A study of mink movements and populations on the lower Madison River, Montana
by James L Mitchell
A THESIS Submitted to the Graduate Faculty in partial fulfillment of the requirements for the degree
of Master of Science in Fish and Wildlife Management
Montana State University
© Copyright by James L Mitchell (1957)
Abstract:
A mink (Mustela vison energumenas) live-trapping study was conducted on the lower Madison River
near Three Forks, Montana, during various seasons of the year from 1955 to 1957, to determine
movements and populations. Live-trapped minks were marked in each ear with numbered strap type
tags. Fifteen of 42 tagged animals were live-trapped more than once. Different type traps and baits are
evaluated. One adult female's home range was determined by several captures at different trap sites.
Movements of other individuals are recorded. Only a small percentage of the area's total population of
minks was thought to have been live-trapped.
By use of the Lincoln Index, the total population of the area was calculated for two different years. The
adult female to juvenile ratio for the area was found to be lower than the statewide ratio. Average
weights of the live-trapped minks were determined and weight variations are discussed. A STUDY OF MINK MOVEMENTS AND POPULATIONS
ON THE LOMER MADISON RIVER, MONTANA
by
JAMES L. MITCHELL
A THESIS
Submitted t o the Graduate F a cu lty
.in
p a r t ia l f u lf illm e n t o f th e requirem ents
fo r th e degree o f
Master o f S cien ce in F ish and W ild life Management
at
Montana S ta te C ollege
Approved::
Bozeman, Montana
May, 1957 '
i1
- 2
—
TABLE OF CONTENTS
Page
A bstract .........................................................................................................................
3
In trod u ction ................................................................................................................
k
D e sc rip tio n o f
the area .........................................................................................
It
Methods ...........................................................................................................................
6
R e su lts ...........................................................................................................................
10
Trapping su c c e ss ............................................................................................
10
Movements
andhome ranges .........................................................................
11
Populations .......................................................................................................
15>
"Weights ................................................................................................................
17
Summary...........................................................................................................................
17
L itera tu re c ite d
19
-3 -
ABSTRACT
A mink (M ustela v iso n energomenas) liv e -tr a p p in g stu d y was conducted
on the low er Madison R iver near Three Forks, Montana, during variou s sea ­
sons o f the year from 1935 to 1 9 5 7 / to determine movements and popu­
l a t i o n s . L ive-trapped minks were marked in each ear w ith numbered strap
type t a g s . F ifte e n o f Jb2 tagged anim als were liv e -tr a p p e d more than once.
D iffe r e n t type trap s and b a it s are e v a lu a te d . One ad u lt fe m a le 's home
range was determ ined by s e v e r a l captures a t d if f e r e n t trap s i t e s . Move­
ments o f oth er in d iv id u a ls are recorded. Only a sm all percentage o f th e
a r e a 's t o t a l pop u lation of minks was thought t o have been liv e -tr a p p e d .
By use o f the L incoln Index, the t o t a l pop u lation o f the area was c a lcu ­
la t e d fo r two d if fe r e n t y e a r s . The a d u lt fem ale to ju v e n ile r a tio fo r
the area was found t o be low er than the sta tew id e r a t i o . Average w eights
o f th e liv e -tr a p p e d minks were determined, and w eight v a r ia tio n s are d is ­
cu ssed .
-IiHTRODUGTION
A mink (Must e l a v is o n energranenos) liv e -tr a p p in g program was con­
ducted on the low er Madison R iver hear Three Forks, Montana, during v a r i­
ous p eriod s from the f a l l o f 19# , to the spring o f 1# 7 , to ob tain in ­
form ation on movements, p op u lation s and other b io lo g ic a l f a c t o r s .
Ap­
p a r e n tly v ery l i t t l e s im ila r work has been done as a t t e s t e d by the p a u city
o f lit e r a t u r e on th e s u b je c t.
M arshall (1936) and McCabe ( 19)49) were able
t o d e lim it the approximate s iz e s o f home ranges o f female m inks, in c e r ­
t a in h a b ita ts and seasons in Michigan and W isconsin, r e s p e c t iv e ly .
Since
home range i s known to be in flu e n c e d by h a b ita t (B urt, 19I1O), i t seemed
d e sir a b le t o secure inform ation fo r t h i s l o c a l pop u lation which i s sub­
je c te d t o an annual h a rv est by commercial fo r tr a p p er s.
■The w r ite r w ishes to extend thanks to the Montana F ish and Game
■Department by whom he was employed during th e in v e s tig a tio n under P ro ject
W-It9-B and to Kenneth R. Greer o f th a t department fo r in t e r e s t and
guidance during the p r o je c t.
A lso , thanks are extended to th e landowners
in th e stu d y area and t o the commercial trapp ers who cooperated so w illin g ­
ly .
The w r ite r i s indebted to Dr. Don C. Quimby, Montana S ta te C o lle g e,
fo r h is d ir e c tio n o f the stu d y and a id in preparing the m anuscript.
DESCRIPTION OF THE AREA
The stu d y area i s a s ix m ile ( a ir lin e ) s e c tio n o f th e Madison R iver
extending from a p o in t s i x m iles south o f Three Forks to th e Highway 10
b r id g e , one m ile e a s t o f t h is c i t y (F ig . l ) .
W ithin the a rea , th e r iv e r
v a r ie s in w idth from. I4O yards in s in g le chann el, t o over 100 yards where
5
THREE
FORKS
RAY
CREEK
Fig. I .
A map of the study area
- 6
—
the course i s in terru p ted by numerous is la n d s .
than a fo o t in depth are common.
Shallow , ra p id areas l e s s
Depths o f over f iv e f e e t are r a re .
Severe gouging by ice-ja m s in w in ter forms new channels and o b lite r a te s
o ld ones w ith d eb ris or huge rock b a r s.
The current i s s w iftj the
grad ien t being 16 f e e t per m ile and the w aterflow i s kept alm ost constant
by a dam lo c a te d above th e area, ex cep t during sp rin g r u n o ff.
The main
channel c l o s e l y fo llo w s the w estern edge o f the v a lle y f l o o r .
'An i r r i ­
g a tio n can al and Ray Creek p a r a lle l the r iv e r to th e e a s t (F ig . l ) ’.
There i s no in flo w in g water from stream s.
The r ip a r ia n v e g e ta tio n c o n s is t s m ainly o f woody shrubs, w ith w illo w
(S a lix s p .) being the dominant ty p e.
Sparse to moderate cottonwood (Popu-
dns s p .) growths are a ls o found (F ig . 2 ) .
Hydrophytic v e g e ta tio n rep re­
sen ted m o stly by c a t t a i l s (Typha s p .) and b u llr u sh e s (Scirpus s p .) in
p r o te c ted areas and filam en tou s algae (Cladophera s p . ) , elsew h ere, i s
common.
METHODS
In th e summer and e a r ly f a l l , the e n tir e stud y area was tra v ersed
w ith a canoe-type b o a t.
Ic in g c o n d itio n s in w in ter made t h is type o f
tr a n sp o r ta tio n im p r a c tic a l, so a road was used along the top o f the dike
th a t p a r a lle ls the ir r ig a t io n ca n a l to the w e s t.
The presence o f mink s ig n near the w ater’s edge served as a b a s is fo r
p o s itio n in g tr a p s .
A. record o f trap lo c a tio n s was kept on a map o f th e
area prepared from a e r ia l photographs.
Only the e a s t sid e o f the r iv e r
and the ir r ig a t io n canal were trapped in w in te r .
Trap p o s itio n s were
Fig. 2.
A view of a section of the study area from the west side of the
Madison River.
The tip of an island is seen to the right.
changed fr e q u e n tly i f un productive.
S e ts were made under caved d ir t
banks, in rock r ip -r a p - w a lls , or on l e v e l ground and a l l were looselycovered w ith g r a s s , s t ic k s or so d .
C o lla p sib le m etal l i v e traps^produced
by the N a tio n a l Eive Trapping Company, Tomahawk, W isconsin were most
e ffe c tiv e .
T heyw ere o f two ty p e s .
Most su c ce ss was gained u sin g the
6" x 6" x 2li" double-door model s e t in runways w ith both doors open.
The
6" x 6n x 191V s in g le -d o o r type was. somewhat s u c c e s s fu l when placed as a
b lin d s e t in d ir t banks or rock w a lls .
A lso u sed , but w ith l i t t l e reward,
was a wooden tr e a d le -ty p e tr a p .
A v a r ie t y o f s c e n ts and lu r e s were employed.
Female s c a ts obtained
from l o c a l mink ranchers were app arently q u ite s u c c e s s fu l during the
breeding sea so n .
Musk glands procured from w ild mink c a r c a sse s during the
commercial trapping season were a ls o s u it a b le .
r e s u l t s , although many were t r ie d .
E dible b a it s produced poor
McCabe (l9 k 9 ) had most su ccess w ith
f r e s h ly k i l l e d r a b b it, whereas E itc e y (195%) obtained b e s t trapping
r e s u lt s when u sin g fr e sh f i s h .
A numbered f i s h stra p tag ( s i z e , 8 x 2 mm) w ith the in s c r ip tio n
M.F.G.D. (Montana F ish and Game Department) was p la c e d 'in each ear o f
trapped minks (F ig . U ).
They were q u ite s a t is f a c t o r y , fo r o n ly one known
lo s s o f a ta g by an anim al occurred, t h is on animal (E) w ith in a 388 day
p erio d .
Each anim al's v e n tr a l w hite sp ot p a tte rn was recorded as a d d itio n ­
a l a id in fu tu re id e n t if ic a t io n (McCabe, 191:9).
A c o lla p s ib le w ire cone (Newby e t a l , 1951:) made handling o f trapped
anim als by one man com paratively e a sy .
To the cone was attach ed a canvas
s le e v e th a t f i t t e d over the end o f the l i v e trap fo r convenient animal
9
f ■
^
Fig. 3. A mink in a single-door metal liv e -tra p .
.
The canvas sleeve that
is used for transfer to the cone and the cone i t s e l f are shown to
the righ t.
Fig. 4.
A mink with an identifying fingerlin g fish tag in i t s right ear
-1 0 tr a n s fe r (Fig* 3) .
Each animal was aged (ju v e n ile or a d u lt ) , sex ed ,
weighed (to n e a r e st 25> grams), examined for. in j u r ie s , and breeding s ta tu s
determined w h ile con fin ed in the cone.
Aging o f males Was accom plished by
p a lp a tio n o f the baculum (P e tr id e s , 19 5 0 ).
was more d i f f i c u l t .
Age determ ination o f fem ales
The presence o f gray h a ir s on the napes o f th e ir
necks was con sid ered c h a r a c t e r is tic o f a d u lts ( lo c a l trapp ers and mink
ranchers s a id t h is was due t o in ju r y o f th e t is s u e by the m ale's c la sp
during in t e r c o u r s e ).
Presence o f enlarged mammae made a d u lt i d e n t i f i ­
c a tio n p o s it iv e in summer and e a r ly f a l l , or as long as th e young were
s u c k lin g »
.
Commercial trap p ers were given maps fo r p lo t t in g p o s itio n s where th ey
captured tagged minks.
RESULTS
Trapping Success
A t o t a l o f 58UO trap n ig h ts (one trap s e t fo r 2h hou rs) captured 1*2
anim als 78 tim es (Table l ) .
captured.
F ifte e n anim als (3 5 .7 p ercen t) were r e ­
I t req u ired an average o f 7 1 .9 trap n ig h ts t o capture one mink.
The h ig h e s t trapp ing su ccess was recorded fo r f a l l , 1955| 25 .8 trap n ig h ts
per in d iv id u a l.
The b e s t su c c e ss in recap tu rin g tagged minks was r e a liz e d
during the w in te r .
2 1, 1957.
Four minks were captured from 23 trap u n its on March
Lowest su c ce ss was r e a liz e d in la t e summer.
to September 10t h , 1956, no minks were captu red.
From August 9 th ,
Sex and age c la s s o f
trapped anim als were; 21 ju v e n ile m ales, 10 ju v e n ile fe m a le s, fo u r adult
males and seven a d u lt fe m a le s.
-1 1 Four anim als d ied during the stu d y as a d ir e c t r e s u lt o f l i v e trap p in g.
Two succumbed in the traps due to c o ld , one from over-exh au stion
in hot weather and one from being squeezed by the door o f a wooden tra p .
Further deaths due to co ld were probably prevented by p la cin g c o tto n and
hay fo r bedding in a l l t r a p s .
Table I .
Season
1956
Summer
F a ll
1957
Winter
Spring
(To A pril 2It)
T otal
(A ll season s)
No. o f trap
n ig h ts
No. Captured
I n itia l
9
Repeat*
IA
CA
OM
C
1955
F a ll
Mink liv e -tr a p p in g su c ce ss by sea so n s.
7
13
0
I* *
926
3U8
12
I
I
3***
283
2218
58ItO
No. Recaptured
lx 2x 3x Ux 5x 6x 7x 8x
2
h2
I Tt
it
2
I
7
It
1
2
0
1
0
0
I
I
* Captured during a previou s season.
** Captured th ree tim es during t h is season and f iv e tim es during the
w inter o f 1957 (Mink - G, 9 t o t a l c a p tu r e s ).
-IHi-K- A ll th ree taken i n i t i a l l y in the w in te r , one having seven captures in
th a t season and one in t h is season (Mink - V ).
Movements and Home Ranges
Combining the liv e -tr a p p in g and commercial trapping data gave i n ­
d ic a tio n s o f d is ta n c e s tr a v e le d by tagged m inks.
Figure I shows lo c a tio n s
o f trap s i t e s fo r th o se animals captured in a t le a s t two d if f e r e n t tr a p s .
-1 2 Sex and age o f th ese minks are g iv en in Table IT.
The lo n g e s t d ista n c e between captures o f an in d iv id u a l (a ju v e n ile
male - F} , was 7 .9 m ile s , a i r l i n e , or l £ m iles by water and the in t e r v a l
between captures was 129 d ays.
This i s th e o n ly known mink to have l e f t
the stu d y area and i t probably moved along the water ro u te (F ig . l ) .
Of th e remaining 19 anim als, extreme movements o f 0 .2 (7 days) and
Iw8 (388 days) m iles between captures are in d ic a te d .
Data on one mink were s u f f i c i e n t fo r home range d eterm in ation .
The
trapping record o f ad u lt fem ale (G) in d ic a te d movement o f 0 .6 m ile s , once
in n in e days and once in one day.
From the i n i t i a l capture on the r iv e r
in August, 1996, t h is fem ale tr a v e le d 0 .2 m iles in 39 days from the r iv e r
to th e canal and then was taken four co n sec u tiv e tim es in the same trap in
ll|.9 d ays.
A fter March 3 , 1937> the animal was captured four tim es in
on the can al 0*3 m iles above and below the middle trap s i t e . Figure 3
shows an enlarged view o f th e trap s i t e s where t h is animal was captured '
and nearby trap s where she was not taken.
The minimum foragin g area, as
determined by connecting th e o u tsid e p o in ts o f capture and u sin g a p la n im eter to measure the e n c lo se d area, was 33*1 a c r e s .
The fem ales o f Mar­
s h a l l ’s (1936) stu d y r eg io n remained in an area o f approxim ately 20 acres*
McCabe.(19^ 9) rep orted th a t th e g r e a te s t d ista n ce fem ales moved in h is
stu d y area was I4OO yards.
lo n g er movements are in d ic a te d fo r ju v e n ile males than fo r oth ers
but the data are to o few fo r d e f in it e c o n c lu s io n s .
Movements between th e
canal and th e r iv e r were more common than movements r e s t r ic t e d t o e ith e r
Table TI.
Number o f c a p tu res, days between ca p tu res, d ista n ce tr a v e le d , and
w eight changes o f tagged minks.
Age
Sex
Captures
Days
between
captures
A
TH
C
D
E
F
G
J*
J
J
J
J
J
A
F
F
M
M
M
M
F
2
n r
H
J
K
L
M
N
R
S
T
D
V
J
J
J
J
A
J
A
J
J
A
J
J
M
F
F
M
F
M
M
M
M
F
M
M
W
J
M
Mink
P
2-s-s
2 -s*
2
2**
2-s-x9
3
3
3
3-ss
2
2
"TT
3
2
fi
2
2-s-ss
D istance
tr a v e led
between
captures
(A ir lin e m iles)
0
0.3
1.7
7
388
0 .2
h .8
129
59, U , 12, 112,
111, li, I ,
9
7.9
0 . 2, 0 , 0, 0 ,
0 , 0 . 3 , 0 . 6 , 0 .6
0, 0
" i, 5
0, 0
________ ^ 7 ________
6, U
0, 0
0 , 0 .6
h , 17
0
nr
i
0
6 , 1 3 ,n r "
ii, i
i&
17, 3, 3
Ti
Ij 1» I ,
I , h,
L
21
0, 0, 0.3
0 .3 , 0.3
0
0, 0, 0.3
0.3
0, 0, 0 . 3 , 0 .8
Weight
(Grams)
I n itia l
Changes
5oo
-25
795
1100
85o
750
625
1025
" 55o
“ 6oo
“ 875
600
1225
1300
1000
1360
700
1350
1250
0 . 8, 0 , 0
o.f.
?
~T~
525
1325
-5o
?
?
-25, +25, +25, +50
-25, -25, -25, -5o
' -100, r r
+100,
0
~ + 75, -2 5 ~
- 25, ?
f 2F ~
' -75
~ +5o, 0, -200
0, 0
-HO
-5o, -50, -50
0
-75, +50, +25
-75, -50, +50, +50
------ — z
- S - J - J u v en ile; A - A dult.
-**- Mink trapped in commercial trapping season (Nov. 10 - Dec. 31 o f each y e a r ),
-sss Mink taken by commercial beaver trapper in A p r il, 1957.
-
--------
14
LEGEND
0
1
® - TRAPS
WHERE
X - OTHER
TRAP
------ MINIMUM
Fig. 5.
SIZE
Iyf2 MILE
I
I
MINK
IGJ
WAS
CAPTURED
LOCATIONS
OF
MINK
(G 'l)
HOME
RANGE
An enlarged section of Fig. I showing the minimum home range of
mink (G).
;th e can al or the r i v e r .
. P opulations
D ice ( l 9 3 l ) , Burt (l9 ltb )? B la ir ( IPltO) } Evans ( l 9i;2 ) and oth ers used
liv e -tr a p p in g data t o c a lc u la te p op u lation s o f variou s ty p es o f ro d en ts.
The assumption was th a t a ll- animals on the area had been captured.
The liv e -tr a p p in g data o f the p resen t stu d y do n o t in d ic a te th a t a l l
minks - on the area were caught5 u n le ss the p op u lation s were h ig h ly u n sta b le ,
which may be su ggested by the behavior o f mink (F ), p r e v io u s ly d isc u sse d .
Thus, none o f nin e minks caught in the f a l l o f 1935 were captured in th e
summer o f 1956, but two were taken com m ercially the same f a l l as marked.
Only one o f seven summer-trapped animals was caught the fo llo w in g f a l l .
S im ila r data fo r oth er seasons are in d ica ted , in Table I .
On the other
hand, the long movement o f mink (F) i s more l o g i c a l l y exp lain ed by th e
p resence o f a s ta b le p o p u la tio n , and in t r a s p e c if ic s t r i f e (E rrin gton,
19lt3) forced t h i s ju v e n ile t o lea v e the a rea .
I n a b il it y to recapture
tagged minks between season s would th en 'b e ex p ected .
The data are
app arently to o few fo r p op u latio n c a lc u la tio n by the above method.
An estim a te o f the p op u lation was provided by use o f th e L incoln
Index,
Nine anim als were tagged on the area p revious to th e 1955 commer­
c i a l trapping sea so n .
Two were taken during th a t sea so n .
v id u a ls were tagged in 1956.
Seventeen in d i­
Thus, th ere 'was a p o t e n tia l o f 2lt marked
anim als on th e area during the 1956 commercial trapping sea so n .
s te e l-tr a p p e d .
Three were
The 1 9 5 5 -population was c a lc u la te d to be /<2jminks ( 9 ;X as
2:23) w ith 2 S 6 (2U:x as 3:32) in 1956.
There were approxim ately 12.75
-id s e c tio n s in the stu d y area, g iv in g 8*1 minks per s e c t io n , or 3 ,5 fem ales
per s e c tio n in 1 9 & .
M arshall (1936) estim a ted 1 .5 fem ales per s e c tio n
a ft e r a heavy trapping season*
Bi 1955 th e t o t a l number (2 3 ), age, and sex o f a l l known animals
taken com m ercially o f f th e stu d y area were a v a ila b le , but in 1956, only
th e t o t a l number (32) taken was o b ta in ed .
Table I I I shows sex and ages
o f th e animals taken o f f the area by liv e -tr a p p in g during th e e n tir e
stud y; th ose taken o f f the area by commercial trapp ers in 1955, and a
sample o f 985 o f the minks taken during th e 1955 sta tew id e trapping
sea so n .
The sta te w id e r a t io 1 :5 .2 (G reer, 195?) o f ad u lt fem ales to
ju v e n ile s i s somewhat high er than the liv e -tr a p p in g r a t io ( l i l u l i ) and
commercial trap p in g r a t io ( 1 : 3 .8 ) fo r the area*
This in d ic a te s th a t the
rep rod uction may n o t be maximum oh th e area and ah in crea sed h a rv est might
be a d v isa b le .
Table I I I .
Ages and sex es o f mink liv e -tr a p p e d and Commercially ■
trapped oh the study area and a sample o f 985 minks
taken sta te w id e .
P eriod
L ive-trap p in g
(1955-57)
Commercial Trapping
•- oh th e Area (1955)
.Commercial Trapping;
Statew ide (1955)
Adults
J u v e n iles
Male
Female
h
7
h
" It
136
137
Male
'
. Female
' 21
10
12
3
138
2 Th
-1 7 '.Weights
W eights o f four a d u lt males averaged 12li5 grams, ranging from 1100 to
ll^OO grams.
W eights o f seven ad u lt fem ales averaged 5>60 grams, ranging
from 275 t o 700 grams.
McCabe (l9 li9 ) rep o rts the m id minks he captured
in W isconsin to average as fo llo w s s
fem a les, !?7h grams.
adu lt m a les, 10J?5> grams $ ad u lt
In th e p resen t stu d y, the fem ale w eigh ts averaged li5>
percent o f th e m ales.
Examination o f Table I I in d ic a te s no apparent c o r r e la tio n between
d ista n c e s tr a v e le d , days between captures and w eight lo s s e s o f tagged
minks.
The extremes showed a gain o f 100 grams in s i x days between cap­
tu r e s w ith no apparent movement and a lo s s o f 200 grams w h ile tr a v e lin g
0 ,3 m ile s .
The former was a female and the l a t t e r a m ale, but no co rre­
la t io n i s found between th e sex e s on w eight v a r ia tio n s w ith r e s p e c t to
number o f captures and days between c a p tu res.
lo s s e s were both by m ales.
The two la r g e r w eight
Even during th e breeding sea so n , th ere was no
g e n e ra l trend o f w eight l o s s e s , by males or fem a les.
SUMMARY
1.
A stu d y o f minks w ith emphasis on movements and p op u lation s was
conducted on a s e c tio n o f th e low er Madison R iver th a t extends from a
p o in t s i x ( a ir lin e ) m iles south o f Three Forks, Montana, to the Highway 10
b r id g e , one m ile e a s t o f t h is c i t y , during the f a l l o f 1953, summer and
f a l l o f 1956, and the w in ter and p art o f th e spring o f 1957.
2.
Numerous is la n d s dot the s w ift-flo w in g r iv e r chann el, so th a t
water su rface w idths vary from ItO to 100 yards w ith in the a rea .
Depths
under one f o o t i-jere cominon and over f i v e f e e t ^ r a r e .
Hfoody shrubs}
rep resen ted m ainly by w illo w was the predominate r ip a r ia n v e g e ta tio n , w ith
a sparse to moderate cover o f cottonwood.
Submerged, f lo a t in g and emergent
aq u atics were common...
3.
A ccess to the area fo r liv e -tr a p p in g was gained by Using a boat
in summer and f a l l and a nearby road in w in te r .
M etal, two-door l i v e -
tr a p s w ith e it h e r mink s c a t s or musk as sce n t were most s u c c e s s fu l in
capturing minks.
Trapped animals were handled w ith the use of. a s p e c ia lly
made w ire con e.
•
Forty-tw o animals were captured 78 tim e s5 13 were recaptured.
E leven a d u lts and 31 ju v e n ile s were tak en .
Age o f l i v e - trapped males was
determ ined by p a lp a tio n o f th e baculurm ^ Adult fem ales were recognized by
presence o f w e ll-d e v e lo p e d mammae a id gray h a ir s on th e napes o f t h e ir
n eck s.
Trapping su c ce ss was b e s t in la t e f a l l and w in te r , p o o rest during
th e l a t e summer.
3.
Ju ven ile, m ales were in d ic a te d t o have moved the g r e a te s t d ista n c e s
during, th e study,* one moving 7 .9 a ir lin e m ile s , and another Iu 8 .
One fem­
a le showed a home range o f 3 3 .1 a c r e s .
6.
The t o t a l p op u lation o f the area was estim a ted t o be 9b mink in
1933 and 232 in 1936 by u se o f the' E incoln Index.
The a d u lt female to
ju v e n ile r a t io s o f I iIu ll and 1 :3 .8 as determ ined from liv e - t r a p captures
and commercial trapping d a ta , r e s p e c t iv e ly , were lower than th e 1 :3>2
sta tew id e r a t i o .
7.
L ive-trapped adult males averaged 12li3 (llOO-lliOO) grams and
a d u lt fem ales 360 (273-700) grams.
No apparent c o r r e la tio n was found
-1 9 b etween d ista n c e s tr a v e le d , days between captu res and w eight v a r ia tio n s o f
m inks.
EITERATURE CITED
B la ir , ¥ . Frank, 19lt0. Home ranges and p o p u la tio n s o f the meadow mouse
in Southern M ichigan. Jour. W ild l. M gt., U ( 2 ) : llt 9 - l6 l.
B urt, W illiam H ., I 9I4O. T e r r ito r ia l behavior and p op u lation s o f some
sm all mammals in Southern M ichigan. M isc„ p u bl. - Museum o f Z o o l.,
Hniv. o f M ich ., No.
^8 pp.
D ic e , Lee R ., 1931. Methods o f in d ic a tin g the abundance o f mammals.
Jour. Mamm., 12(U)$376-381.
E rrin gton , Paul L ., 19U3. An a n a ly s is o f mink predation upon muskrats in
N orth-C entral U nited S t a t e s . Iowa Agr. Exp. S t a ., R es. B u ll. 320;
79U-92U.
Evans, F . C ., 19U-2. S tu d ies o f a sm all mammal pop u lation in B agley Wood,
B erk sh ire. Jour, o f Anim. E c © l.,ll(2 );l8 2 -1 9 7 .
Greer, Kenneth R ., 1957- Completion R eport, Montana F ish and Game, Fur
R esources Surveys and I n v e s tig a tio n s .
M arshall, W illiam H ., 1936. A stu d y o f the w inter a c t i v i t i e s o f the mink.
Jour. Mamm., 1 7(U )$382-392.
McCabe, Robert A ., 19U9•’ N otes on liv e -tr a p p in g mink.
Jour. Mamm., 30(U);
U16-U23.
Newby, F le tc h e r E ., and Vernon D. Hawley, 195>U. Progress on a marten
liv e -tr a p p in g stu d y . Trans. 19th N. A. W ild l. C onf.; U52-U62.
P e tr id e s , George Ai, 1950. The determ ination o f sex and age r a t io s in fu r
anim als. Am. M idi. N a t., U3 $355-38 2 .
E it c e y , R. W., and R. T. Edwards, 1956. L ive-trap p in g mink in B r itis h
Columbia. Jour. Mamm., 3 7 ( l ) $ l l U - l l 6 .
U nited S ta te s Department o f the I n te r io r , F ish and W ild life S e r v ic e , 195U.
C reel cen su s and expenditure stu d y , Madison R iver, Montana, 1950-52.
S p e c ia l s c i e n t i f i c r ep o rt; F ish e r ie s No. 126, Washington, D. C ., 39 pp.
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