Winter hunting habitat of pumas Puma concolor in northwestern Utah and southern Idaho, USA

Abstract

The diet of pumas Puma concolor in North America con-sists primarily of large ungulates (Anderson 1983) that they stalk to kill (Koford 1946, Hornocker 1970, Sei-densticker, Hornocker, Wiles & Messick 1973, Wilson 1984). Researchers have observed that large stalking felids usually need to approach to within 15-20 m of their prey for a successful attack (Elliot, Cowan & Holling 1977, Van Orsdol 1984). To approach potential prey, stalking predators require sufficient 'hunting cover' (El-liott et al. 1977 , Van Orsdol 1984, Sunquist & Sunquist 1989). Pumas therefore should have rather specific habitat requirements for successful hunting (Hornocker 1970, Laing 1988, Sunquist & Sunquist 1989), and some field evidence supports this prediction. Logan & Irwin (1985) found higher use by pumas and more cache sites in mixed conifer and mountain mahogany Cercocarpus ledi-folius habitat in steep or rugged terrain. They 'inferred' Winter hunting habitat of pumas Puma concolor in northwestern Utah and southern Idaho, USA

Full text

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© WILDLIFE BIOLOGY · 9:2 (2003)
The diet of pumas Puma concolor in North America con-
sists primarily of large ungulates (Anderson 1983) that
they stalk to kill (Koford 1946, Hornocker 1970, Sei-
densticker, Hornocker, Wiles & Messick 1973,Wilson
1984). Researchers have observed that large stalking
felids usually need to approach to within 15-20 m of their
prey for a successful attack (Elliot, Cowan & Holling
1977, Van Orsdol 1984). To approach potential prey,
stalking predators require sufficient 'hunting cover' (El-
liott et al. 1977 , Van Orsdol 1984, Sunquist & Sunquist
1989).
Pumas therefore should have rather specific habitat
requirements for successful hunting (Hornocker 1970,
Laing 1988, Sunquist & Sunquist 1989), and some field
evidence supports this prediction. Logan & Irwin (1985)
found higher use by pumas and more cache sites in mixed
conifer and mountain mahogany Cercocarpus ledi-
folius habitat in steep or rugged terrain. They 'inferred'
Winter hunting habitat of pumas Puma concolor in northwestern
Utah and southern Idaho, USA
John W. Laundré & Lucina Hernández
Laundré, J.W. & Hernández, L. 2003: Winter hunting habitat of pumas Puma
concolor in northwestern Utah and southern Idaho, USA. - Wildl. Biol. 9: 123-
129.
Pumas Puma concolor are stalking predators of large ungulates that usually cache
their prey. We hypothesize that they require specific habitats to successfully stalk
their prey and that they select cache sites based on some set of criteria. We test-
ed these predictions during a study of predation by pumas on mule deer Odo-
coileus hemionus in south-central Idaho and northwestern Utah, USA. We found
cache points of puma-killed deer in winter by locating radio-collared pumas.
We then located where pumas had killed deer (kill points) by tracks in the snow.
We classified these kill points relative to the dominant forest type and associ-
ation with open, edge or forested areas. At a subset of the kill points and asso-
ciated cache points, we also estimated tree and shrub density, tree diameter at
breast height (dbh), shrub height and slope. Pumas killed deer more often than
expected (P < 0.001) in juniper-pinyon habitat and in edge areas. Tree densi-
ties and dbh at cache points were significantly greater (P < 0.001) than at kill
points or surrounding areas. We concluded that pumas relied on specific habi-
tat characteristics to kill mule deer, and selected cache sites with older, larger
trees.
Key words: hunting habitat, Idaho, kill-sites, mule deer, pumas, Utah
John W. Laundré, Instituto de Ecología, A.C. Durango Regional Center, Km
5 carr. a Mazatlán, 34000, Durango, Durango, México, and Idaho State Uni-
versity, Pocatello, ID 83209, USA - e-mail: launjohn@prodigy.net.mx
Lucina Hernández, Instituto de Ecologia, A.C., Durango Regional Center, Km
5 Carr. a Mazatlán, 34000, Durango, Durango, México - e-mail: lucina@
fauna.edu.mx
Corresponding author: John W. Laundré
Received 18 April 2002, accepted 9 September 2002
Associate Editor: Henryk Okarma

124 © WILDLIFE BIOLOGY · 9:2 (2003)
that animals were using these areas to approach their prey.
Laing (1988) found kill/cache sites more often than
expected in pinyon-juniper/lava rock habitat and attrib-
uted that to cover and topographic features which pro-
vided good stalking cover. Koehler & Hornocker (1991)
also found that pumas preferred specific forest types and
terrain, again ascribing this to stalking cover. Jalkotzy,
Ross & Wierzchowski (2000), in a regional scale anal-
ysis, found more kills in areas with greater terrain rug-
gedness. However, apart from these general conside-
rations and larger scale analyses, few studies have
measured specific habitat characteristics of actual sites
where pumas have captured their prey. Most of the data
are actually from cache sites which can be up to 200 m
from kill sites (J.W. Laundré, unpubl. data) and may not
represent actual kill habitat. Thus, the prediction that
pumas require specific habitat characteristics to success-
fully hunt remains untested.
Pumas hunt singly and typically kill prey larger than
themselves. Consequently they often have to cache it for
later use. Caching behaviour is common among the
large solitary felids (Schaller & Vasconselos 1978, Sun-
quist 1981) and is a method to conserve food and to pro-
tect it from scavengers and competitors, including con-
specifics (Sunquist & Sunquist 1989). Pumas cache
their prey by placing it under a tree or bush and cover-
ing it with soil, leaves, sticks (Shaw 1989) and snow.
Apart from this observation, there has been little quan-
tification of cache site characteristics for pumas. They
can drag their prey up to 200 m from the kill site, often
passing up seemingly adequate cache sites (J.W. Laundré,
pers. obs.). This would indicate that some site selection
is occurring. Thus, we predict that pumas are not caching
their prey under the first available tree, but are instead
selecting some factor or factors that make one site bet-
ter than another.
Our objective was to test the predictions that habitat
characteristics of sites where pumas killed mule deer
Odocoileus hemionus in winter and subsequently cached
them, are unique subsets of the various habitats available.
The results of testing these predictions could help in-
crease our understanding of what constitutes success-
ful winter hunting and caching habitat for pumas and po-
tentially, how habitat can affect the impact of pumas on
their prey.
Study area
Our study was performed in the counties of Cassia
(south-central Idaho) and Box Elder (northwestern
Utah), USA. The site spanned about 2,500 km2and con-
tained five small, isolated mountain ranges with eleva-
tions of 1,830-3,151 m a.s.l. Mountain ranges were
fragmented into open and forested habitat patches that
varied in size, complexity and isolation from nearby
patches. Climate was characterized by hot, dry summers
(20-35°C) and cold, windy winters (-25 to 4°C). Hu-
midity rarely exceeded 40%, and precipitation was spo-
radic with an annual mean of 30 cm.
Forested patches were divided into four major types:
1) Douglas fir, a forest type dominated by Douglas fir
Pseudotsuga menziensii but with occasional subalpine
fir Abies lasiocarpa, 2) quaking aspen Populus tremu-
loides, 3) juniper-pinyon, a woodland mix of juniper
Juniperus osteosperma and J. scopulorum and pinyon
pine Pinus edulis, and 4) curl-leaf mountain mahogany
Cercocarpus ledifolius. Dominant shrubs in open areas
included big sagebrush Artemisia tridentata, gray rab-
bitbrush Chrysothamnus nauseosus, bitterbrush Purshia
tridentata, and buffaloberry Shepherdia rotundifolia.
Methods
In the winters of 1985-2001, we located sites where
pumas cached mule deer carcasses (cache sites) by
either walking into the area of a radio-collared animal
or following tracks found crossing roads. At each cache
site, we marked the actual location of the carcass (cache
point) with flagging. When possible, we located the area
(kill site) and actual location (kill point) where the
pumas killed the deer by following tracks in the snow.
Thus, some sites located consisted only of cache
sites/points whereas for others we were able to identi-
fy cache and kill sites/points.
At identified kill points, we classified the surround-
ing site relative to macro structure in the categories
open, edge or forest. Our criteria for the open, edge or
forest designations were based on the distance from a
forest patch and/or density of trees. Sites were classi-
fied as open if they were more than 20 m outside the edge
of a forest. Edge sites were those from 20 m outside a
forest patch to 15 m into the forest patch (Altendorf,
Laundré, López-Gonzáles & Brown 2001, Holmes
2000). We also designated 'edge like' areas where the
distance among trees permitted seeing a minimum of
20 m. The 20-m limit was based on data reported for oth-
er stalking felids as the typical distance from its prey a
predator needs to approach undetected for a successful
attack (Sunquist & Sunquist 1989). Kill sites within a
forest patch and >15 m from an opening were consid-
ered forest sites. For kill sites located at edges and in
forests, we classified the forest type based on the pre-

125
© WILDLIFE BIOLOGY · 9:2 (2003)
dominant tree species (Juniper-pinyon, Douglas fir,
aspen and mountain mahogany) as described above. We
also classified the forest types at cache-only sites when
there were no other forest types within 200 m (maxi-
mum drag distance; J.W. Laundré, unpubl. data).
We revisited most sites the following summers and
measured tree density, tree diameter at breast height
(dbh), shrub density, shrub height and slope. Shrub
measurements were limited to shrubs 50 cm high or
more. We rationalized that in the winter when snow was
often >50 cm deep, shrubs <50 cm would likely not func-
tion as cover for a puma. We used the point quarter
method in measuring these characteristics (Brower,
Zar & von Ende 1990) at cache and kill points. We also
established a grid of 16 points, 10 m apart and centered
on the cache or kill points (Fig. 1) and took the same
measurements. We used the averages of the measure-
ments from these 16 points as estimates for cache and
kill sites and compared them to the data from the cache
and kill points.
To determine if kill points were equally distributed in
the three macro structural types (open, edge and forest)
we used a G-test design (Zar 1999). As pumas usually
drag their prey into forested areas (J.W. Laundré, pers.
obs.), we did not perform this test on cache sites. We also
used a G-test design to test for equal selection of for-
est type. This test included kill sites and cache sites where
we were able to identify the forest type. The expected
number of sites per structure and forest type were cal-
culated based on the percentage of each type in the study
area. As accurate vegetation maps were not available for
the area, we estimated the percentage of each category
by centering a transparent grid (1,000 grid cells) over
U.S. Bureau of Land Management and Forest Service
colour aerial photographs of the mountains in the study
area (Marcum & Loftsgaarden 1980). We limited the esti-
mation to the mountains because pumas rarely used the
valleys. Each photo covered an area of approximately
10 km2. We selected only those photos that covered ele-
vations ≥2,000 m a.s.l., because pumas in our study rarely
used areas at lower elevation (J.W. Laundré, unpubl.
data). In each photo, we randomly selected 50 of the grid
cell intersections and classified where they fell on the
photo relative to open, edge or forest and to Douglas fir,
juniper/pinyon, mountain mahogany or aspen forest
type. We then used the number of intersections in each
kill or cache point
Sample points within kill or
cache site
X
10 meters
N
Kill or cache site
Figure 1. Experimental design to measure tree density, tree diameter
at breast height (dbh), shrub density, shrub height, and slope at kill and
cache sites. Kill and cache points (x) were the center sample points of
the grid. Kill and cache sites were defined as a 50 ×50 m area surrounding
kill and cache points. All grids were oriented magnetic north-south for
uniformity.
Open Edge Forest
NUMBER OF SITES
0
5
10
15
20
25
30
35
40
45
50
x2 = 56.0
P < 0.001
DF J/P MM AP
NUMBER OF SITES
0
10
20
30
40
50
60
70
x2 = 30.1
P < 0.001
1/9
5/5
60/37
25/40
11/12
38/15
3/25
B)
A)
Figure 2. Observed (■) and expected (■■) number of kill points found
in the three structural classifications (open, edge and forest; A) and four
forest types (Douglas fir (DF), juniper-pinyon (J/P), mountain mahogany
(MM) and aspen (AP); B). The figures above the columns gives the num-
ber of observed and expected sites in each of the three structural
classes and each of the four forest types.

126 © WILDLIFE BIOLOGY · 9:2 (2003)
category to estimate the percentage covered by each
structure type.
For the micro structural analysis, we used a two-
way analysis of variance to test the null hypothesis
that cache or kill points did not differ in structure from
the surrounding cache and kill sites, nor between each
other. The first treatment (points/sites) was to test for
differences among kill points, cache points, kill sites and
cache sites. The second treatment was among the dif-
ferent kills that we found. We used this design to par-
tition out the inter-site variability and to better test the
main hypothesis of no differences among kill points,
cache points, kill sites and cache sites. We did these
analyses for the five characteristics measured and adjust-
ed the probabilities for multiple tests with a Bonferroni
correction factor (Neu, Byers & Peek 1974). If signif-
icant differences were found among sites, we used a mul-
tiple range test to identify those differences. All rejec-
tion levels were set at P < 0.05, and all means are pre-
sented with ± standard errors.
Results
We sampled 71 aerial photos (3,550 points) and based
on this analysis, forest composition in our study area con-
sisted of 44.0% Douglas fir, 40.9% juniper, 5.3% moun-
tain mahogany, and 9.8% aspen. Relative to structure
types, 48.2% of the study area ≥2,000 m a.s.l. was open
habitat, 28.5% edge habitat, and 23.3% forest.
We located cache sites of 94 deer killed by pumas. We
identified the kill points at 52 of these sites. Of these
points, pumas killed deer significantly more often in edge
and less often in open habitats (Fig. 2A). For 91 sites,
we were able to classify the forest type associated or most
likely associated with the kill sites. The remaining three
sites were classified as open and, thus, did not have a for-
est type associated with them. Based on our analysis,
pumas killed significantly more deer in the juniper-
pinyon forest type and significantly fewer in the Douglas
fir forest type (Fig. 2B).
We took measurements of microhabitat structure at 76
areas. Of these, 38 had both kill and accompanying cache
points. There were five with kill points only because
pumas killed but did not drag the deer and 33 cache-only
sites (we could not reliably determine the kill point). We
used only the 38 sites with data from both kill and
cache sites in our statistical comparison. For these
areas, we found no differences in shrub density, shrub
height, or slope among kill points, cache points, kill sites
and cache sites (Table 1). For tree densities and dbh,
means at cache points were significantly higher than those
at kill points, kill sites and cache sites (see Table 1).
Relative to our analysis of macro structure at kill
points, our field designation of these points as open, edge
and forest was based on our visual perception of the area
and was subject to possible bias. For the 43 kill points
where we took micro structural measurements, we orig-
inally classified 31 as edges, nine as forest and three as
open. To test for possible bias, we compared the means
of tree densities, dbh, shrub density, and shrub height
of these three groups to corresponding predetermined
edge, forest and open areas we previously measured in
our study area (Table 2; Altendorf et al. 2001). We
found no significant differences in any of the compar-
isons, which indicates that this bias was minimal.
Table 1. Means (± SE) of micro structure measurements at 38 kill points, kill sites (area immediately around the kill point), cache points
and cache sites (area immediately around cache point). The results of the main treatment effects (sites) from the two-way analysis of vari-
ance comparisons are presented. Where there is a significant difference among sites, the mean that was found different by multiple range
testing is indicated with an asterisk (*).
Kill point Kill site Cache point Cache site F P
Tree density (#/100 m2) 5.2 ± 1.4 3.2 ± 0.48 9.2 ± 1.3* 4.1 ± 0.5 7.4 <0.001
Tree dbh (cm) 12.7 ± 1.4 11.0 ± 0.9 17.7 ± 1.2* 12.9 ± 0.7 8.1 <0.001
Shrub density (#/100 m2) 24.0 ± 5.1 15.8 ± 3.4 13.6 ± 2.9 13.4 ± 2.4 2.1 0.10
Shrub height (cm) 76.4 ± 3.2 77.4 ± 2.8 83.4 ± 3.4 82.6 ± 2.4 2.1 0.10
Slope (%) 13.3 ± 1.3 15.8 ± 1.3 14.9 ± 1.4 15.1 ± 0.9 0.7 0.56
Table 2. Comparison of mean micro habitat structure measurements at kill points (KP) designated as open, edge and forest to the same mea-
surements made at predetermined sites (PS) (Altendorf et al. 2001). By definition, there were no tree measurements in open areas. Sample
sizes are given in parentheses. There were no statistical differences between any of the comparisons.
Edge Forest Open
KP PS KP PS KP PS
Tree density (#/100 m2) 2.9 ± 0.6 (31) 3.5 ± 0.9 (14) 14.0 ± 3.8 (9) 10.0 ± 2.8 (14)
Tree dbh (cm) 10.9 ± 2.1 (31) 10.9 ± 4.0 (14) 11.6 ± 2.1 (9) 15.9 ± 2.1 (14)
Shrub density (#/100 m2) 15.8 ± 4.2 (31) 14.3 ± 3.8 (14) 10.8 ± 3.1 (9) 11.8 ± 4.0 (14) 40.0 ± 16.6 (4) 22.9 ± 8.1 (14)
Shrub height (cm) 73.8 ± 3.7 (31) 73.3 ± 1.9 (14) 94.8 ± 8.4 (9) 78.9 ± 3.6 (14) 65.7 ± 4.3 (4) 60.1 ± 4.3 (14)

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Discussion
Other studies (Hornocker 1970, Logan & Irwin 1985,
Laing1988, Koehler & Hornocker 1991, Williams,
McCarthy & Picton1995, Jalkotzy et al. 2000) have also
documented that pumas use specific forest/terrain types
and, based primarily on cache site data, catch more
prey in these areas. Our data from actual kill points sup-
port the findings of these previous studies in that we also
found pumas killing more deer than expected in one for-
est type and less in another (see Fig. 2). However, in our
area at least, these differences were possibly more relat-
ed to winter habitat selection by deer. Juniper-pinyon
areas are usually at lower elevations and on south-
southwest facing slopes, which are used frequently by
deer in the winter (J.W. Laundré, pers. obs.). Less-
used Douglas fir areas are at higher elevations and are
used by deer early in the winter but are abandoned as
snow depths increase (J.W. Laundré, pers. obs.). Thus,
it may be more than just a forest type effect on catch-
ability of deer. Indeed, previous authors (Hornocker 1970,
Logan & Irwin 1985, Laing1988, Koehler & Hornocker
1991) have interpreted their results in terms of pre-
ferred forest/terrain types providing the right condi-
tions for pumas to successfully stalk their prey, i.e.
stalking habitat. Additionally, Laing (1988) found over-
story cover and horizontal visibility to differ from areas
of high and low puma use, indicating the possible
importance of structural characteristics. However, it
had yet to be tested if these results can be extrapolated
to where pumas actually kill deer. In our study area we
were able to identify kill points at 52 sites. Signs in the
snow indicated that pumas usually made contact with
the deer within 10 m of the initiation of pursuit, and that
deer rarely travelled more than 10-15 m after the puma
made contact. So we considered these points to be rep-
resentative of the entire attack sequence. Data from
the macro and micro structure analyses at these iden-
tified kill points clearly indicate that structural charac-
teristics are important factors, at least in the winter, and
that these characteristics are found in edge and edge-like
areas. Thus, it is not the forest type that a puma is in,
but where it is within that forest type that is important
to its winter hunting success.
Studies of other stalking felids demonstrate that these
are more successful if they approach their prey to with-
in 10-20 m before attacking (Sunquist & Sunquist
1989). Although we found no reported data, we assumed
that pumas need to approach to similar distances. Sun-
quist & Sunquist (1989) also stressed the importance of
stalking cover to enable a predator to approach unde-
tected to within these distances. For example, grass
heights of 0.3-0.8 m increased capture success of African
lions Panthera leo (Elliott et al. 1977, Van Orsdol
1984).
This need for stalking predators to approach undetected
explains the selective use of edge areas found in our
study. We would expect a low number of kills in the open
areas where the high visibility puts the puma at a dis-
advantage (Laing 1988). The low number of kills found
in the forest is likely a result of a combination of fac-
tors. Tree densities possibly are too high and obscure
the puma’s view (Laing 1988); the average density of
trees at forest kill points (see Table 2) equates to an
approximate tree-to-tree distance of 7 m (Brower et al.
1999). Additionally, deer generally use the forest area
for resting (Collins 1983). At these times deer are sta-
tionary and usually vigilant (J.W. Laundré, pers. obs.)
and have a greater chance of seeing an approaching puma
and escaping before its arrival. Forest edges or edge-like
areas, on the other hand, are areas where deer are most
likely to be moving, e.g. from feeding in open areas to
forest bed sites. Additionally, mean tree-to-tree dis-
tances are approximately 17 m which may provide ade-
quate visibility to detect moving deer but still sufficient
cover to approach undetected to within attacking dis-
tance. We propose that it is these elements of edge and
edge-like areas that enhance a puma’s ability to detect
and approach close enough to attack deer, making these
areas successful winter hunting habitat for pumas in our
area. It was difficult to ascertain actual kill points in the
summer. Thus, we do not have comparable data for this
season to test if puma hunting patterns change in this
season. Others (Seidensticker et al. 1973, Williams et al.
1995) have reported that pumas rely more on small
mammals in summer than in winter and thus, their hunt-
ing strategies may differ at these times.
For large, solitary predators like pumas, attacking a
prey larger than themselves represents a major energy
expenditure (Ackerman, Lindzey & Hemker 1986) and,
if successful, a major energy gain for that investment.
In the framework of optimal foraging theory, meat
stolen by other animals can represent a major loss of the
benefits (energy gain) relative to the costs (energy ex-
pended) and becomes a relevant aspect of the acquisi-
tion of prey. In energetic terms, then, an important con-
sideration for a predator beyond what to kill and where
to kill it is how to save that energy for its use. As the loss
of meat to other animals, including conspecifics, can be
extensive (Wright 1960, Packer 1986, Sunquist & Sun-
quist1989, Murphy, Felzien, Hornocker & Ruth 1998),
caching should be a highly developed adaptation. Most
accounts of caching behaviour in felids are quite gen-
eral, e.g. placing their kills in dense cover (Schaller &

128 © WILDLIFE BIOLOGY · 9:2 (2003)
Vasconselos 1978, Sunquist 1981, Sunquist & Sun-
quist 1989), or in the case of leopards Panthera pardus,
placing their kills in trees (Houston 1979). For pumas,
the general observation of caching their prey under
trees (Shaw 1989) was supported by our data. Because
the cache point is at the base of one or more trees, the
average distance measurement of the four quadrants at
this point would be extremely small, resulting in our
higher tree density estimates relative to the surround-
ing area (cache site). However, what we did not predict
was the significantly larger dbh estimates at the cache
points. Pumas did not randomly place their kills under
the most convenient tree but selected trees with signif-
icantly larger dbh (= older, taller trees). This suggests
that cache site selection, at least for pumas, may be both
important and complex. Why tree size would be a selec-
tion factor can only be speculated at this time. Based on
observation of tracks around kill sites, we believe that
pumas often rest up to 100 m from the cache site (J.W.
Laundré, unpubl. data). Reports by others of dead coy-
otes Canis latrans at kill sites (Boyd & O’Gara 1985,
Koehler & Hornocker 1991, Murphy et al. 1998) indi-
cate that pumas actively defend their cached prey at
times. Perhaps the taller tree at the cache site enables
pumas to maintain visual contact with the cache site and
thus, to better defend it from scavengers. Obviously,
further, more detailed analyses of cache site character-
istics than made here are needed to define the role of this
and other possible factors in the selection of cache sites
by pumas. Other factors that could be important include
height of lowest branches or basal circumference.
In conclusion, the results of our study suggest that
pumas hunt more successfully in the winter at the edges
of forest patches and select cache sites at the base of larg-
er, older trees. Thus, the effectiveness of puma preda-
tion in the winter is limited by habitat structure (Logan
& Irwin 1985) and both pumas and mule deer in our
study area are aware of these limits (Holmes 2000,Al-
tendorf et al. 2001). Additionally, Koloski & Lindzey
(2000), in a comparison between two forested areas with
different edge densities, found that within home ranges
of pumas from both areas, edge densities were equal.
Therefore, pumas may not only be selecting successful
hunting habitat, forest edges, on a localized daily scale
but also on a larger home range scale; i.e. a minimal
amount of edge in the home range may be needed to
catch sufficient prey. Based on these observations, we
predict that the use of an area by pumas in the winter,
and puma impact on prey populations during that sea-
son will be related to the proportion of successful hunt-
ing habitat available.
Successful caching of prey by pumas can reduce their
kill frequency and, thus, reduce their potential impact on
prey populations. Inadequate caching habitat might lead
to higher losses of kills, and hence a higher kill frequency
(Hornocker 1970, Murphy et al. 1998). Based on this,
we predict that prey populations in areas with good hunt-
ing but poor caching habitat would experience higher lev-
els of predation.
The implications of these predictions are that the
effects of puma predation might be managed by manipu-
lating characteristics of successful hunting and caching
habitat. Such management of predation effects via habi-
tat manipulation could potentially help reduce some cur-
rent human conflicts related to predator-prey relation-
ships.
Acknowledgements - we thank the following organizations:
ALSAM Foundation, Boone and Crockett Club, Earthwatch,
Inc., Idaho State University, National Rifle Association, The
Eppley Foundation, U.S. Bureau of Land Management, the
Northern Rockies Conservation Cooperative, Idaho Department
of Fish and Game, Mazamas, the Merril G. and Emita E. Hast-
ing Foundation, Patagonia, Inc., SEACON of the Chicago Zoo-
logical Society, the William H. and Mattie Wattis Harris
Foundation, and Utah Division of Wildlife for financial and
logistic support. We would like to thank the many Earthwatch
volunteers without whose help this work would not have
been accomplished. We also would like to thank J. Loxterman,
B. Holmes, K. Altendorf, C. López González and S. Blum for
their help in the field. We thank Harley Shaw and Ian Ross
for their helpful comments on this manuscript. Lastly, we espe-
cially thank Kevin Allred and Ken Jafek. It is only through their
tireless enthusiasm and willing use of their tracking dogs
that this study was possible.
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