h e h i g h e s t d u r i n g June
( 2 . 6 i n c h e s ) (NOAA, 1976).
Broad c r e e k bottoms al o ng ma jor d r a i n a g e s such as Sarpy Creek
s u p p o r t r i p a r i a n v e g e t a t i o n dominated by dec id u ou s t r e e s p e c i e s .
G rain and a l f a l f a a g r i c u l t u r e i s l i m i t e d t o t h e b o t t o m l a n d s .
Creek
bottoms g r a d e i n t o r o l l i n g f o o t h i l l s dominated by s t a n d s o f big
s a g e b r u s h ( A r t e m i s i a t r i d e n t a t a ) and some s i l v e r s a g e b r u s h (A r t e m i s i a
cana) .
There i s a l s o open g r a s s l a n d composed o f w h e a tg r a s s /g r a m a
g r a s s a s s o c i a t i o n s (A g r o p y r o h / B o u t e l o u a ) .
WelI - d i s s e c t e d , sometimes
rugged up la nd a r e a s a r e c h a r a c t e r i z e d by i r r e g u l a r , m o s t l y open
4
HORSE CREEK ROAD
grass
1000 meters
F ig . I .
Map o f t h e s tu d y a r e a showing l o c a t i o n s o f snap t r a p
l i n e s and l i v e t r a p g r i d s .
Ref er to page 7 o f t e x t
f o r i d e n t i f i c a t i o n o f v e g e t a t i o n typ e s o f snap t r a p p i n g
lines.
5
s t a n d s o f pond ero sa p i n e ( Pinus p o n d e r o s a ).
Many upland s i t e s a r e
domin ated by skunkbush sumac ( Rhus t r i l o b a t a ) and s i l v e r s a g e b r u s h , as
well as b ig s a g e b r u s h and w h e a t g r a s s / g r a m a g r a s s l a n d .
Where upland
bottoms a r e n o t dominated by po n d ero sa p i n e , a d e ci du o u s s h r u b a s s o c ­
i a t i o n o f haw thorn/chokecherry/rose (Crataegus/Prunus v irginiana/R osa
woodsi i ) u s u a l l y d o m i n a t e s .
Al I p o r t i o n s o f t h e s t u d y a r e a a r e
u t i l i z e d f o r. g r a z i n g o f l i v e s t o c k .
METHODS
Vegetation
Q u a n t i t a t i v e measurements o f t h e v e g e t a t i o n on t h r e e l i v e t r a p '
g r i d s and a l o n g t h r e e snap t r a p l i n e s were made t o d e s c r i b e t h e impor­
t a n t h a b i t a t s f o r small mammals.
Al I p i n e t r e e s on t h e po nd erosa p i n e
l i v e t r a p p l o t were c o u nt ed and c l a s s i f i e d a c c o r d i n g t o 5 cm dbh
c l a s s e s in Aug ust , 1975.
Core samples were t a k en from t e n specimens
o f each dbh c l a s s on t h e p l o t .
.
In Au gus t, 1976, a c i r c u l a r p l o t method was employed t o measure
v e g e t a t i o n on t h e t h r e e l i v e t r a p p l o t s .
p
The c e n t e r o f a 4 m c i r c u ­
l a r p l o t ( 1 . 1 3 m r a d i u s ) was p l a c e d a t each o f t h e 225 s t a t i o n markers
o f a gi ve n l i v e t r a p p l o t .
At each s t a t i o n a l l t r e e s , s hr u b and
h er ba c eo us s p e c i e s w i t h i n t h e c i r c u l a r p l o t were r e c o r d e d .
Woody
p l a n t s 2 . 5 m o r g r e a t e r i n h e i g h t were c l a s s i f i e d as t r e e s and t h o s e
between 0 . 2 5 and 2 . 5 m as s h r u b s .
Al I non-woody s p e c i e s as well as
p l a n t s l e s s th a n 0 . 2 5 m were c o n s i d e r e d t o be h e r b s .
P e r c e n t cov era ge
w i t h i n each c i r c u l a r p l o t was e s t i m a t e d t o t h e n e a r e s t f i v e p e r c e n t
f o r th e following c l a s s e s :
and l i c h e n s .
r o c k , b a r e g r o u nd , l i t t e r , g r a s s e s , fo ^bs
T ree and s h ru b canopy c o v e r a g e s were e s t i m a t e d by
s p e c i e s i n t h e same manner.
The h e r b a c e o u s s p e c i e s p r e s e n t a t each
s t a t i o n were l i s t e d i n o r d e r from g r e a t e s t t o l e a s t c o v e r a g e .
These
r a n k i n g s were a v e r a g e d by s p e c i e s f o r ea ch p l o t to o b t a i n a r e l a t i v e
ind ex o f c o v e r a g e .
7
The c i r c u l a r p l o t method was used t o o b t a i n s i m i l a r v e g e t a t i o n a l
d a t a f o r t h r e e i m p o r t a n t h a b i t a t s n o t r e p r e s e n t e d by t h e l i v e t r a p
plots.
Data were o b t a i n e d in Au gu st, 1976, on t h e f o l l o w i n g snap ,
trap lin es:
"N11 ( s i l v e r s a g e ) , " I " ( d e c i d u o u s s hr u b b o t t o m ) , and "J"
(bottomland) (Figure I ) .
A c i r c u l a r p l o t was p l a c e d a t each o f t h e
20 s t a t i o n s o f each t r a p l i n e and a t a su p p le m e n ta r y 20 s t a t i o n s on a
l i n e p a r a l l e l t o and 30 m from each t r a p l i n e .
P l a n t specimens from t h r o u g h o u t t h e s t u d y a r e a were c o l l e c t e d and
pressed.
These were l a t e r i d e n t i f i e d by r e f e r e n c e t o Booth and Wright
( 1 9 6 6 ) , v e r i f i e d by Dr. J . Rumely, c u r a t o r o f t h e Montana S t a t e
U n i v e r s i t y h e r b a r i u m , and compiled i n t o a s p e c i e s l i s t .
Small Mammal T r app in g
E i g h te e n snap t r a p l i n e s were e s t a b l i s h e d in seven m a jo r h a b i ­
tats
( F i g u r e I ) , and small mammals were sampled al o n g t h e l i n e s d u r i n g
fiv e trapping periods.
a r e g iv e n below.
The h a b i t a t s and t h e i r r e s p e c t i v e t r a p l i n e s
Ta b le I g i v e s t h e s c h e d u l e f o r snap t r a p p i n g .
V e g e t a t i o n Type
T rap lin e Designations
Ponderosa Pine
A, B, C, D, E, Q
Skunkbush Sumac .
F, G, H
Deciduous Shrub Bottom
I
R i p a r i a n Deciduous Tree
J
S i l v e r Sagebrush
K, L. M, N
Big Sagebrush
0, P
Grassland
R
8
TABLE 1 . — DATES OF SNAP TRAPPING ALONG LINES IN SEVEN HABITATS.
TO FIGURE I FOR LOCATIONS' OF THE LINES
Date o f
T r ap pi n g
Period
17 August - 6 S ep te mb er, 1975
17-19 F e b r u a r y , 1976
22-24 May, 1976
18-25 J u l y , 1976
'
Vegetation
Type
A,
Sumac
F
S i l v e r Sage
K
Big Sage
O
L
Grassland
R
Ponderosa Pine
D,
Sumac
F
Deciduous Shrub Bottom
I
Big Sage
P
Ponderosa Pine
D,
Sumac
G
Deciduous Shrub Bottom
. I
J
S i l v e r Sage
M
Pondprosa Pine
E
Sumac ■
H
■
Deciduous Shrub Bottom
•
. C
S i l v e r Sage
• R i p a r i a n Deciduous Tree
12-17 S ep te mb er, 1976
Lines
Trapped
Ponderosa Pine
Ponderosa Pine
R i p a r i a n Deciduous Tree
S i l v e r Sage
REFER
" I
J
• N
9
Each snap t r a p l i n e c o n s i s t e d o f 20 s t a t i o n s , spa ced 15 m a p a r t .
Three Museum S p e c i a l snap t r a p s , b a i t e d w it h p e a n u t b u t t e r and o a t s ,
were s e t w i t h i n I m o f each s t a t i o n m ark er .
th ree consecutive n ig h ts.
and r e s e t .
Each l i n e was tr a p p e d f o r
Traps were checked each morn in g, r e b a i t e d
Animals were c o l l e c t e d , ta g g e d and r e c o r d e d as t o s p e c i e s ,
s e x , age and r e p r o d u c t i v e c o n d i t i o n .
L a t e r , s t a n d a r d l e n g t h measure­
ments were made, and each animal was d i s s e c t e d t o d e t e r m i n e i t s r e p r o ­
ductive s ta t u s .
mm in m a le s .
T e s t i s l e n g t h and w i d t h were measured t o t h e n e a r e s t
In f e m a l e s , any embryos p r e s e n t were c o u n t e d and
measured a l o n g t h e i r l o n g e s t axe s. .
Males were d e s i g n a t e d as bei ng in
r e p r o d u c t i v e c o n d i t i o n i f t e s t e s l e n g t h s were 8 mm o r l o n g e r (Sheppe,
1963).
Females were ju d g e d as t o r e p r o d u c t i v e c o n d i t i o n by t h e p r e s ­
ence o f embryos, s i z e o f r e p r o d u c t i v e t r a c t s o r e x t e r n a l a p p e a r a n c e o f
mammae and g e n i t a l a r e a s .
Three l i v e t r a p p l o t s were e s t a b l i s h e d i n common h a b i t a t s o f t h e
Sarpy Creek d r a i n a g e , each dominated by a d i s t i n c t l y d i f f e r e n t
physiognomic form o f v e g e t a t i o n ( F i g u r e I ) .
One woodland p l o t was
e s t a b l i s h e d i n a. r a v i n e s t a n d o f p o n d er o s a p i n e ( Pinus p o n d e r o s a ).
A s h r u b l a n d p l o t was l o c a t e d w i t h i n a m a tu r e s t a n d o f skunkbush sumac
( Rhus t r i l o b a t a ) .
The t h i r d p l o t , r e p r e s e n t i n g a g r a s s l a n d h a b i t a t ,
was s i t u a t e d on a h i l l s i d e which had been c u l t i v a t e d a s r e c e n t l y as
th e 1920's.
The t h r e e p l o t s were t r a p p e d f o r small mammals d u r i n g f o u r
IO
summer p e r i o d s :
J u l y 11-29 and August 9 - 2 0 , 1975, and J u n e 21 -
J u l y 3 and August 19 -2 9, 1976.
A l i v e tra p p lo t co n siste d of a grid
o f 15 by 15 s t a t i o n s spa ced 15 m a p a r t , t h u s encompassing an a r e a o f
4 .4 1 h e c t a r e ' s .
One Sherman l i v e t r a p (8 x 8 x 23 cm) b a i t e d w ith
r o l l e d o a t s was p l a c e d w i t h i n 0 . 5 m o f each s t a t i o n .
A single tra p ­
p in g p e r i o d spanned s i x c o n s e c u t i v e n i g h t s .
Sander so n (1950) summarized n i n e d i f f e r e n t t r a p p i n g m e th o d o lo g i e s
i n an a t t e m p t t o d e t e r m i n e sample adequacy f o r a l o c a l small mammal
population.
S in c e t r a p method, ti m e o f sample and t y p e o f h a b i t a t
sampled a l l v a r i e d , and t r a p a v o i d a n c e v a r i e s among s p e c i e s , sample
adequacy v a r i e d from f o u r t o t e n o r more days t o c a p t u r e a s i g n i f i c a n t
number o f a l o c a l p o p u l a t i o n ,
M o r r i s (1955). found t h r e e n i g h t s were
r e q u i r e d t o c a p t u r e most o f a l o c a l p o p u l a t i o n o f d e e r mice.
Redman and S e a l a n d e r (1958) s t a t e d t h a t a minimum o f t h r e e ca p­
t u r e s o f an i n d i v i d u a l were r e q u i r e d t o c a l c u l a t e home r a n g e , and t h a t
no more th a n o n e - t h i r d o f t h e c a p t u r e s co u ld be on p e r i m e t e r
stations.
In t h e i r s t u d y , t r a p s were c l o s e d a f t e r t h e f i r s t c a p t u r e .
B l a i r (1942) and Tanaka (1953) f e l t t h a t more c a p t u r e s were n e c e s s a r y ;
however t h e y used r e p e a t e d c a p t u r e s i n t h e same t r a p i n t h e i r c a l c u ­
lations.
All s t a t i o n s on e i g h t a l t e r n a t e l i n e s o f t h e g r i d were t r a p p e d
f o r o n e - h a l f o f t h e p e r i o d and t h e r e m a in in g seven a l t e r n a t e l i n e s
the other h a lf;
The t r a p s were checked each morning and were r e b a i t e d
11
and r e s e t i f n e c e s s a r y .
Those a n i m a ls c a p t u r e d were marked by t o e ­
c l i p p i n g f o r i d e n t i f i c a t i o n and r e l e a s e d .
Each animal was i d e n t i f i e d
by s p e c i e s , number, s t a t i o n l o c a t i o n , s e x , age c l a s s ( a d u l t o r j u v e n i l e a c c o r d i n g t o s i z e and p e l a g e ) and e x t e r n a l r e p r o d u c t i v e c o n - '
dition.
D e n s i t y e s t i m a t e s o f d e e r mice were made f o l l o w i n g t h e method
d e s c r i b e d by B l a i r ( 1 9 4 1 ) , and home r a n g e s o f a l l a n i m a l s t r a p p e d
t h r e e o r more t i m e s i n one t r a p p i n g p e r i o d were c a l c u l a t e d by t h e
i n c l u s i v e boundary s t r i p method ( S t i c k e l , 1954).
Both d e n s i t y e s t i ­
mates and home r a n g e s were c a l c u l a t e d from c a p t u r e s made o n l y d u r i n g
sin g le six-day trapping periods.
Deer mouse d e n s i t i e s were a l s o
e s t i m a t e d from t h e J o l I y - S e b e r model ( S e b e r , 1973) u s i n g a computer
program d e r i v a t i o n ( S a u e r , 1979).
Computer a n a l y s i s ' and s t a t i s t i c a l
t e s t s were run t o c o r r e l a t e
f e a t u r e s o f t h e v e g e t a t i o n w it h t r a p p i n g s u c c e s s o f d e e r mice (Nie
e t a l . , 1975).
S c i e n t i f i c and common names o f mammals f o l l o w Hoffmann and
P a t t i e ( 1 96 8 ) .
S p e c i e s o f small mammals o f p o t e n t i a l s p e c i a l i n t e r e s t
f o l l o w F l a t h (1 9 7 7) .
RESULTSV e g e t a t i o n Types
S ix v e g e t a t i o n t y p e s were examined q u a n t i t a t i v e l y and q u a l i t a ­
t i v e l y on t h r e e l i v e t r a p g r i d s and a l o n g t h r e e snap t r a p l i n e s ( l i n e s
I , J and N i n F i g u r e I ) .
c l a s s f o r each t y p e .
T ab l e 2 p r e s e n t s mean p e r c e n t c o v e r by co v er
The mean p e r c e n t c o v e r f o r s hr u b and t r e e
s p e c i e s i s g i v e n in T a b l e ,3.
P e r c e n t f r e q u e n c y and mean c o ve r a ge rank
f o r dominant g r a m i n o i d , f o r b and s u b s h r u b s p e c i e s a r e g iv e n i n Table
4.
Ta b l e 18 (Appendix) l i s t s t h e f r e q u e n c y o f o c c u r r e n c e o f a l l
g r a m i n o i d , f o r b and s u b s h r u b t a x a found i n t h e s i x v e g e t a t i o n t y p e s .
Ponderosa P in e Type
The po n de ro sa p i n e t y p e o c c u r r e d on a l l a s p e c t s o f r i d g e s , s l o p e s
and d r a i n a g e b o tt om s .
soils.
I t was g e n e r a l l y found on loamy and s t o n y loam
S i z e c l a s s e s o f p i n e s were d i s t r i b u t e d in a mosaic p a t t e r n
t h r o u g h o u t t h e s t a n d sampled.
C o n s i d e r a b l e p i n e r e p r o d u c t i o n was
o c c u r r i n g w i t h i n t h e s t a n d as i n d i c a t e d i n F i g u r e 2.
The most mature
t r e e s a v e r a g e d 130 y e a r s o f age ( F i g u r e 3 ) .
The s t a n d sampled was r e p r e s e n t a t i v e o f t h e v a r i a t i o n in p in e
community t y p e s i n t h e s t u d y a r e a .
Ponderosa p i n e ( Pin us p o n d e r o s a )
a v e r a g e d 21 p e r c e n t c o v e r on t h e s t a n d .
v a rie d according to s i t e c h a r a c t e r i s t i c s .
Dominant u n d e r s t o r y s p e c i e s
Moist d r a i n a g e bottoms were
dominated by w e s t e r n snowberry ( Symphoricarpos o c c i d e n t a l i s ) ,
Kentucky b l u e g r a s s (Poa p r a t e n s i s ) and w e s t e r n w h e a t g r a s s ( Agropyron
TABLE 2 . —MEAN PERCENT COVER BY COVER CLASS FOR SIX VEGETATION TYPES AT SARPY CREEK, MONTANA,
1975-1976a
Cover C la ss
Bare Ground
Rock
L itter
Sumac
Grassland
1 7 .6
20.0
22 .3
7.0
0.5 -
1. 3
1.2
0.6
22.4
8.2
5.1
5. 3
6.8
9.0
.
61 .8
65 .3
7 3 .4
68.8
7 3. 8
9.2
7.3
14.3
2 4. 0
16. 0
0.9
1 4 .6
48.5
55.3
23.8
23.3
44.6
-
Forbs
13.6
Shrubs
21.4
20.2
Tree s
22.5
3.4
a
Deciduous
Shrub
Bottom
0.6
Lichens
Graminoids
. Riparian
Deciduous
Tree
Silver
Sagebr us h
Ponderosa
P in e
.
2
2
N = 225 4 m p l o t s f o r ea ch o f t h e f i r s t t h r e e t y p e s ; 40 tn p l o t s f o r each o f t h e l a s t
th re e types.
TABLE 3 . — MEAN PERCENT COVER FOR SHRUB AND TREE SPECIES FOR SIX VEGETATION TYPES AT SARPY
CREEK, MONTANA, 1975-1976
Species
Ponderosa
Pine
Sumac
Grassla nd
Silver
Sagebrush
Ta
1. 5
1 4 .4
1.0
1. 5
Ela eag nu s a n g u s t i f o l i a
T
Juniperus horizontal is
P in u s po n d ero sa
Prunus v i r g i n i a n a
Rhus t r i l o b a t a
T
19.3
Crataegus succulehta
J u n i p e r u s scopulbrum
Deciduous
Shrub
Bottom
17.3
Acer nequndo
A r t e m i s i a cana
Riparian
Deciduous
Tree
1.2
21.4
-
T
3.3
5, 0
T
1 3 .9
4.0
5.5
12.7
Ribes aureum
T
14.3
6.0
Rosa woodsi i
T
9.8
36.0
23.5
7.3
Sy mphoric arpos o c c i d e n t a l i s
4.2
aT r a c e i n d i c a t e s l e s s t h a n one p e r c e n t co v er
T
T
TABLE 4 . — PERCENT FREQUENCY OF OCCURRENCE/MEAN COVERAGE RANK FOR GRAMINOID, FORB AND SUB­
SHRUB SPECIES WHICH OCCURRED AT 20 PERCENT OR GREATER FREQUENCIES IN SIX VEGETATION TYPES
AT SARPY CREEK, MONTANA, 1975-19763
Species
Ponderosa
Pine
Sumac
Grassla n d
S ilver
Sagebrush
Riparian
Deciduous
Tree
Deciduous
Shrub
Bottom
90.0/1.2
40.0/2.0
GRAMINOIDS
Agropyron c r i s t a t u r n
74.2/2.4
Agropyron s m i t h i i
54.7/1.9
Agropyron s p ic at um
56.4/1.4
21.3/2.0
40.0/2.1
20.0/2.4
Andropogon s c o p a r i u s
20.0/1.3
A grostis p a l u s t r is
49.3/2.1
A ristid a longiseta
B o ut e lo u a
curtipendula
40.9/1.3
B o u te lo u a g r a c i l i s
Bromus j a p o n i c u s
32.0/3.3
25.3/1.8
30.0/1.8
42.2/2.8
50.0/2.8
8 8 . 4/ 1 .6
Bromus t e c t o r u m
Calamovilfa l o n g i f o l i a
37.8/2.6
Carex f i l i f o l i a
44,9/2.1
Elymus c i n e r e u s
K oeleria c r i s t a ta
37.5/3.2
30.0/2.0
43.1/3.0
22.5/2.3
TABLE 4 . — Continued
Ponderosa.
Pine
Sumac
Grass­
la n d
Poa p r a t e n s i s
12 . 0/ 2.1
26.2/2.6
Poa secunda
50.0/3.0
S t i p a comata
39.1/2/1
Species
Silver
Sagebrush
Riparian
Deciduous
Tr ee
Deciduous
• Shrub
Bottom
85.. 0 / 1 . 4
85/0/1.5
80.0/1.4
79.0/2.1
Stipa v irid u la
60.0/2.5
V ul pi a o c t o f l o r a
40.0/1.9
20.0/3.3
FORBS
A chillea m illefolium
24.9/2.8
Ambrosia p s i l o s t a c h y a
32.0/2.3
72.4/1.8
53.3/2.1
95.0/1.9
21 . 0/ 2.1
Artemisia dracunculus
Artemisia ludoviciana
22.5/2.9
28.0/2.4
40.0/2.1
29.3/1.7
27.5/1.6
Chenopodium album
Chrysopsis v i l l o s a
24.4/2.1
45.0/1.8
Cirs ium a r v e n s e
Eriogonum annuum
G utierrezia sarothrae
21.3/2.5
54.7/1.6
47.5/2.2
65.0/2.5
Medicago s a t i v a
Psoralea t e n u i f lo r a
35.0/1.4
TABLE 4 . — Continued
Species
R atibida columnifera
Tragopogon d u b iu s
Ponderosa
Pine
Sumac
Grass­
la nd
Silver
Sagebrush
Riparian
Deciduous
Tree
'2 0 .0 /2 .5
Deciduous
Shrub
Bottom
20.0/3.0
20.0/3.3
a Mean c o v e r a g e r a n k s were c a l c u l a t e d o n ly from t h o s e p l o t s on which a g iv e n s p e c i e s o c c u r r e d .
A lo w er r e l a t i v e r a n k i n d i c a t e s a r e l a t i v e l y h i g h e r canopy c o v e r a g e f o r t h a t s p e c i e s where
i t occurred
18
V)
260
O
200
6 -1 0
10-16
dbh
Fig. 2.
16-20 2 0 -2 6 2 6 - SO 3 0 -3 6
CLASSES (cm)
S i z e d i s t r i b u t i o n o f a l l ponderosa p in e t r e e s on
t h e po nde ro sa p i n e l i v e t r a p g r i d , Sarpy Creek,
Montana, 1976.
19
AGE
IN
YEARS
107.8
4 8 .0
15-20
20-25
25-30
30-35
dbh CLASSES (cm)
F ig . 3.
Age d i s t r i b u t i o n s o f te n po nd ero sa p in e t r e e s f o r each
f i v e c e n t i m e t e r dbh c l a s s .
Mean ag es a r e shown.
20
s m i t h i i ).
Skunkbush sumac ( Rhus t r i l o b a t e ) , bluebunch w h e a tg r a s s
( Agropyron s p i c a t u m ) and s i d e o a t s grama ( Bou teloua c u r t i p e n d u l a )
dominated d r i e r , sandy s i t e s o f s o u t h e r l y e x p o s u r e s .
M o i s t , sh ade d,
n o r t h - f a c i n g s l o p e s o f o t h e r p i n e s t a n d s o f t e n had s u b s t a n t i a l
c o v e r a g e o f c h o k e c h e r r y ( Prunus v i r g i n i a n a ).
P l a n t s p e c i e s d i v e r s i t y was h i g h e r i n t h e Ponderosa p i n e ty pe
th a n any o t h e r t y p e sampled.
L i t t e r c o v e r due to f a l l e n n e e d l e s was
s u b s t a n t i a l l y h i g h e r and g r a s s c o v e r was low er th a n f o r o t h e r vege­
t a t i o n t y p e s ( T ab l e 2 ) .
Skunkbush Sumac Type
Th is t y p e was found on sandy s i t e s , u s u a l l y o f s o u t h e r l y expo­
s u r e , where p i n e t r e e s d id n o t d o m in at e.
The sumac t y p e f r e q u e n t l y
formed a mosaic o f communities w i t h t h e g r a s s l a n d and s i l v e r sa g e­
b r u s h (A r t e m i s i a c a n a ) t y p e s .
The g r a s s l a n d t y p e o c c u r r e d where s i t e
c o n d i t i o n s d i d n o t a l l o w sumac to d o m in at e.
Where g ro u n d w a te r was
r e l a t i v e l y more a v a i l a b l e , t h e s i l v e r s a g e b r u s h t y p e dominated many
s i t e s t o p o g r a p h i c a l l y below s u m a c , s t a n d s , on h e a v i e r s i l t y s o i l s .
Skunkbush sumac dominated shr ub c o v e r on t h e s e s i t e s
(Tab le 3 ) .
I m p o r t a n t g ra m in o id c o n s t i t u e n t s o f t h e sumac ty p e i n c l u d e d p r a i r i e
sand r e e d g r a s s ( CalamoviI f a I o n g i f o l i a ) , t h r e a d - l e a v e d sedg e ( Carex
f i l i f o l i a ), p r a i r i e ju negrass ( K oeleria c r i s t a t a ), n a tiv e bluegrass
( Poa s e c u n d a ) and n e e d l e - a n d - t h r e a d ( S t i p a co m ata ).
A h ig h f r e q u e n c y
21
o f o c c u r r e n c e o f J a p a n e s e brome ( Bromus j a p o n i c u s ) and common ragweed
( Ambrosia p s i l o s t a c h y a ) a t t e s t e d t o p r i o r g r a z i n g s t r e s s by l i v e s t o c k .
G r a s s l a n d Type
The g r a s s l a n d s i t e i n v e s t i g a t e d was t h e g r a s s l a n d l i v e t r a p g r i d .
I t had been d i s t u r b e d by c u l t i v a t i o n a s r e c e n t l y as t h e 1 9 2 0 ' s , th u s
i t was n o t t y p i c a l o f n a t i v e g r a s s l a n d on t h e s tu d y a r e a .
Species
c o m p o s i t i o n o f n a t i v e g r a s s l a n d was com par abl e t o t h e g r am i n o id e l e ­
ments i n t h e u n d e r s t o r y o f t h e po n de ro sa p i n e and sumac v e g e t a t i o n
types.
The most s i g n i f i c a n t n a t i v e component found on t h e g r a s s l a n d g r i d
was t h e n e e d ! e - a n d - t h r e a d .
T h e , d i s t u r b e d n a t u r e o f t h e s i t e was
i n d i c a t e d by t h e predominance o f p l a n t e d and in v a d in g s p e c i e s ,
i n c l u d i n g c r e s t e d w h e a t g r a s s (Agropyron c r i s t a t u r n ) , c h e a t g r a s s ( Bromus
t e c t o r u m ) , r e d th r e e - a w n (A r i s t i d a l o n g i s e t a ) and f o r b s p e c i e s such as
common ragweed and annual buckwheat ( Eriogonum annuum).
S i l v e r S ag ebr us h Type
Thi s t y p e was found on broad sw a le s and o t h e r s i t e s where s u f ­
f i c i e n t s u r f a c e o r g r o u n d w a te r a l lo w ed growth o f s i l v e r s a g e b r u s h .
Grazing u t i l i z a t i o n o f t h i s and o t h e r r e l a t i v e l y m o i s t v e g e t a t i o n
t y p e s ( r i p a r i a n d e c i d u o u s t r e e and -deciduous s hr u b bottom t y p e s ) has
a l lo w ed i n v a s i o n by i n t r o d u c e d g r a m i n o id s and "weedy" f o r b s p e c i e s .
The dominant n a t i v e g r am in o id r em a in in g in t h e s i l v e r s a g e b r u s h ty pe
22
was g r e e n n e e d l e g r a s s ( S t i p a v i r i d u l a ) .
As i n o t h e r m o i s t s i t e t y p e s ,
Kentucky b l u e g r a s s was an i m p o r t a n t c o n s t i t u e n t o f t h e u n d e r s t o r y .
O th er ab u n d a n t s p e c i e s were J a p a n e s e brome, common ragweed, cudweed
s a g e w o r t (A r t e m i s i a l u d o v i c i a n a ) , and broom snakeweed . ( G u t i e r r e z i a
s a r o t h r a e ).
O v e r a ll gr am in o id c o v e r was h i g h e r in t h e s i l v e r sage
t y p e th a n a l l o t h e r s e x c e p t t h e d e c i d u o u s s hr u b bottom t y p e .
R i p a r i a n Deciduous T r e e Type
Th is t y p e was n a r r o w ly l i m i t e d t o m a jo r d r a i n a g e c h a n n e l s on t h e
study area .
B o x el de r (Acer negundo) was t h e p r i n c i p a l o v e r s t o r y
s p e c i e s w i t h 17 p e r c e n t c o v e r .
c o v e r were high in t h i s t y p e .
Shrub s p e c i e s d i v e r s i t y and canopy
I m p o r t a n t s h r u b s in o r d e r o f c o ve r a ge
were w e s t e r n s n ow be rry , golde n c u r r a n t ( Ribes aureum). Wood's r o s e
( Rosa w o o d s i i ) and c h o k e c h e r r y .
Western w h e a t g r a s s was an i m p o r t a n t
n a t i v e gram in oid a s w ell a s g i a n t w i l d r y e ( Elymus c i n e r e u s ).
Other
dominant g r a s s and f o r b s p e c i e s r e f l e c t e d d i s t u r b a n c e by l i v e s t o c k
and a d j a c e n t c u l t i v a t i o n .
These i n c l u d e d Kentucky b l u e g r a s s , a l f a l f a
(Medicago s a t i v a ) , Canada t h i s t l e ( C ir s iu m a r v e n s e ) and l a m b s q u a r t e r
( Chenopodiurn alb um) .
Deciduous Shrub Bottom Type
F l o r i s t i c a l l y s i m i l a r t o t h e p r e c e d i n g v e g e t a t i o n t y p e , t h i s ty pe
o c c u r r e d a l o n g t h e more mesic t r i b u t a r y d r a i n a g e s .
T a l l s hr u b ( s h o r t
t r e e ) c o v e r was dominated by hawthorn ( C r a t a e g u s s u c c u l e n t a ).
23
as well a s c h o k e c h e r r y and wild" plum ( Primus a m e r i c a n a ).
Lower s t o r y
s h r u b s i n c l u d e d Wood's r o s e , w e s t e r n snowberry and skunkbush sumac.
I m p o r t a n t n a t i v e m o i s t s i t e g r a m i n o id s were w e s t e r n w h e a tg r a s s
and g r e e n n e e d l e g r a s s .
Bluebunch w h e a t g r a s s was a l s o common owing to
proxim ity to d r i e r s i t e v e g etatio n ty pes.
Kentucky b l u e g r a s s was
a g a i n t h e dominant i n v a d i n g g r a s s , f o l l o w e d by J a p a n e s e brome.
Yarrow (A c h i l l e a m i l l e f o l i u m ) was an i m p o r t a n t f o r b .
T o t a l v e g e t a t i o n c o v e r was h i g h e s t in t h e r i p a r i a n d e ci du o u s t r e e
and d ec i d u o u s s h ru b bottom t y p e s due t o m o i s t s i t e c h a r a c t e r i s t i c s and
s t r a t i f i c a t i o n of vegetation.
Snap Tr a p p i n g Survey
A t o t a l o f 138 small mammals were t r a p p e d on snap t r a p l i n e s
d u r i n g 4500 t r a p n i g h t s .
Of t h e s e , t h e r e were 125 d e e r mice
( Peromyscus m a n i c u l a t u s ) , s i x common shrews ( Sorex c i n e r e u s ) , t h r e e
l e a s t chipmunks ( Eutamias minimus) , two meadow v o l e s ( M ic r o tu s
p e n n s y l v a n i c u s ) and one each o f Wyoming p o c k e t mouse ( P e r og n at hu s
f a s c i a t u s ) and n o r t h e r n p o c k e t gopher (Thomomys t a l p o i d e s ).
Table 5
g i v e s snap t r a p p i n g r e s u l t s f o r 1975 and 197.6.
S p e c i e s o t h e r th a n d e e r mice were c a u g h t o n ly in s p r i n g and sum­
mer when p o p u l a t i o n s were h ig h .
T ra p pi n g s u c c e s s o f common shrews was
a p p r o x i m a t e l y equal t o d e e r mice i n t h e r i p a r i a n d e c i d u o u s t r e e h a b i ­
t a t t y p e , p o s s i b l y i n d i c a t i n g high shrew d e n s i t i e s t h e r e f o r 1976.
TABLE 5 . — PERCENT SUCCESS OF SNAP TRAPPING SMALL MAMMALS, SARPY CREEK, MONTANA, 1975-1976
■ Vegetation Types
- Species
Riparian3
Deciduous Tree
■1976
Nb=360
Microtus pennsvlvanicus
’ 0.3 •
Peromyscus maniculatus
1.4
-Sorex cinereus
1.7
bN=total number of trap mgnts
Big Sage
19751976
N=180 N=360
Sumac
1975
1976
N=180 N=540 .
Ponderosa
Pine
1975
1976
N=540 N=900
0.6 -
0.4
Peroqnatnus fasciatus
anot trapped during 1975
Silver Sage
1975
1976
N=IBO N=360
'
Eutamias minimus
Tnomomys talpoides
Deciduous3
Snrub Bottom
1976
N=540
.
- 1.8
2.2
1.4
13.9
0.6
0.6
2.8
3.9
. 2.8 ■ 3.4
25
Meadow v o l e s a l m o s t s u r e l y o c c u r in t h i s h a b i t a t a l s o , as w el l as in
t h e c l o s e l y r e l a t e d d e ci d uo u s s h r u b bottom t y p e , b u t none were tr a p p e d
there.
Wyoming p o c k e t mice were found on o r n e a r where l o o s e , sandy
s u b s t r a t e a l lo w ed e x c a v a t i o n o f bu rr o w s.
L e a s t chipmunks were r a t h e r
n a r r o w ly l i m i t e d t o o r a t . t h e edge o f s t a n d s o f po n d ero sa p i n e .
Tne
b i g s a g e , s i l v e r sag e and sumac h a b i t a t s y i e l d e d o n ly d e e r mice t o
snap t r a p p i n g e x c e p t f o r one p o c k e t gop her .
P o p u l a t i o n s o f d e e r mice were h i g h e s t in l a t e summer and s p r i n g .
Low p o i n t s o c c u r r e d d u r i n g w i n t e r and midsummer ( T ab l e 6 ) .
Trends in
numbers c a u g h t th r o u g h t h e y e a r were s i m i l a r in a l l h a b i t a t s sampled.
B r eed in g se as on o f d p e r mice e x t e n d e d from a t l e a s t A p r i l throug h
August and p r o b a b l y c o n s i d e r a b l y l o n g e r , based upon t h e p r e s e n c e o f
j u v e n i l e s i n t h e p o p u l a t i o n in May, 1976, and t h e number o f a d u l t
fe m a le s i n r e p r o d u c t i v e c o n d i t i o n ( T a b l e 7 ) .
However, sample s i z e was
to o small l a t e r in t h e y e a r t o draw d e f i n i t i v e c o n c l u s i o n s .
There was
l i k e l y a peak i n b r e e d i n g ' i n s p r i n g , and s u b s e q u e n t l y s m a l l e r p e r c e n t ­
ages o f fe m a le s were b r e e d i n g a f t e r midsummer.
embryos f o r s i x p r e g n a n t fema les was 5 . 0 .
The mean number o f
The sex r a t i o o f a l l d e e r
mice c a p t u r e d i n snap t r a p s d u r i n g t h e s t u d y was 2.0 males p e r fema le.
The s ex r a t i o o f a d u l t mice c a p t u r e d was 2 . 6 males p e r f e m a le .
The
r e a s o n s f o r t h e d e v i a t i o n from t h e e x p e c t e d r a t i o o f 1:1 a r e unknown,
a l t h o u g h a l a r g e r home ran ge s i z e o f males and s e a s o n a l r e s t r i c t i o n s
o f f e m a le s t o n e s t d u r i n g p e r i o d s o f n u r s i n g o f t e n c o n t r i b u t e t o an
26
TABLE 6 . — POOLED DATA ON NUMBERS OF DEER MICE CAUGHT ALONG SNAP TRAP
LINES AND THE NUMBER OF DEER MICE PER IOO TRAP-NI GHTS OF EFFORT FOR
EACH TRAPPING PERIOD
Trap N ig h ts
Number
Deer Mice
Captured
Percent
Success
1080
49
4. 5
Fe br ua ry
540
3
0.6
May
900
36
4.0
July
1080
11
1.0
900
26
2. 9
T r app in g
P e r io d
1975
.
August
1976
September
o b s e r v e d se x r a t i o which s l i g h t l y f a v o r s males (Terman 9 1968).
Live Tr ap p i n g Survey
One hundred f i f t e e n i n d i v i d u a l d e e r mice were c a p t u r e d a t o t a l
o f 440 ti me s on t h e l i v e t r a p p l o t s .
In a d d i t i o n , 54 i n d i v i d u a l s o f '
seven o t h e r s p e c i e s o f smal l mammals were l i v e t r a p p e d a t o t a l o f 84
tim es.
Ta bl e 8 p r e s e n t s t h e numbers and s p e c i e s o f smal l mammals
c a p t u r e d on each o f t h e t h r e e l i v e t r a p g r i d s d u r i n g t h e f o u r
trapping periods.
The g r a s s l a n d g r i d s u p p o r t e d t h e g r e a t e s t d i v e r ­
s i t y o f smal l mammals, f o l l o w e d by t h e sumac g r i d .
However, th e
po nd ero sa p i n e g r i d s u p p o r t e d t h e d e n s e s t d e e r mouse p o p u l a t i o n and a
TABLE 7 , — POOLED DATA FROM ALL VEGETATIVE TYPES OF NUMBERS OF DEER MICE IN REPRODUCTIVE
CONDITION AND NUMBERS OF JUVENILES CAUGHT DURING EACH SNAP TRAPPING PERIOD
No. o f
Juveniles
T o t a l No.
o f Mice
Caught
5
m
CO
'd-
0
3
5
8
36
2 (3)
I
0
11
I (I)
0
2
26
A d u lt . M a le s i n
Reproductive
Condition
A d u lt Females i n
Reproductive
. Condition
August
6 (28)1
2 (IS)^
0
February
I (3)
0 ( 0)
0
May
14 (17)
6 ( 11 )
July
8 (8 )
19 (23)
Tr a p p i n g
Period
No. o f Females
w it h embryos
1975
September
.
^Number i n p a r e n t h e s e s i n d i c a t e s t o t a l number o f a d u l t males t r a p p e d .
p
3
Number i n p a r e n t h e s e s i n d i c a t e s t o t a l number o f a d u l t f e m a le s t r a p p e d .
T h i s number does n o t i n c l u d e one d e e r mouse whose sex co u ld n o t be d e t e r m in e d b ec a u se o f
consumption by s c a v e n g e r s .
TABLE 8 . — NUMBERS OF SMALL MAMMALS CAPTURED ON LIVE TRAP GRIDS BY TRAPPING PERIOD, SARPY CREEK,
MONTANA, 1975-1976
Species
G r a s s l a n d Grid
1975
1976
J u l y Auq. Ju n e Auq.
Sumac Grid
1976
1975
J u l y Auq. June Auq.
2
Eutamias
minimus
M ic r o tu s
pennsylvanicus
.I
8
7
9
I
I
Peroqnathus
fasciatus
Peromyscus
maniculatus
3
4
Sp erm op hi lus
tridecem lineatus
I
3
Tamiasciurus
h u d s o n ic u s
7
I
I
Onychomys
Teucoqaster
Sylvilaqus
audubonii
Ponderosa P in e Grid
1975
1976
J u l y Auq. J une Auq.
I
I
ro
CO
3
3
3
6
13
I
I
I
9
11
20
43 .
21
23
I
I -
29
r e l a t i v e l y dense p o p u l a t i o n o f l e a s t chipmunks.
T h i r t e e n - I i n e d ground s q u i r r e l s
'
(Spermophilus t r i d e c e m l i n e a t u s )
were common in t h e g r a s s l a n d h a b i t a t .
o n l y where t h e r e was dens e g r a s s c o v e r .
A few meadow v o l e s were ca ugh t
Wyoming p o c k e t mice were
c a u g h t on r e l a t i v e l y sandy s i t e s on t h e g r a s s l a n d and s h r u b l a n d g r i d s .
They were p r o b a b l y somewhat more a b u n d an t th a n t r a p p i n g s u c c e s s i n d i ­
cated.
Only one c o t t o n t a i l was c a u g h t on t h e g r a s s l a n d g r i d , s i n c e ,
t h i s s p e c i e s i s n o t r e a d i l y t r a p p e d by Sherman l i v e t r a p s .
Sim ilarly,
red s q u i r r e l s (T a m i a s c i u r u s h u d s o n ic u s ) were more ab u n d a n t tha n t h e
i n d i v i d u a l t r a p p e d on t h e woodland g r i d would i n d i c a t e .
Only one
g r a s s h o p p e r mouse (Onychomys l e u c o g a s t e r ) was caught, on the . g r a s s l a n d
g rid s in ce r o ll e d oats b a i t is not p a r t i c u l a r l y a t t r a c t i v e to t h i s
s p e c i e s and p r o b a b l y a l s o due t o low p o p u l a t i o n d e n s i t y i n t h e Sarpy
Creek a r e a .
T ab l e 9 g i v e s age and se x r a t i o s f o r l i v e - t r a p p e d d e e r mice.
The
se x r a t i o f o r a l l i n d i v i d u a l d e e r mice c a p t u r e d t h r o u g h o u t t h e s tu d y
period, on a l l t h r e e l i v e t r a p p l o t s was 1.7 males p e r f e m a le .
se x r a t i o o f a d u l t s was 1 . 8 males p e r f e m a l e .
The
Both a r e s i g n i f i c a n t
d e v i a t i o n s from t h e e x p e c t e d 1:1 r a t i o .
Home r a n g e s f o r some s p e c i e s o f s ma ll mammals a r e g iv e n in
Ta b le 10.
Home r a n g e s were c a l c u l a t e d from t h r e e o r more c a p t u r e s
w ith in a s in g le tra p p in g period to e l im i n a te in c lu sio n o f seasonal
s h i f t s in a c t i v i t y as p a r t o f t h e home r a n g e s .
Mean home r an g es of
TABLE 9 . —AGE AND SEX RATIOS OF DEER MICE FROM LIVE TRAP GRIDS, SARPY CREEK, MONTANA, 19751976
Trapping Period
1975
J u v e n i I e s a :IOO A d u lt s
M a l e s : 100 Females
.
July
32:100
262:100
August
36:100
140:100
J un e
50:100
173:100
August
54:100
162:100
1976
^including subadults.
TABLE 1 0 . — MEANS AND RANGES OF HOME RANGE SIZES IN HECTARES FOR DEER MICE ON THE THREE LIVE
TRAP GRIDS. HOME RANGES ARE CALCULATED FROM CAPTURES ONLY WITHIN EACH SINGLE 6-NIGHT
TRAPPING PERIOD
Gri d
Males
jN
Females
ha_
N
All I n d i v i d u a l s
ha
N
ha
Grassland
0 .5 7
I •
0 .5 7
0.39
3 ■
0 .3 9
June 1976
0
—
Aug. 1976
O
— ------ —
4
0.48
. J u l y 1975
Aug. 1975
.
'
3
O v e r a l l Means and
Ranges
Sumac
■
1.
4
.
0.48
(0.17 - 0.66)
O
-
J u l y 1975
4
0.21
Aug. 1975
5
0.32
4
J un e 1976
4
0.26 ,
Aug. 1976
4
17
O v e r a l l Means and
Ranges
4
'
0.21
9
0 .2 6
3
0.20
0.11
7
0.20
0 .4 1
2
0.25
6
0 .3 6
0.30
(0.07 - 0.69)
9
0.18
(0.07 - 0.38)
26
0 .2 6
TABLE 1 0 . --Continued
Grid
Females
Males
.
N-
ha
.
N
All I n d i v i d u a l s
ha
ha
N.
Ponderosa Pine
14
0.20
0.22
6
0.23
20
June 1976
5
0 .1 9
3
0.22
8
Aug. 1976
8
0.24
7
. 0.19 •
15
0.20
0.22
O v e r a l l Means and
Ranges
31
' 0.22
(0.07 - 0.50)
16
0.21
47
- 0.21
O v e r a l l Means from
All P l o t s
52
0.26
25
77
0.24
J u l y 1975
4
- Aug. 1975
•
0.20
0.22
4'
.
(0.05 - 0.61)
. . 0.20
d e e r mice were a p p r o x i m a t e l y a q u a r t e r o f a h e c t a r e in both t h e sumac
and pond ero sa p in e h a b i t a t s .
Home r a n g e s i n t h e g r a s s l a n d h a b i t a t .
were a b o u t t w i c e t h e s i z e o f t h o s e i n t h e o t h e r two p l o t s .
S tatisti­
c a l l y , t h e o n l y s i g n i f i c a n t d i f f e r e n c e between home r an ge s i z e s
sampled w i t h i n each s ex in t h e t h r e e h a b i t a t s was t h a t between males
i n g r a s s l a n d and p on de r o s a p i n e h a b i t a t s
rank t e s t ) .
(p < 0 . 2 , Mann and Whitney
Mean s i z e s o f male home r a n g e s were s l i g h t l y l a r g e r than
female home r a n g e s , a l t h o u g h t h e d i f f e r e n c e s were n o t s t a t i s t i c a l l y
significant.
A l a r g e amount o f i n d i v i d u a l v a r i a t i o n o c c u r r e d in s i z e s
o f home r a n g e s .
Only t h r e e home r a n g e s o f j u v e n i l e s , a l l i n sumac and
po nd ero sa p i n e h a b i t a t s c o u l d be c a l c u l a t e d , and t h e mean was 0 .1 9 ha.
One home ran ge o f an a d u l t female ground s q u i r r e l oh t h e g r a s s l a n d
p l o t was c a l c u l a t e d as 0 . 1 7 ha..
An a d u l t male Wyoming p o c k e t mouse on
t h e g r a s s l a n d p l o t had a home ran ge o f 0.11 ha, and two a d u l t male
chipmunks i n t h e p i n e p l o t had home r a n g e s o f 0 . 6 4 and 0 . 2 1 h e c t a r e s .
Ta b le 11 p r e s e n t s e s t i m a t e s of. p o p u l a t i o n d e n s i t y f o r some
s p e c i e s o f small mammals t r a p p e d on t h e t h r e e Sarpy Creek l i v e t r a p
g r i d s , c o r r e c t e d f o r e s t i m a t e d home r a n g e s i z e s .
D ensities, notably
i n c r e a s e d where t o t a l v e g e t a t i o n canopy co ver ag e i n c r e a s e d .
For p u r p o s es o f c o m pa r is o n, d e e r mouse d e n s i t i e s were a l s o e s t i ­
mated u s i n g a computer program o f t h e J o l l y - S e b e r model o f a n a l y s i s
( T ab l e 12 ) .
The two methods o f e s t i m a t i n g p o p u l a t i o n s produced very
s i m i l a r c a l c u l a t i o n s and i n d i c a t e d t h e same p o p u l a t i o n t r e n d s .
The
TABLE 1 1 . — ESTIMATES OF POPULATION DENSITY (INDIVIDUALS/HECTARE) FOR SOME SPECIES OF SMALL
MAMMALS ON THREE SARPY CREEK LIVE-TRAPPED HABITATS3
Species
Peromyscus
maniculatus
Grassland
1975
“1975
J u l y Aug. June Aug.
Sumac
1976
1975
J u l y Aug. J une Aug.
Ponderosa Pine
1975
1976
J u l y Aug. June Aug.
0.34
0.88
1.4 3
2.94
6 .2 3
3 .0 9
3.3 4
0.25
0 .8 7
0.99
0.87
1.12
0.51
1.81
Eutamias
minimus
1 .3 3
to
4
P e r o g n a th u s
fasciatus
Sper mop hi lus
tridecem lineatus
0.15
0.16
0.16
0.49
0.46
1 .0 6
0.46
0.4 9
0.46
0 .1 6
0 .4 6
Exce pt f o r P e r o m y s c u s , based on a s i n g l e e s t i m a t e o f home r a n g e s i z e f o r each s p e c i e s .
*
35
TABLE 1 2 . — POPULATION ESTIMATES (INDIVIDUALS/HECTARE) FOR DEER MICE IN
TWO SARPY CREEK VEGETATION TYPES USING JOLLY-SEBER MODEL OF ANALYSIS
T r ap pi ng
Period
Ponderosa
Pine
Sumac
J u l y , 1975
2.25
1.22
A u gu st, 1975
7 .9 4
2.04
• 3. 40
1.72
3 .6 6
1.66
J u n e , 1976
A u gu st, 1976
J o I l y - S e b e r model y i e l d e d a h i g h e r p o p u l a t i o n e s t i m a t e th a n d i d th e
home,range model in a l l cases' e x c e p t f o r t h e f i r s t t r a p p i n g p e r i o d f o r
t h e p o n d er o s a p i n e t y p e .
D e n s i t i e s f o r d e e r mice i n t h e g r a s s l a n d
t y p e and f o r o t h e r smal l mammal s p e c i e s i n a l l v e g e t a t i o n t y p e s co u ld
n o t be c a l c u l a t e d with, t h e J o l l y - S e b e r model due t o small sample s i z e .
C o r r e l a t i o n o f V e g e t a t i o n F e a t u r e s w i t h T r app in g Su ccess o f Deer Mice
V e g e t a t i o n d a t a was g a t h e r e d d u r i n g summer, 1975; hence c o r r e ­
l a t i o n w i t h t r a p p i n g d a t a was l i m i t e d t o t h e t h i r d and f o u r t h t r a p ­
p in g p e r i o d s .
S in c e no d e e r mice were t r a p p e d on t h e g r a s s l a n d g r i d
d u r i n g t h e s e p e r i o d s , c o r r e l a t i o n was f u r t h e r l i m i t e d t o t h e skunkbush sumac.and p on de r o s a p i n e l i v e t r a p g r i d s .
D i f f e r e n t s t a t i s t i c a l t e s t s were u t i l i z e d t o examine v a r i o u s
36
f e a t u r e s o f vegetatio n with r e s p e c t to the tra p p in g success of deer
mice.
F i r s t , t h e d a t a o f t r a p p i n g s u c c e s s f o r t h e sumac and pine
g r i d s were s u b m i t t e d t o b o t h s i m p l e r e g r e s s i o n and s t e p - w i s e m u l t i p l e
r e g r e s s i o n a n a l y s e s (Nie e t a l . ,
1975).
T ra p pi n g s u c c e s s was
r e g r e s s e d a g a i n s t p e r c e n t c o v e r by major v e g e t a t i o n c l a s s , i n c l u d i n g
t r e e s , s h r u b s , g r a s s e s , f o r b s , l i t t e r , b a r e ground and r o c k .
Addi­
t i o n a l l y , s im p l e and m u l t i p l e r e g r e s s i o n s were done f o r t h e s e v a r ­
i a b l e s combined as g r a s s e s , f o r b s and l i t t e r v e r s u s b a r e ground and
rock.
The l a t t e r t e s t was an e f f o r t t o examine t h e c o r r e l a t i o n
between t r a p p i n g s u c c e s s and o r g a n i c v e r s u s i n o r g a n i c m a t t e r f o r t h e
l o w e s t (gr oun d) s t r a t u m o f v e g e t a t i o n .
The F v a l u e s in e v e r y c a s e f o r b o th l i v e t r a p g r i d s y i e l d e d p
v a l u e s g r e a t e r th a n 0 . 0 5 , th u s no s i g n i f i c a n t c o r r e l a t i o n s co u ld be
established.
■ S u b s e q u e n t l y , s t e p - w i s e d i s c r i m i n a n t a n a l y s i s (Nie e t a l . ,
was performed on a l l v e g e t a t i o n s i t e s
two g r i d s .
1975)
( t r a p s t a t i o n s ) f o r each o f t h e
With a p o t e n t i a l maximum t r a p p i n g s u c c e s s o f s i x c a p t u r e s
p e r t r a p s i t e , d i s c r i m i n a n t a n a l y s i s was run u s in g t h e f o l l o w i n g
segregations:
All S i t e s C a t c h i n g :
A g a i n s t All S i t e s C a t c h i n g :
0 d e e r mice
0-1 d e e r mice
I o r more d e e r mice
2 o r more d e e r mice
0- 2 d e e r mice
3 o r more
d e e r mice
37
S i t e s c a t c h i n g 0 , I j 2 , 3, 4 o r 5 d e e r mice were run a g a i n s t each
o t h e r , th u s a l l p o s s i b l e p e r m u t a t i o n s were i n v e s t i g a t e d .
The v a r i ­
a b l e s examined were p e r c e n t c o v e r o f t h e major v e g e t a t i o n c l a s s e s in
one s e r i e s o f ru ns and p e r c e n t c o v e r o f s hr u b s p e c i e s i n a second
s e rie s of runs.
The c r i t e r i o n used t o d i s c r i m i n a t e was Rao1s V, a
g e n e r a l i z e d d i s t a n c e measure which a l l o w s f o r t h e g r e a t e s t o v e r a l l
s e p a r a tio n of groups.
The v a r i a b l e s used were n o t a b l e t o d i s c r i m i n a t e s i g n i f i c a n t l y
(P < 0 . 0 5 ) f o r t h e sumac l i v e t r a p g r i d .
S ig n ifican t discrim inating
power was a t t a i n e d f o r the. p i n e g r i d by v a r i a b l e s o f c e r t a i n major
v e g e t a t i o n c o v e r c l a s s e s and c e r t a i n s h r u b s p e c i e s .
The c a n o n i c a l c o r r e l a t i o n d e r i v e d from t h e comparison o f c a p t u r e
s i t e s w i t h n o n - c a p t u r e s i t e s i n d i c a t e d t h a t seven p e r c e n t o f th e
v a r i a n c e c o u l d be e x p l a i n e d by t r e e and b a r e ground c o v e r a g e s (p =
.0002).
Deer mice d i s p l a y e d an a f f i n i t y f o r b a r e ground and an
a v ersio n to pine cover.
Some s h r u b s p e c i e s y i e l d e d a s i g n i f i c a n t (p = 0 .0 2 4 ) b u t n o t
h i g h l y s e p a r a t e d d i s c r i m i n a t i o n between c a p t u r e and n o n - c a p t u r e t r a p
s t a t i o n s on t h e p i n e g r i d , bas ed on s h r u b canopy c o v e r a g e .
However,
r e s u l t s o f t h e s t a t i s t i c a l t e s t c o u l d n o t be c o n f i d e n t l y i n t e r p r e t e d
s i n c e t h e s e s h r u b s p e c i e s a l l o c c u r r e d a t such low f r e q u e n c i e s .
The f r e q u e n c y o f o c c u r r e n c e o f a l l g r a s s and f b r b s p e c i e s was
c a l c u l a t e d f o r v e g e t a t i o n p l o t s ( t r a p s t a t i o n s ) w it h c a p t u r e s o f d e e r
38
mice and f o r p l o t s w i t h no c a p t u r e s .
P l o t s w it h c a p t u r e s were t e s t e d
a g a i n s t p l o t s w i t h no c a p t u r e s by C h i - s q u a r e (Lund, 1978) f o r t h e
sumac and p i n e l i v e t r a p g r i d s .
S i g n i f i c a n t d i f f e r e n c e s i n o n ly a
few p l a n t s p e c i e s were seen between t h e two c l a s s e s o f p l o t s .
One s p e c i e s which d i s p l a y e d a p o s i t i v e c o r r e l a t i o n w i t h t r a p p i n g
s u c c e s s o f d e e r mice i n t h e sumac v e g e t a t i o n t y p e was t h r e a d - l e a v e d
sedg e (p = 0 . 0 1 9 ) .
S p e c i e s showing a n e g a t i v e c o r r e l a t i o n were
p r a i r i e j u n e g r a s s (p = 0 . 0 0 2 ) , t a r r a g o n s a g e w o r t ( A r t e m i s i a
d r a c u n c u l u s , p = 0 .0 4 3 ) and w h o r led milkweed ( A sc le p i as v e r t i c i l l a t a ,
p = 0.040).
For t h e pondierosa p i n e t y p e , s i g n i f i c a n t p o s i t i v e
c o r r e l a t i o n was d i s p l a y e d by common ragweed (p = 0 . 020 ) and n e g a t i v e
c o r r e l a t i o n by Kentucky b l u e g r a s s (p = 0 . 0 2 3 ) .
DISCUSSION
Live t r a p p i n g p e r m i t s r e c a p t u r e o f an i n d i v i d u a l , t h u s a l l o w i n g
a s s e s s m e n t o f home r an g e s i z e and, u l t i m a t e l y , c a l c u l a t i o n o f popu­
la tio n density.
S a r r a z i n and B id e r (1973) have revie we d s t u d i e s in an
e x a m i n a t i o n o f problems which a r e i n h e r e n t in th e use o f home range
estim ates to c a lc u la te population d e n s i t i e s J
home r a n g e s o v e r l a p ( W i l l i a m s , 1955).
One problem i s t h a t most
A second problem i s t h a t
i n d i v i d u a l s may e x t e n d t h e i r - a c t i v i t y o u t s i d e o f t h e t r a p p i n g a r e a
(Redman and S e a l a n d e r , 1958).
A nother d i f f i c u l t y a r i s e s i n t h a t t h e
s i z e o f home range, v a r i e s w i t h sex and a g e ; w it h s e a s o n and h a b i t a t
( S t i c k e l and Warbach, 1960); and i n v e r s e l y w i t h p o p u l a t i o n d e n s i t y
( S t i c k e l , 1960).
A f o u r t h problem i n u s i n g home range e s t i m a t e s t o
c a l c u l a t e p o p u l a t i o n d e n s i t i e s a r i s e s from t r a p shy i n d i v i d u a l s o r
s p e c i e s ( D i c e , 1931; Mohr, 1947; D a v is , 1953).
The f i n a l problem
a d d r e s s e d by S a r r a z i n and B i d e r (1973) was t h a t t r a p s p a c i n g can a l t e r
t h e a p p a r e n t s i z e o f home r an g e (Hayne, 1949 and 1950; M o r r i s , 1955;
F a u s t e t a l . , 1971).
Foll ow ing computer m od e li n g , O t i s , e t a l . (1978) s t a t e d t h a t in
t h e o r y , each t r a p p i n g g r i d s h o u ld i d e a l l y c o n s i s t o f 225 t o 400 l i v e
t r a p s a r r a n g e d i n a 15 x 15 o r 20 x 20 g r i d a t a 10 m o r 15 m t r a p
interval.
A minimum t r a p p i n g p e r i o d o f s i x c o n s e c u t i v e n i g h t s was
recommended.
40
Deer Mouse D i s t r i b u t i o n / V e g e t a t i o n C o r r e l a t i o n s
B l a i r (1942) f e l t t h a t v e g e t a t i o n a n a l y s i s would be i m p o r t a n t to
a s c e r t a i n why an animal a v o i d e d c e r t a i n t r a p s t a t i o n s w i t h i n i t s home
range.
Computer a n a l y s i s o f Sarpy Creek d a t a found l i t t l e s i g n i f i c a n t
c o r r e l a t i o n between t r a p p i n g s u c c e s s o f d e e r mice and v a r i o u s f e a t u r e s
of vegetation.
One problem a r i s e s i n t h e t y p e o f s t a t i s t i c a l
s e l e c t e d t o examine p o s s i b l e c o r r e l a t i o n s .
test
Multiple reg ressio n te s t s
were un ab le t o f i n d any s i g n i f i c a n t c o r r e l a t i o n s , w h i l e d i s c r i m i n a n t
a n a l y s i s found some.
The i n h e r e n t n a t u r e o f t h e r e g r e s s i o n t e s t was
un a b l e t o a c c e p t c a s e s where any v a r i a b l e was z e r o , and t h e d a t a bas e
f o l l o w i n g d e l e t i o n o f such c a s e s was to o small t o p e r m i t d i s c o v e r y o f
sig n ifican t correlations.
Since d is c r i m in a n t a n a l y s i s a ffo rd s
i n c l u s i o n o f such c a s e s , c o r r e l a t i o n s were found.
The l i m i t e d number
o f c o r r e l a t i o n s found i s p r o b a b l y a t t r i b u t a b l e t o e i t h e r t h e n a t u r e o f
t h e sy ste m t e s t e d o r t o f i e l d methodology.
In t h e f i r s t c a s e , i t may be t h a t t h e r e a r e few r e a l c o r r e l a t i o n s
t o be fo un d; o r t h a t t h e n a t u r e o f c o r r e l a t i o n s between t r a p p i n g s u c ­
c e s s and v e g e t a t i o n f e a t u r e s a r e so complexly r e l a t e d t h a t t h e y a r e
n o t e a s i l y d i s c o v e r e d W it h ou t a much l a r g e r d a t a b a s e .
Th is d a t a
ba s e may i n f a c t be n e c e s s a r i l y so l a r g e as t o p r e c l u d e t h e amount
o f f i e l d e f f o r t found in t h e m a j o r i t y o f small mammal s t u d i e s thus
f a r r e p o r t e d , a t l e a s t fo r those discu ssed in t h i s study.
In t h e second c a s e , t h a t o f methodology modeled f o r t h e f i e l d ,
41
any p a r a m e t e r s which a f f e c t t h e r e s u l t s o f small mammal o r v e g e t a t i o n
sampl ing may i n f l u e n c e e r r o r s in a s s e s s i n g c o r r e l a t i o n s .
For i n s t a n c e ,
t r a p p i n g s u c c e s s may be a f f e c t e d by many te mporal and s p a t i a l p a r a ­
m e te r s o t h e r th a n v e g e t a t i o n , such as animal m o b i l i t y .
Deer mouse
m o b i l i t y i s i n t u r n d e p e n d e n t on s p e c i e s - r e l a t e d , p h y s i o l o g i c and
demographic p a r a m e t e r s .
F u r t h e r m o r e , methods t o sample and d e f i n e
v e g e t a t i o n a r e t e m p o r a l l y as w ell as s p a t i a l l y d e p e n d e n t. ■ Thus, a
p
f o u r m p l o t used t o measure v e g e t a t i o n a t each t r a p s t a t i o n may be
i n a d e q u a t e t o d e t e r m i n e d e e r m o u s e / v e g e t a t i o n c o r r e l a t i o n s , due simply
t o t h e i n h e r e n t m o b i l i t y o f d e e r mice.
Th at i s , v e g e t a t i o n s p e c i e s
2
f r e q u e n c y o f o c c u r r e n c e o r canopy c o v e r a g e on a f o u r m p l o t may n o t
r e v e a l a n y t h i n g s i g n i f i c a n t a b o u t t h e o c c u r r e n c e o f d e e r mice a t t h a t
site.
The c o r r e l a t i o n s found by d i s c r i m i n a n t a n a l y s i s may t h e r e f o r e be
somewhat f o r t u i t o u s w i t h r e g a r d t o v e g e t a t i o n s p e c i e s f r e q u e n c y .
Few
g r a s s o r f o r b s p e c i e s o c c u r r e d on e i t h e r t h e sumac o r p i n e l i v e t r a p
g r i d a t s u f f i c i e n t l y h ig h f r e q u e n c y t o a l l o w a s i g n i f i c a n t t e s t o f
t h e i r c o r r e l a t i o n with tra p p in g success.
Of t h e s e , fe w er s t i l l
in dicated a s i g n i f i c a n t c o rre la tio n e i t h e r p o sitiv e or negative.
These r e m a in in g few p l a n t s p e c i e s a r e u l t i m a t e l y d i f f i c u l t t o e x p l a i n
i n terms o f t h e i r r e l a t i o n s h i p t o d e e r m ic e, a t l e a s t w i t h r e s p e c t t o
food p o t e n t i a l f o r s e e d - e a t i n g Pe romys cus.
Food p l a n t s p e c i e s may
n o t be a good i n d i c a t o r o f t r a p p i n g s u c c e s s o f small mammals on t h e
,
42
m i c r o s i t e b a s i s o f i n d i v i d u a l p l a n t s ( Co g s h al 1 , 1928 and Lo v e j o y ,
1975).
The p l a n t s p e c i e s i n v o l v e d i n t h e c o r r e l a t i o n s b e t t e r i n d i ­
c a t e o b s e r v e d t r a p p i n g s u c c e s s o f d e e r mice p r o b a b l y b ec a u se o f t h e i r
r e l a t i o n s h i p to various s o il f e a t u r e s , p a s t grazing or o th e r d i s ­
t u r b a n c e and t o p o g r a p h i c a l f e a t u r e s on a l o c a l b a s i s .
Canopy c o v e r co m par iso ns i n d i c a t e d t h a t t r a p p i n g s u c c e s s o f d e e r
mice oh t h e p i n e g r i d showed a p o s i t i v e c o r r e l a t i o n w i t h b a r e ground
and a n e g a t i v e c o r r e l a t i o n w i t h t r e e c o v e r , a l t h o u g h d e e r mice were
t r a p p e d more s u c c e s s f u l l y on t h e p i n e g r i d th a n on t h e ,sumac shrub
and g r a s s l a n d l i v e t r a p g r i d s .
Th is a g r e e s w i t h Pe ar so n (1959) and
S l y (1976) who found t h a t d e e r mice p r e f e r r e d i n t e r m e d i a t e s u c c e s s i o n a l s t a g e s w i t h o pen , woody v e g e t a t i o n .
Comparison o f R e s u l t s w i t h S i m i l a r S o u t h e a s t e r n Montana S t u d i e s
Owing t o a d r a m a t i c i n c r e a s e i n coal p r o d u c t i o n and e x p l o r a t i o n
i n s o u t h e a s t e r n Montana i n t h e 1 9 7 0 ' s , a number o f s t u d i e s have
r e c e n t l y i n v e s t i g a t e d small mammal, p o p u l a t i o n s t h r o u g h o u t t h e a r e a .
Such s t u d i e s have been con du ct ed f o r Peabody (ECON, 1975, 1976, 1977,
1978 a)... Decker ( P i t c h e r , 1977), P e a r l
(F arm er, 1977 and 1 9 7 8 ) , I n t a k e
(Swenson, 197 8) , P.M.' and Div ide in t h e Bull Mountains ( B er g er o n ,
1978 a & b ) , C o l s t r i p (ECON, 1978 b ) , Coal Creek ( B e r g e r o n , 1979),
Montco ( O l s o n - E l l i o t t and A s s o c i a t e s , 198 0) , O t t e r Creek and Hanging
Woman Creek ( M a r t i n , 1980a) and a t t h e Sweeney-Snyder, G r e e n l e a f - M i H e r ,
43
F o s t e r , Sand C ree k, B i r n e y , Kirby and Tongue R iv e r Dam s i t e s
(Martin,
1980b).
V a r i a b l e s w h ic h - ca n a f f e c t t r a p p i n g s u c c e s s were n o t c o n t r o l l e d
among t h e s t u d i e s r e v ie w e d , c o n s e q u e n t l y o n ly r e l a t i v e d e n s i t i e s o f
d e e r mice were examined f o r t h e p u r p o s es o f t h i s r e v ie w .
Dice (1938)
was u n c o m f o r t a b le w i t h u s in g t h e number o f an im als c a p t u r e d p e r t r a p
n i g h t as an in d e x o f abundance s i n c e a p p a r e n t d e n s i t i e s may d i f f e r
from t r u e d e n s i t i e s as a f u n c t i o n o f t r a p p i n g e f f o r t .
However, when
c o n s i d e r i n g many s t u d i e s o f d i f f e r e n t t r a p p i n g s t r a t e g i e s o v er s i x
y e a r s ' d u r a t i o n , r e l a t i v e d e n s i t i e s a l l o w an o b s e r v e r p e r h a p s t h e only
common b a s i s f o r comparison o f r e s u l t s .
T ab l e 13 compares r e l a t i v e d e n s i t i e s o f d e e r mice i n r e c e n t c o a l r e l a t e d s t u d i e s con du ct ed i n s o u t h e a s t e r n Montana.
In g e n e r a l ,
sm aller tra p p in g e f f o r t s incre ased the lik e lih o o d of apparent f l u c t u ­
a t i o n s from t r u e p o p u l a t i o n d e n s i t y .
T h e o r e t i c a l l y , t h e more t r a p
n i g h t s exp end ed , t h e g r e a t e r t h e p r o b a b i l i t y t h a t c a p t u r e r e s u l t s w i l l
r e f l e c t the t r u e population le v e l.
S t u d i e s from s o u t h e a s t e r n Montana
r e p r e s e n t e d s e v e r a l y e a r s ' e f f o r t ( 1 9 7 4 - 1 9 8 0 ) , and y e a r l y f l u c t u a t i o n s
s h o u l d be e x p e c t e d .
Although a l l s t u d i e s were in s o u t h e a s t e r n Montana,
s i t e d i f f e r e n c e s in d e e r mouse p o p u l a t i o n s can be e x p e c t e d , which may
also account fo r d i f f e r e n t capture r a te s .
A ls o , d e f i n i t i o n o f v a r i o u s
h a b i t a t s d i f f e r s c o n s i d e r a b l y from one s t u d y t o t h e n e x t .
The y e a r s o f t h e Sarpy Creek s t u d y (1975-1976) were r e l a t i v e l y
TABLE 1 3 . — COMPARISON OF RELATIVE DENSITIES OF DEER MICE AS DETERMINED BY THE NUMBER OF
CAPTURES PER IOO TRAP NIGHTS (LIVE AND/OR SNAP TRAPPING) IN SOUTHEASTERN MONTANA
H a b i t a t TypesaStudy
Woodland
Sarpy Creek (1975)
4 . 1 (.1890 ) b
Sarpy Creek (1976)
3. 1 (2610)
S hr u b la n d
Grassland
A griculture
Disturbed
2.8 (1980) 0 . 5 (1350)
0 (1350)
1.9 (2970)
Peabody (1975)
2 3. 0 (300)
Peabody ( 1 9 7 6 ) .
0.8
( 120) 2.2
(180)
Peabody (1977)
3.0
(.200) 2.0
( 200 )
4 . 0 (200)
Peabody (1978)
7.5
(400) 5 . 0
( 100)
2 3. 0 (200)
3.3
2.0
Decker (1976c )
2.9
P ea r l
(1977)
3.9
(600)
7 . 9 (1350) 2 . 4 ( 1200)
2.2
(75)
Pearl
(1978)
2.7
(450)
3 :0 (1350) 3 . 8 (1280)
1.3
(75)
I n t a k e (1977)
1.5
(840)
4 , 2 ( 1200) 2.1
1 . 4 (1200)
P.M. (1978)
1.3
(400)
2.7
D iv id e (1978)
C o l s t r i p (1978)
1.1 (2500)
5 . 0 ( 100)
Coal Creek (1979)
3.6
(190)
7.6
(720)
13.0 (2440) 8.0 (2440)
5.9
(720)
3 . 5 (2440) 2.6 (2440)
Montco (1978)
Montco (1979)
,
4.7
(720)
(150) 1.3 (1380)
.0.3
C/DO.)
8.0
(400) 5 . 0
( 100)
2.7
(780)
0.2
18. 3
(400)
2 3 . 0 (200)
TABLE 1 3 . - - C o n t i n u e d
H a b i t a t Types 3
Study
O t t e r Creek (1979)
Woodland
1.5 (1270)
Hanging Woman (1979) '
S h r u b la n d
Grassland
0.2
(490) 1.8
(450)
1.7,
(460) 0.2
(490)
Sweeney-Snyder (1980)
. 0 .4
(840)
0.5
(840)
Greenleaf-M iIler
(1980)
0.7
( 830)
0.1
(820)
F o s t e r (1980)
1.5.
( 810)
0.8
(800)
Sand Creek (1980)
(900)
0.7
( 880)
Bi rn ey (1980)
2.0
0.6
(810)
0.7
(760)
Kirby (1980)
2.0
(770)
2 .3
( 780)
Tongue R. Dam
(1980)
3 . 0 • (810)
2.6
(740)
Average
2.7
3.2
A griculture
Disturbed
■
2.0
(680)
4.2
2.0
2.0
18.3
.
18.3
a Woodland = c o n i f e r o u s a n d / o r d e c i d u o u s t r e e o v e r s t o r y ; Sh ru b lan d = ' mesop hy ti c s h r u b ! a n d
do mi n ate d by b i g s a g e b r u s h , s i l v e r s a g e b r u s h , skunkbush sumac, c h o k e c h e r r y / r o s e .
^Numbers in p a r e n t h e s e s i n d i c a t e t o t a l number o f t r a p n i g h t s .
c 8080 t o t a l t r a p n i g h t s f o r s t u d y .
46
m o i s t y e a r s , and e s t i m a t e d d e n s i t i e s were g e n e r a l l y h i g h e r th a n in
la te r years.
Sarpy Creek r e s u l t s i n ,1976 were c o n s i s t e n t l y lower tha n
in 1975, d e s p i t e an i n c r e a s e d t r a p p i n g e f f o r t in 1976.
Seasonal and
annual f l u c t u a t i o n s in small mammal p o p u l a t i o n s have been well docu­
mented (Myers and K r e b s , 1974). - In t h i s c a s e , t h e change c o u l d be
r e f l e c t e d in changes i n o n - s i t e v e g e t a t i o n co v er and s ee d p r o d u c t i o n ,
a major food s o u r c e f o r Perpmyscus m a n i c u l a t u s .
Also, s e v e r i t y of the
1975-1976 w i n t e r c o u l d have a f f e c t e d d e e r mouse p o p u l a t i o n s .
Although
a l l s t u d i e s were i n s o u t h e a s t e r n Montana, s i t e d i f f e r e n c e s i n d e e r
mouse p o p u l a t i o n s can be e x p e c t e d , whicn may a l s o a c c o u n t f o r d i f f e r ­
en t capture r a te s .
A l s o , d e f i n i t i o n o f v a r i o u s h a b i t a t s d i f f e r s con­
s i d e r a b l y from one s t u d y t o t h e n e x t .
Allowing f o r t h e above v a r i a b l e s , c a p t u r e r a t e s f o r woodland h a b i ­
t a t s ran ge d from 0 . 4 - 7 .6 p e r c e n t , w i t h an av e r a g e o f 2 . 7 p e r c e n t and a
median o f 2 . 0 p e r c e n t .
s l i g h t l y higher.
In c o m pa r is o n , Sarpy Creek r e s u l t s were
S i m i l a r l y , s h r u b l a n d d e e r mouse d e n s i t i e s v a r i e d
•from 0 . 1 - 1 3 . 0 p e r c e n t , a v e r a g i n g 3 . 2 p e r c e n t w it h a median o f 2 . 7 p e r ­
cent.
Sarpy Creek d e n s i t i e s were c o m p ar ab le .
D i f f e r e n c e s were
p r o b a b l y due t o wide v a r i e t y o f s h r u b l a n d h a b i t a t t y p e s and t h e wide
v a r ie ty of g r a s s / l i t t e r understory s p ecie s.
G r a s s l a n d h a b i t a t typ e s
y i e l d e d d e n s i t i e s which rang ed from 0 . 0 - 8 . 0 , a v e r a g i n g 2 . 4 p e r c e n t
w i t h a median o f 2 . 0 p e r c e n t .
Sarpy Creek d e n s i t i e s were low er.
/
The a v e r a g e d e n s i t y in s h r u b l a n d was g r e a t e r tha n i n woodland,
f o l l o w e d in o r d e r by g r a s s l a n d and a g r i c u l t u r e .
This r e f l e c t e d th e
47
d e c r e a s i n g d i v e r s i t y o f m i c r o s i t e h a b i t a t and th e h a b i t a t "edge
effect".
The 1975-1976 s t u d y con d uc te d a t Decker ( P i t c h e r , 1977)
derived s im ila r conclusions.
P i t c h e r [ 1 9 7 7 1 a l s o found i n t e r m e d i a t e
d i v e r s i t y , b u t t h e . h i g h e s t Peromyscus
d e n s i t i e s , in d i s t u r b e d h a b i ­
t a t f o r t h e Decker s t u d y .
Tabl e 13 i n d i c a t e s t h a t d i s t u r b e d t y p e s had g e n e r a l l y h i g h e r
d e n s i t i e s th a n a l l o t h e r h a b i t a t , t y p e s , i n d i c a t i n g t h e a b i l i t y o f
Peromyscus m a n i c u l a t u s t o s u c c e s s f u l l y r e i n v a d e a s i t e , t h a t i s , t o be
an " e a r l y s u c c e s s i o n " s p e c i e s .
Although r e c l a m a t i o n s i t e s a r e o f t e n
m o n o c u l t u r e , d e e r mouse d e n s i t i e s a r e h i g h e r th a n in g r a s s l a n d because
o f g r e a t e r seed p r o d u c t i o n in r e c l a m a t i o n , l a c k o f c o m p e t i t i o n from
g r a z i n g l i v e s t o c k , and a lower d i v e r s i t y o f o t h e r p o t e n t i a l l y compet­
i t i v e small mammal s p e c i e s .
O th er r e c e n t s o u t h e a s t e r n Montana s t u d i e s have made s i m i l a r o b s e r ­
vations.
ECON (1977) found d e e r mouse p o p u l a t i o n s in v a r i o u s n a t i v e
p l a n t communities were u s u a l l y low ( 1 . 2 - 2 . 4 / h a ) .
I t was th o u g h t t h a t
h i g h e r p o p u l a t i o n s were found in r e c e n t l y r e c l a im e d a r e a s , s i n c e new
v e g e t a t i o n growth a f f o r d e d ample c o v e r and food.
During r e p o p u l a t i o n ,
d e e r mouse numbers i n c r e a s e d r a p i d l y f o r a p e r i o d o f t i m e , th e n de­
c l i n e d t o n e a r normal l e v e l s .
However, d u r i n g dry y e a r s , d e e r mouse
numbers were low even on r e c l a i m e d a r e a s .
All s t u d i e s found t h a t d e e r
mice o c c u p i e d a w i d e r r an g e o f h a b i t a t s and were t r a p p e d i n g r e a t e r
numbers th a n o t h e r small mammal s p e c i e s .
ECON (1978 a) found much
48
h i g h e r d e e r mouse p o p u l a t i o n s in reclaimed, a r e a s tha n i n n a t i v e h a b i ­
t a t s f o r t h r e e s t u d i e s in s o u t h e a s t e r n Montana con d uc te d from 1973
th r o u g h 1978.
O th e r p a p e r s on Peromyscus e c o l o g y have r e p o r t e d t h e same d e e r
mouse a f f i n i t y f o r d i s t u r b e d s i t e s .
G as h w i le r (1959) i n v e s t i g a t e d th e
r e l a t i o n s h i p between n a t i v e t i m b e r h a b i t a t and newly logged a r e a s .
P h i l l i p s (1936) and Smith (1940) found t h a t d e e r mice e n j o y e d popu­
l a t i o n booms on o v e r g r a z e d s i t e s .
Jameson (1955) found d e e r mice were
t h e f i r s t small mammal s p e c i e s t o in v a de d i s t u r b e d s i t e s .
A comparison o f p o p u l a t i o n e s t i m a t e s o f d e e r mice f o r Sarpy Creek
and o t h e r n ear by s t u d i e s i s made i n T ab l e 14.
D i f f i c u l t i e s in com­
p a r i s o n o f t h e r e s u l t s o f t h e s t u d i e s l i s t e d a r i s e from d i f f e r e n t
m e t h o d o l o g i e s , sample s i z e s and t h e s e a s o n o f t r a p p i n g .
Sarpy Creek
d e n s i t i e s were g e n e r a l l y lower th a n t h o s e o f t h e o t h e r s t u d i e s shown
i n Ta b le 14.
D i f f e r e n c e s in t h e l o c a l i t i e s t r a p p e d a l s o c o n t r i b u t e
to d i f f e r e n t apparent d e n s i t i e s .
The Decker and P e a r l s t u d i e s , l e s s
th a n 10 m i l e s a p a r t , d i s p l a y e d r o u g h l y s i m i l a r d e n s i t i e s compared t o
Montco (60 m i l e s ) and Sarpy Creek (80 m i l e s ) .
S u b s t a n t i a l l y higher
d e n s i t i e s a t Montco were p r o b a b l y due m o s tl y t o se as o n o f t r a p p i n g
and l o c a l i t y .
Although n o t i n d i c a t e d i n Ta bl e 14, p o p u l a t i o n c h a r a c ­
t e r i s t i c s were g e n e r a l l y comparable among s t u d i e s , i . e . , males
g e n e r a l l y outnumbered f em a le s ( a t l e a s t i n l i k e l i h o o d o f c a p t u r e ) ,
p o p u l a t i o n s were g r e a t e s t in summer and autumn, and home r a n g e s o f
49
TABLE 1 4 . — COMPARISON OF DEER MICE DENSITIES ( I NDIVI DUALS/HECTARE) FOR
FOUR SOUTHEASTERN MONTANA STUDIES
'Vegetation
Type
Sarpy Creek
1975
1976
Decker 3
1976
Montco
1978
4.9
10.4
7. 7
12.2
4.0
Grassland
0.4 '
Sh ru bl an d
1. 3
1.4
3. 6
Woodland
4.6
3.2
3.5
Reclaimed Grassland
Pearlc
1978-79
3.0
81.3
a P i t c h e r (1977)
^ O l s o n - E l l i o t t and A s s o c i a t e s (1980)
c Farmer (1980)
males were l a r g e r th a n home r a n g e s o f f e m a l e s .
J
T ab l e 15 g i v e s t h e o c c u r r e n c e o f small mammal s p e c i e s by vege­
t a t i o n t y p e f o r t h e 19 s t u d i e s p r e s e n t e d in Ta bl e 13.
The d a t a
i n d i c a t e t h e w i d e s p r e a d o c c u r r e n c e o f Peromyscus m a n i c u l a t u s .
A less
th a n tho ro ug h e x a m i n a t i o n might c o n f u s e Mus musculus w i t h
Reithr odo nto my s m e g a l o t i s , a l t h o u g h Mus may be as w id e s p r e a d in s o u t h ­
e a s t e r n Montana as t h e d a t a in Tabl e 15 i n d i c a t e .
Most s p e c i e s were
t r a p p e d i n t h e h a b i t a t s e x p e c t e d (Hoffmann and P a t t i e , 1968).
G r a s s l a n d pr od uc es t h e g r e a t e s t d i v e r s i t y o f s p e c i e s , f o ll o w ed by
TABLE 15. NUMBER OF SOUTHEASTERN MONTANA STUDIES IN WHICH SPECIES OF SMALL MAMMALS WERE
RECORDED AS PRESENT IN COMMON VEGETATION TYPES. REFER TO TABLE 13 FOR A LISTING OF THE
19 STUDIES SURVEYED
Ri pari an
Deciduous
Tree
Na=S
Dipodomvs ordii
Eutamias minimus
Lagurus curtatus
Microtus ocnroqaster
Microtus pennsylvanicus
Musmusculus .
Neotoma cinereus
Onycnomvs IeUcoqaster
Peroqnatnus fasciatus
Peromvscus maniculatus
Reithrodontomvs meqalotis
Reitnrodontomys montanus
Sorex cinereus
Spermopnilus richardsoni
Spermopnilus
t r i decern!ineatus
Tamiasciurus hudsonicus
Tnomomys talpoides
Zapus nudsonius
I
I
’ I
2
I
Deciduous
Snrub
Bottom
N=2
Silver
Sage
N=6
I
I
I
I
2
I
Greasewood
N=I
I
I
Big .
Sage
N=IS
2
2
' 4
Sumac
N=S
I
Breaks
' N=3
2
2
2
3
2
2
I
I
I
3
2
6"
2
I
3
I
6
I ■
I
I
I
2
18
2
I
5
.
2
I
Grassland
N=12
3.
4
3
11
2
Ol
O
I
I
I
8
V
TABLE 1 5 . - - C o n t i n u e d
Species
Riparian
Grass
N=3
Ponderosa
Pine
N=17___
Agriculture
. N=5 '
Reclamation
N=3
Dipodomys ordii
Eutamias minimus
8
I
Lagurus curtatus
Microtus ochrogaster
2
I
Microtus pennsylvanicus
Mus musculus
I
I
3
■
I
•
I
Neotoma cinereus
Onychomys leucogaster
’2
I
Perognathus fa sc ia tu s
I
I
17
5
Peromyscus leucopus
Peromyscus maniculatus
Reithrddontomys megalotis
Reithrodontomys montanus
Sorex-cin ereu s'
3
2
3
I
I
3
2
I
3
I
Spermophilus richardsoni
Spermophilus
~tri deceml i neatus
Tamiasciurus hudsonicus
2
I
Thomomys talpoides
Zapus hudsonius.
aN = number o f stu d ies in which a given habitat type was investigated
I
t h e b i g s a g e b r u s h and r i p a r i a n dec id u o u s t r e e h a b i t a t t y p e s .
The
r i p a r i a n g r a s s t y p e has a low s p e c i e s d i v e r s i t y , p r o b a b l y due to
e x t e n s i v e g r a z i n g in t h i s t y p e and b e c a u s e o n ly t h r e e s t u d i e s sampled
t h i s h a b i t a t f o r small mammals.
I t a p p e a r s t h a t , in g e n e r a l , small
mammal d i v e r s i t y d e c r e a s e s as g r a s s c o v e r / l i t t e r d e c r e a s e s , al th o u g h
some h a b i t a t s d i s p l a y low d i v e r s i t i e s p a r t i a l l y due t o a low sample
effort.
P i t c h e r (1977) had r a t h e r d i f f e r e n t d i v e r s i t y r e s u l t s a t Decker.
Woodland h a b i t a t produced t h e g r e a t e s t d i v e r s i t y w i t h s i x g e n e r a ca p­
t u r e d i n x e r o p h y t i c s h r u b ! a n d s , and a g r i c u l t u r e and mine d i s t u r b a n c e
h a b i t a t s each had f o u r g e n e r a .
The l e a s t d i v e r s e h a b i t a t t y p e was
g r a s s l a n d , w i t h o n ly t h r e e g en er a c a p t u r e d .
Th is i s du e, in p a r t , t o
a r e l a t i v e l y s m a l l e r sampling e f f o r t in t h e g r a s s l a n d ty p e th a n o t h e r
t y p e s and b ec a u se lumping o f d i f f e r e n t h a b i t a t s i n t o a g e n e r a l h a b i t a t
t y p e ( e . g . s h r u b l a n d o r woodland) i n e f f e c t i n c r e a s e s h a b i t a t d i v e r ­
s i t y and t h u s , n i c h e d i v e r s i t y .
LITERATURE CITED
I
54
Bergeron, D.J.
1978a. T e r r e s t r i a l w i l d l i f e su rv ey f o r P-M Mine a r e a ,
Montana, 1977-1978. Tech. r e p . by Western Technology and
E n g i n e e r i n g , I n c . f o r P-M Mine Company.
100 pp.
_________ . 1978b. T e r r e s t r i a l w i l d l i f e s u r v e y f o r D iv id e Mine a r e a ,
Montana, 1977-1978. Tech r e p . by WESTEQH f o r Div ide Mine Company.
72 pp.
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I
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APPENDIX
f
60
TABLE 1 6 . — SPECIES LIST OF SMALL MAMMALS, SARPY CREEK, MONTANA
Insectivores
Sorex c i n e r e u s
S o r ex merriami
Sorex p r e b l e i
common shrew
M er r ia m s ' shrew
P r e b l e ' s shrew
X
*
*
Tong-eared b a t
l e a s t bat
l i t t l e brown b a t
long-eared bat
s ilv e r -h a ir e d bat
b i g brown b a t
ho ar y b a t
spotted bat
western big-ea red b at
X
w h ite -ta ile d jack r a b b it
mountain c o t t o n t a i l
desert cottontail
’
X
Bats
Myotis e v o t i s
Myotis l e i b i i
Myotis I u c i f u g u s
Myotis v o la n s
L a s i o n y c t e r i s n o c t i vagans
Eptesicus fuscus
Lasiurus cinereus
Euderma maculatum
P I e c o t u s to w n s en di i
Lagomorphs
Lepus to w ns en d ii
Sylvilagus n u t t a l l i i
S y l v i l a g u s au du bo ni i
X
Rodents
X
X
X
X
X
X
X
X X X X
porcupine
beaver
n o r t h e r n p o c k e t gopher
Wyoming p o c k e t mouse
. O r d ' s kangaroo r a t
l e a s t chipmunk
t h i r t e e n - l i n e d ground s q u i r r e l
red s q u ir r e l
house mouse
w e s t e r n h a r v e s t mouse
n o r t h e r n g r a s s h o p p e r mouse
d e e r mouse
m u s k r at
s a g e b r u s h v ole
p r a i r i e vole
meadow v o l e
‘
X
E r e t h i z o n dorsatum
Castor canadensis
Thomomys t a l p o i d e s
P e r o g n a th u s f a s c i a t u s
Dipodomys o r d i i
Eutamias minimus
, '
Sp erm ophilus t r i d e c e m l i n e a t u s
T a m i a s c i u r u s h u d s o n ic us
Mus muscuTus .
^
Reith ro don tom ys m e g a l o t i s
Onychomys l e u c o g a s t e r
Peromyscus m a n i c u l a t u s
Ond atra z i b e t h i c u s
Lagurus c u r t a t u s
M ic r ot us o c h r o g a s t e r
M ic r ot us p e n n s y l v a n i cus
X
61
TABLE 1 6 . — Continued
Rodents ( c o n t i n u e d )
M ic r o t u s l o n g i c a u d u s
l o n g - t a i l e d vole
X - S p e c i e s i d e n t i f i e d on Sarpy Creek s t u d y a r e a
* - S p e c i e s l i s t e d by F l a t h (1977) as b ei n g o f s p e c i a l i n t e r e s t
o r con ce rn
62
TABLE 1 7 . —SARPY CREEK PLANT SPECIES LIST
f
I
Pinatae
C yp r e s s a c e a e
Juniperus horizontal is
J u n i p e r u s scopulorum S ar g.
P in a c e a e
Pinus po n d ero sa Dougl.
L iliatae
Commelinaceae
T r a d e s c a n t i a b r a c t e a t a SmalI .
Cyperaceae
Carex f i l i f o l i a
Scirpus microcarpus P r e s l .
Iridaceae
Sisyrinchium a n g u s t i folium M ille r
Ju n c a c e a e
Junc us nodosus L.
L iliaceae
Alli um t e x t i l e N e l s . & Macbr.
Calochortus n u t t a l l i i T o r r .
F r i t i l l a r i a p u d ic a ( P ur sh ) S p r e n g .
Leucocrinum montanum
Smilacina s t e l l a t a (L.) Desf.
Yucca g l a u c a N u t t . .
Zygadenus venenosus S. Wats.
Poaceae
Agropyron c r i s t a t u m ( L . ) G a e r t n .
Agropyron s m i t h i i Rydb.
Agropyron s p ic a t u m ( P u r s h ) S c r i b n e r & Smith
A g r o s t i s p a l u s t r i s Huds.
Andropogon g e r a f d i Vitman
Andropogon s c o p a r i u s Michx.
A ristid a lo n g ise ta Steud.
Avena s a t i v a L.
B o ut e lo u a c u r t i p e n d u l a ( M i c h x . ) T o r r .
B o ut e lo u a g r a c i l i s ( H . B . K . ) Lag.
63
TABLE 1 7 . — Continued
■ Poaceae ( c o n t i n u e d )
Bromus j a p o n i c u s Thunb.
Bromus tec tor uf n L.
C a l a m o v i lf a l o n g i f o l i a (Hook) S c r i b n .
Elymus c i n e r e u s S c r i bn. & M e r r i l l
F e s t u c a i d a h o e n s i s Elmer
Hordeum d i s t i c h o n L.
Hordeum juba tum L.
Koeleria c r i s t a t a (L.) P e r s .
Muhlenberqia c u s p i d a t a ( T o r r . ) Rydb.
Mu hlenberqia racemosa -(Michx.) BSP.
O r y z o p s is hymenoides
Poa b u l b o s a L.
Poa p r a t e n s i s L. '
Poa secunda
Poa s p . ( I )
Poa s p . (2)
Phleum p r a t e n s e . L.
S i t a n i o n h y s t r i x ( N u t t . ) J . G . Smith
S p a r t i n a g r a c i l i s T r i n.
S t i p a comata T r i n. & R u p r .
S t i p a v i r i d u l a T r i n.
T r i t i c u m a e s t i v u m L.
Vulp ia o c t o f l o r a ( W a l t . ) Rydb.
M ag n o li at ae
Acera ce ae
Acer negundo L.
Anacardiaceae
Rhus r a d i c a n s L.
Rhus t r i I o b a t a N u t t .
,
Apiaceae
Lomatium macrocarpum (Hook. & A.) C.&R
Musineon d i v a r i c a t u m ( P ur sh ) R a f .
Asclepiadaceae
. -
A sclepias speciosa Torr.
■A s c l e p l a s s y r i a c a L.
A s c l e p i a s v e r t i c i l l a t a L.
64
TABLE 1 7 . — Continued
Asteraceae
A c h i l l e a m i l l e f o l i u m L.
Ambrosia p s i I o s t a c h y a DC.
A n t e n n a r i a m i c r o p h y l l a Rydb.
Arc tiu m la p pa L.
A r n ic a s o r o r i a Greene
A r t e m i s i a cana N u t t .
A r t e m i s i a d r a c u n c u l u s L.
A r t e m i s i a f r i g i d a Wi I I d .
A rtem isia ludoviciana Nutt.
, A rtemisia t r i d e n t a t a Nutt.
B al sa m o r hi za s a g i t t a t a (P u rsh ) N u tt .
C h r y s o p s i s v i l l o s a (P ur sh ) N u tt .
C ir s iu m a r v e n s e ( L . ) Scop.
C i r s i u m c a n o v i r e n s ( P yd b .) p e t r a k
■ C ir s iu m undulatum ( N u t t . ) S p r e n g .
C r e p i s o c c i d e n t a l i s N u tt .
E r i g e r o n d i v e r g e n s T.. & G
E r i g e r o n pumilus N u t t .
G a i l l a r d i a a r i s t a t a Pursh
G r i n d e l i a s q u a r r o s a ( P u r s h ) D un al.
G u t i e r r e z i a s a r o t h r a e ( P u r s h ) B. & R.
H e li a n t h u s annuus L.
H e li a n t h u s p e t i o l a r i s N u t t .
■ L ac tu ca s e r r i o l a L. '
L i a t r i s p u n c t a t a Hook. •
M i c r o s e r i s n u t a n s (Geyer) S ch.
R a t i b i d a c o l u m n i f e r a ( N u t t . ) Woot. & S t .
S e n e c i o . p i a t t e n s i s N u tt .
Solidago g iga ntea A it.
S o l i d a g o m i s s o u r i e n s i s N u tt .
Solidago m o llis B a r t l .
Taraxacum o f f i c i n a l e Weber
Tragopogon d ub iu s Scop.
Xanthium s tr um a ri um L.
Berberidaceae
B erb eris repens L i n d l .
Boraginaceae
, C r y p t h a n t h e c e l o s i o i d e s ( E a s tw . ) Pays.
Cynoglossum o f f i c i n a l e L.
Lithospermum in c is u m Lehm.
65
TABLE 1 7 . — Continued
Brassicaceae
Camelina m i c r o c a r p a A n d r z.
Erysimum inconspicuum (S. W a t s . ) MacM.
H e s p e r i s m a tr o na l i s L.
Sisymbrium a l t i s s i m u m ( L . ) B r i t t .
Stanleya p in n a ta (Pursh) B r i t t .
T h l a s p i a r v e n s e L.
C ac t a c e a e
M a m i l l a r i a m i s s o u r i e n s i s Sweet. '
Op un tia p o l y c a n t h a Haw.
Campanulaceae
Campanula r o t u n c l i f o l i a L.
C ap p a r i d a c e a e
Cleome s e r r u l a t a Pursh
C aprifoliaceae
Symphoricarpos o c c i d e n t a l i s Hook.
Caryophyl I a c e a e
C er as ti u m a r v e n s e L.
Chenopodiaceae
Chenopodium album L.
Kochia s c o p a r i a ( L . ) S c h r a d .
S a r c o b a t u s v e r m i c u l a t u s (Hook.) T o r r .
Con vol vu la cea e
Convolvulus a r v e n s i s L.
Convolvulus sepium L.
E l a ea g n ac ea e
El aea gn us a n g u s t i f o l i a L.
Eu ph o r b i a c e a e
Euphorbia g ly p t o sp e r m a Engelem.
Fabaceae
A s t r a g a l u s g i l v i f l o r u s S h e ld .
G l y c y r r h i z a l e p i d o t a ( N u t t . ) Pursh
Medicago l u p u l i n a L.
,
66
TABLE 1 7 . --Continued
Fabaceae ( c o n t i n u e d )
'
'
Medicago s a t i va L.
M e l i l o t u s o f f i c i n a l i s ( L . ) Lam.
O x y t r o p i s T a m b e r t i i Pursh
Oxytropis s e r i c e a Nutt.
P e ta lo s te m o n candidum Michx.
P e ta lo s te m o n purpureum ( V e n t . ) Rydb
P s o r a l e a a r g o p h y l l a Pursh
P s o r a l e a e s c u l e n t a Pursh
P s o r a l e a t e n u i f l o r a Pursh
Thermopsis r h o m b i f o l i a N u t t .
V i c i a am e r ic a n a Muhl.,
G rossulariaceae
Ribes aureum Pursh
H y d r o p h y ll a c e a e
P h a c e l i a l i n e a r i s ( P u r s h ) Holz
Lamiaceae
Mentha a r v e n s i s L.
Monarda f i . s t u l o s a L..
Li n ac ea e
Linum pe re n ne L.
Linum r i g i d u m
Malvaceae
S p h a e r a l c e a c o c c i n e a (P u rsh Rydb.
Onagraceae
Gaura c o c c i n e a Pursh
Oeno the ra a l b i c a u l i s Pursh
O en oth era s e r r u l a t a N u tt .
O ro branch aceae
’ Orobranche f a s c i c u l a t a N u tt .
P ap av er a ce ae
. Argemone i n t e r m e d i a Sweet
Plantaginaceae
Plantago patagonica J a c q .
1
TABLE 1 7 . — Continued
Polemoniaceae
Collomia l i n e a r i s N u t t .
Phlox h o o d ii Rich.
Polygalaceae
Polygala alba Nutt.
Polygonaceae
Eriogonum annuum N u t t .
Eriogonum flavum N u t t .
Eriogonum m u l t i ceps N ee s .
Rumex c r i s p u s L.
P r im u l a c e a e
Dodecatheon c o n ju g en s Greene
Ranunculaceae
D e l p h i n i urn b i c o l o r N u tt .
Ranunculus s c e l e r a t u s L.
Ranunculus g l a b e r r i m u s Hook.
Rosaceae
■ C r a t a e g u s s u c c u l e n t a S ch ra d.
F r a g a r i a v i r g i n i a n a Suchesne
Geum a l ep p ic um J a c q .
Geum t r i f l o r u m Pursh
Prunus a m er ic an a Marsh.
Prunus v i r g i n i a n a L.
Rosa a c i c u l a r i s L i n d l .
Rosa a r k a n s a n a P o r t e r
Rosa woodsi i L i n d l .
Rubiaceae
. Galium b o r e a l e L.
Salicaceae
Populus d e l t o i d e s Marsh
S a l i x e x i g u a N u tt .
Scrophulariaceae
Orthocarpus lu te u s
Penstemon a l b i d u s N u t t ;
TABLE 1 7 . — Continued
Scrophulariaceae (continued)
Penstemon s p .
Verbenaceae
Verbena b r a c t e a t a L. & R.
V io la c e a e
V io la c a n a d e n s i s L. ■
V io la n u t t a l l i i P u r s h .
TABLE 1 8 . — PERCENT FREQUENCY OF OCCURRENCE OF GRAMINOID,' FORB AND SUBSHRUB SPECIES FOR SIX
VEGETATION TYPES AT SARPY CREEK, MONTANA, 1975-1976
' Species
Ponderosa
Pine
GrassSumac ' • la nd
Silver
Sagebr us h
Riparian
Deciduous
Tree
Deciduous
Shrub
Bottom
GRAMINOIDS
Agropyron c r i s t a t u m
• Agropyron s m i t h i i
Agropyron s p i c a t u m
A grostis p a l u s t r i s
Andropogon g e r a r d i
Andropogon s c o p a r i us
A ristida longiseta
Bpiiteloua c u r t i p e n d u l a
Bout el ou a g r a c i l i s
Bromus j a p o n i c u s
Bromus t e c t o r u m
Calamovilfa l o n g i f o l i a
Carex f i l i f o l i a
Elymus c i n e r e u s
Festuca ida h o en sis
Hordeum ju b a tu m
Ju n cu s nodosus
Koeleria c r i s t a ta
M u h le n b er g i a^ race mosa
O r y z o p s is hymenoides
Poa p r a t e n s i s
Poa secunda'
75
I
55
56
21
2
16
8
3
90 ■
40
40
20
4
41.
7
32
5
9
I
20
2
50
15
5
27
42
.1
8
30
50
5
10
'
12
88
9
38
45
5
38
8
30
9
I
I
7
I
I
10
6
-
-
43
I
22
26
85
I
12
50
■ 85 ■
80
TABLE 1 8 . — Continued
Species
Ponderosa
Pine
Grass­
la nd
Sumac
Silver
Sage­
b ru s h
Riparian
Deciduous
Tree
Deciduous
Shrub
Bottom .
GRAMINOIDS ( c o n t )
Scirpus microcarpus
Sitanion h y strix
S t i p a comata
Stipa v irid u la
Triticum aestivum
Vulp ia octoTl o r a
.
I
12
I
73
39
10
60
9-.
I
5
10
20
5
22
40
FORBS
A chillea m illefolium
A lli u m t e x t i l e
Ambrosia p s i l o s t a c h y a
A n te n n ar i a mic r o p h y l I a
Ar ctium l a pp a
Argemone i n t e r m e d i a
A r n ic a s o r o r i a
Artem isia dracunculus
A rtemisia f r i g i d a
Artemisia ludoviciana
A sclepias sy ria c a
A sclepias v e r t i c i l l a t a
A stragalus g i l v if lo r u s
Ba ls a m o rh iz a s a g i t t a t a
B e r b i s r ep en s
15
24
I
32
8
I
72
53
10
95
2
'
8 .
I
14
5
'
11
28
4
I
4
6 .
2
8
21
.
'
4
29
15
9
8
18 -
2
2
-
I
5
40
2
•
18
5
12
'
TABLE 1 8 . --Continued
Species
Ponde ro sa
Pine
Sumac
Grassla n d
S ilver
Sagebr us h
Riparian
Deciduous
Tree
Deciduous
Shrub
Bottom
FORBS ( c o n t )
Calochortus n u t t a l l i i
Cameli n a m i c r o c a r p a
C e r a s ti u m a r v e n s e
Chenopodiurn album
Chrysopsis v i l l o s a
C ir s iu m a r v e n s e
C ir s iu m un dulatum
Coll omia l i n e a r i s
Crepis o c c i d e n ta lis
Cryptanthe c e l o s i o id e s
Cynogjossum o f f i c i n a l e
Erigeron divergens
Eriogonum annuum
Eriogonum m u l t i ceps
Euphorbi a g l y p t o s p e r m a
Fragaria v irg in ian a
Galium b o r e a l e
Glycyrrhiza le p id o ta
G rindelja squarrosa
Helianthus p e t i o l a r i s
H e s p e r i s m a tr o n a l i s
-Kochia s c o p a r i a
Lactuca s e r r i o l a
L i a t r i s punctata
I
I
4
3
'I
8
24
15
2
2
I
5
5
21
55
8
1
28
I
3
45
I
I
-I
I
2
I
I
I
3
3
5
5
2
8
I
11
I
. I
TABLE 1 8 . — Continued
Species
Ponderosa
Pine
Grassla nd
Sumac
Silver
Sagebru sh
Riparian
Deciduous
Tree
Deciduous
Shrub
Bottom
FORBS ( c o n t )
Linum peren ne .
• Litnospermum i n c i sum '
Medicaqo l u p u l i n a
Medicaqo s a t i v a
Mentha a r v e n s i s .
M icroseris nutans
Monarda f i s t u l o s a
Oxtropis la m b e rtii
P e ta lo s te m o n candidum
P e ta lo s te m o n purpureum
Phacelia l i n e a r i s
Phlox h o od ii
Plantaqo pataqonica
P s o r a l e a arq op h .y lla
Psoralea e scu le n ta
Psoralea t e n u i f l o r a
R atibida columnifera
Rumex c r i s p u s
Sisymbrium a l t i s s i m u m
Smilacina s t e l l a t a
Solidaqo m i s s o u r ie n s i s
S o li d a q o m o l l i s
Taraxacum o f f i c i n a l e
Ihlaspi arvense
8
-
I
I
8
•
10
-
65
I
2
I
6
I
9
■ 4
■ 5
.
I
3
4
2
I
2
12
■6 .
6
■5
12
35
5
I
20
20
I
8
2
8
18
3
3
I
.
'
I
5
I
I
I
' I
'
TABLE . 1 8. --Continued
Species
Ponderosa
Pine
Sumac
Grassla nd
FORBS ( c o n t )
Tradescantia b racteata
Tragopogoh dubi us
Verbena b r a c t e a t a
V i c i a am er ic an a
V io la c a n a d e n s i s
Yucca g l a u c a
SUBSHRUBS
2
9
I
X
I
2
L
I
7
2
2
.
G utierrezia sarothrae
O e n ot h er a s e r r u l a t a
12
I
3
I
'
Silver
■Sageb ru s h
Riparian
Deciduous
Tree
Deciduous
Shrub
Bottom
N?78
Sco93
cop.2
DATE
Scow, K. L.
Ecological d i s t r i b u t i o n
of small mammals at Sarny
Creek, Montana, with
special consideration ...
ISSUED
TO
^SSSSSmm,.
"N
, , S ji