Influence of Precommercial 

Thinning on Snowshoe Hares

Evelyn L. Bull, Thad W. Heater, Abe A. Clark, Jay F. Shepherd, and 

Arlene K. Blumton

United States 

Department of 

Agriculture

Forest Service

Pacific Northwest 

Research Station

Research Paper

PNW-RP-562 

January 2005
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Authors

Evelyn L. Bull is a research wildlife biologist, Thad W. Heater was a wildlife 

biologist, and Abe A. Clark was a biological technician, U.S. Department of 

Agriculture, Forest Service, Pacific Northwest Research Station, Forestry and 

Range Sciences Laboratory, La Grande, OR 97850. Heater currently can be reached 

at P.O. Box 84445, Fairbanks, AK 99708. Clark is currently a graduate student 

at Oregon State University, Corvallis, OR 97331. Jay F. Shepherd is a research 

assistant, Department of Fish and Wildlife Resources, University of Idaho, Moscow, 

ID 83843. Arlene K. Blumton is a wildlife biologist, Wallowa-Whitman National 

Forest, La Grande Ranger District, La Grande, OR 97850.
Abstract

Bull, Evelyn L.; Heater, Thad W.; Clark, Abe A.; Shepherd, Jay F.; Blumton, 

Arlene K. 2005. Influence of precommercial thinning on snowshoe hares. Res. 

Pap. PNW-RP-562. Portland, OR: U.S. Department of Agriculture, Forest Service, 

Pacific Northwest Research Station. 16 p.

Relative abundance, survival, home range, and habitat use of snowshoe hares 

(Lepus americanus) were evaluated in five precommercial thinning treatments in 

lodgepole pine (Pinus contorta Dougl. ex Loud.) stands in northeastern Oregon 

between June 2000 and July 2003. A combination of track surveys, trapping grids, 

and radiocollared hares was used to evaluate these characteristics. Relative abundance of snowshoe hare tracks was highest in unthinned control stands and lowest 

in the recently thinned stands. The highest abundance of snowshoe hares in trapping grids occurred in patch cuts (10-m-wide cuts interspersed with unthinned 

patches 10 to 30 m wide). Hare home ranges were smallest in the patch cuts. Habitat 

use changed seasonally, with hares using denser stands during summer and more 

open stands in winter. In the short term, the patch cut appeared to provide the best 

hare habitat of the treatments investigated. 

Keywords: Fuel reduction, Lepus americanus, northeastern Oregon, snowshoe hare, 

thinning.
Summary

The snowshoe hare (Lepus americanus) occurs in stands that are frequently 

thinned, but the effects of thinning on populations of this species are unknown.

We evaluated the suitability for snowshoe hares of lodgepole pine stands that had 

been (1) unthinned, (2) thinned to a 4-m spacing within 10 years, (3) thinned to 

a 3-m spacing 20 to 25 years ago, (4) thinned in a patch cut within 2 years, and 

(5) thinned in a corridor cut within 2 years. The unthinned control stands contained 

the most snowshoe hare tracks and the recently thinned stands contained the fewest. 

Patch cuts produced the most hares in trapping grids, and hares in this treatment 

had the smallest home ranges. Hares used denser stands during summer and more 

open stands in winter. Coarse woody debris provided structure that formed 

subnivean spaces used by hares in winter for hiding and thermal cover. This 

study demonstrated that unthinned stands and new thinning regimes with a high 

proportion of unthinned areas maintained or increased numbers of snowshoe hares 

for the short term.
1

Influence of Precommercial Thinning on Snowshoe Hares

Introduction

Little is known of the extent to which wildlife species may be affected by thinning 

or of thinning treatments that may minimize the effects on wildlife. The snowshoe 

hare (Lepus americanus) occurs in overstocked stands of lodgepole pine (Pinus 

contorta Dougl. ex Loud.) and is important prey for many predators, including the 

Canada lynx (Lynx canadensis) (Aubry et al. 2000, Koehler and Brittell 1990). As 

such, habitat management activities that influence snowshoe hares likely will influence populations of the predators as well. The historical presence of lynx in northeastern Oregon (McKelvey et al. 2000) and their recent listing as threatened under 

the Endangered Species Act have added the responsibility of managing lynx to land 

management agencies (Ruggerio et al. 2000).

The preference of snowshoe hares for habitat with dense vegetative cover 

and their avoidance of open habitats has been well documented (Adams 1959, Cox 

et al. 1997, Hodges 2000a, Orr and Dodds 1982, Sullivan and Moses 1986). In 

Washington, Koehler (1990) found the highest snowshoe hare use in 20-year-old 

stands of lodgepole pine (15,840 stems per ha) compared to stands of lodgepole pine 

older than 43 years, mature stands of spruce (Picea engelmannii Parry ex Engelm.) 

and subalpine fir (Abies lasiocarpa (Hook.) Nutt.), mature stands of mixed conifer, 

and meadows. In British Columbia, overstocked stands of young lodgepole pine 

covering areas that had burned were optimal habitat for snowshoe hares (Sullivan 

and Sullivan 1988); snowshoe hare abundance had declined 2 years after lodgepole 

pine stands were thinned from about 40,000 stems per ha to 2,304 stems per ha at a 

2-m-by-2-m spacing. Dense stands of lodgepole pine provided thermal and security 

cover, in addition to the greatest amount of browse for hares during winter (Koehler 

1990).

The Canada Lynx Conservation Assessment and Strategy (Ruediger et al. 

2000) states that more information is needed on precommercial thinning to determine the potential impacts to snowshoe hare and lynx habitat. Precommercial 

thinning reduces the density of saplings and understory shrubs and is likely detrimental in the short term to snowshoe hares, but information is lacking on the effect 

on hare abundance, survival, and home range size. At present, no modifications to 

traditional thinning techniques (3-m or 4-m tree spacing) have been developed with 

the objective of addressing this wildlife habitat concern. This study investigates the 

effects of precommercial thinning treatments in lodgepole pine on snowshoe hares, 

specifically corridor and patch thinning regimes. Our objectives were to compare 

relative abundance of snowshoe hares by using winter track surveys and trapping 

grids in five treatments of precommercial thinning in 25- to 40-year-old lodgepole pine stands. In addition, we compared survival and mortality, home range, 
2

RESEARCH PAPER PNW-RP-562

and habitat use of radiocollared snowshoe hares as an indication of habitat quality 

among the thinning regimes. 

Methods

Two study areas (Anthony Burn and Indian Creek) in the Wallowa-Whitman 

National Forest were selected on the basis of containing (1) snowshoe hare habitat, 

(2) potential lynx foraging habitat, and (3) stands that could be thinned within a 

year because the National Environmental Policy Act (NEPA) analysis for precommercial thinning had been completed. Anthony Burn contained stands of 40-yearold lodgepole pine that had regenerated after a stand-replacement fire in 1960. The 

2000-ha study area consisted of stands of lodgepole pine, most of which were 

thinned 25 years ago to promote tree growth. Less than 10 percent of this study 

area had been recently thinned to a 4-m spacing to promote tree growth, but there 

had been no other harvesting since the salvage operations following the fire. 

Lodgepole pine was the predominant tree species with a minority of western 

larch (Larix occidentalis Nutt.) and subalpine fir. Elevation of the Anthony Burn 

study area is 1710 to 1940 m. Snow was usually present from November through 

May at depths of 1 to 2 m. 

Indian Creek contained 3000 ha of stands that regenerated after extensive 

harvesting in the 1970s. The harvesting followed an outbreak of the mountain pine 

beetle (Dendroctonus ponderosae) that had killed the lodgepole pine in the overstory. Most of the stands in this study area were now multilayered mixed conifer 

and had approximately an equal mix of lodgepole pine, western larch, and subalpine fir. There was a greater component of larch and subalpine fir in some of these 

stands than in the Anthony Burn. More than 75 percent of this study area had been 

logged or thinned in the last 20 to 25 years for commercial value. Elevation was 

1500 to 1680 m with snow present from November through April at depths of 

0.5 to 1.5 m.

Stand structures in the two study areas included stem initiation, stem exclusion, 

young multiage, and old multiage (Oliver and Larson 1990). Approximately 80 to 

100 percent of each treatment stand consisted of the stem exclusion structure with 

trees 8 to 12 m tall with the remainder being young multilayered stands that were 

taller than 15 m. Stands of stem initiation and old multiage occurred outside the 

treatment stands. 

Treatments

This study included five treatments: (1) stands thinned to a 4.2-m spacing within 

the last 4 to 10 years (recent thinning), (2) stands thinned in 2000 in corridors 
3

Influence of Precommercial Thinning on Snowshoe Hares

(20 to 200 m wide) that alternated between unthinned trees and trees thinned to 

a 3-m spacing (corridor cut), (3) stands thinned in 2000 in 10-m circular patches 

where all the trees were removed and were surrounded by unthinned areas 10 to 

50 m wide (patch cut), (4) stands thinned 20 to 25 years ago to a 3-m spacing (old 

thinning), and (5) stands of unthinned trees (control) (fig. 1). Randomization of the 

treatments was not possible because there were only three untreated stands larger 

than 10 ha in Anthony Burn for the control, patch cut, and corridor cut. We selected 

the only available stands that were adjacent to a groomed snowmobile route for 

the old and recent thinning treatments in the Anthony Burn. In Indian Creek there 

was only one old thinning treatment available, and we selected the only available 

stands that had not been thinned in the past that were more than 10 ha in size for the 

control, patch cut, and recent thinning. The size of treatment area for the patch and 

corridor cuts was restricted because of the past thinning that had occurred; other 

untreated stands were not available within the area approved for thinning by NEPA.

Figure 1—Illustration of relative tree spacing in five thinning treatments 

in stands of lodgepole pine in northeastern Oregon.
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RESEARCH PAPER PNW-RP-562

The patch and corridor cuts were designed specifically to improve and prolong 

the suitability of hare habitat with a secondary objective of promoting tree growth 

and reducing tree spacing for fire, insect, and disease reduction in the stands. The 

pretreatment condition of the patch and corridor cuts was similar to the control 

stands. The patch and corridor cuts were implemented in October 2000, and about 

50 percent of the area in each stand was thinned. The leave trees in the portion of 

the corridors that were thinned were predominantly lodgepole pine in the Anthony 

Burn and western larch in Indian Creek. Each of the five treatments occurred in 

single stands in each study area; additional stands for replicates were not available because of past management practices. The stand sizes for Anthony Burn and 

Indian Creek were 10 and 15 ha in recent thinning, 33 and 17 ha in corridor cuts, 15 

and 16 ha in patch cuts, 35 and 54 ha in old thinning, and 12 and 40 ha in controls, 

respectively.

Track Surveys

We conducted track surveys during two winters (2001–02 and 2002–03) in Anthony Burn and Indian Creek in each of the five treatments. One 100-m transect 

was established and flagged in the central portion of each stand. Each transect was 

about half in thinned and half in unthinned portions of the patch cuts and corridor 

cuts. Track surveys were conducted at least 24 hours but not more than 5 days after 

a new snow. All individual snowshoe hare tracks that crossed the transect were 

recorded, and we estimated the number of tracks on runways as 3, 6, 9, or 12, depending on the relative degree of use (Koehler 1990). The number of tracks per 100 

m per night without snow was calculated. A successive track survey was conducted 

only after additional snow fell; four or five surveys were conducted each winter in 

each area. Track surveys were not conducted if the snow was crusted.

Live Trapping 

Relative abundance of hares was determined by live trapping in four treatments in 

the Anthony Burn and Indian Creek study areas. Hares were trapped in a 4-by-6 

grid with traps at 50-m intervals (3.8 ha). Hares were trapped in Tomahawk live 

traps (model 205, Tomahawk, Wisconsin 54487) during June and July 2000 in 

Anthony Burn only and in both study areas during August and September 2001 and 

June and July 2002. Two recently thinned stands were set with traps in Anthony 

Burn in 2000; the low hare abundance in these stands (based on trapping and track 

surveys) suggested that further trapping was not cost effective. Traps were set for 

four nights (96 trap nights for each stand), baited with alfalfa cubes and apples, 

covered with bark or boughs, and checked each morning. Trapping grids were 
5

Influence of Precommercial Thinning on Snowshoe Hares

0.7 to 4.8 km apart to reduce the probability of hares using more than one grid. 

Hares were weighed, equipped with a radiocollar (model MI-2, Holohil Systems, 

112 John Cavanagh Rd., Carp, Ontario, Canada), and ear-tagged. Hares <425 g 

were considered juveniles and were not collared because they were too small. To 

increase the sample size of radiocollared hares, additional trapping occurred in the 

Anthony Burn in June and September 2000 and October and November 2001 and 

in Indian Creek in September 2002. Trapping was not limited to grids during these 

times, so abundance was not compared. 

Survival

Survivorship estimates were calculated at 1-month intervals for radiocollared hares 

in each treatment by using the Kaplan-Meier method (Pollock et al. 1989). Survival 

was treated separately for the two study areas because the hares were monitored 

in different years. Hares frequently ventured outside the stand where they were 

captured, so each hare was assigned to the treatment where it was most frequently 

found. Each hare was located once each week to verify that it was alive. If the 

hare was dead, we searched the immediate area for evidence of cause of mortality. Collars found at a pluck site (where the skeleton was intact but the muscle had 

been removed from the bone) were attributed to a raptor. If a portion of the carcass 

remained, a necropsy was performed to determine the presence of hemorrhaging 

(as an indicator of predation) and to measure the spacing of any punctures in the 

muscle to determine the probable predator. The distance between the tips of two 

upper canines averages 10 to 12 mm in martens (Martes americana), 22 to 27 mm 

in bobcats (Lynx rufus), and 26 to 28 mm in coyotes (Canis latrans) (Bull and 

Heater 2001). Predation by coyotes and by bobcats were combined owing to difficulty in distinguishing them. Collars found on the ground with no accompanying 

evidence were attributed to an unknown predator, unless bite marks on the collar 

matched the intercanine spacing listed above. 

Home Range 

Home range sizes were calculated for each hare with more than 25 locations by 

using the 95-percent minimum convex polygon method (Odum and Kuenzler 1955). 

Although there are numerous methods of calculating home range (see review in 

Hodges 2000b of hare home range studies), the primary objective was comparing 

home ranges among treatments. Home ranges were calculated by using hare locations during daylight hours, which primarily represent the area used for rest sites. 

These home ranges may not be representative of foraging hares because of the 

primarily nocturnal behavior of the species. 
6

RESEARCH PAPER PNW-RP-562

Habitat Use

Habitat use by hares was determined from June 2000 through October 2002 in 

Anthony Burn and from June 2002 through July 2003 in Indian Creek. Our objective was to document the range of habitat conditions used by radiocollared hares in 

the various treatments and compare habitat used at rest sites in summer and winter 

to determine if structural features were used seasonally. We did not compare used 

habitat with unused or available habitat; unused habitat could not be defined as all 

the hares in the study areas were not captured and monitored. It was not feasible 

to determine the available habitat for each hare because hare home ranges overlap 

extensively (Hodges 2000b). 

Radiocollared hares were located once per week during daylight hours (between 0700 and 1700 hr). The exact spot where the hare was sitting was identified 

when possible; triangulation was not used. At each hare location, a 5-by-5 m square 

plot (0.0025 ha) was delineated, and the following habitat characteristics recorded: 

forest type (lodgepole pine, grand fir, subalpine fir), structural stage, thinning history, canopy closure (percentage), stem density, log density, number of deciduous 

stems, number of live branches within 0.5 m of the ground (or snow), and ground 

cover composition (i.e., percentage of grass, forbs, wood debris, and bare ground). 

The number of live branches was recorded to indicate browse availability and cover 

within 0.5 m of the ground or snow. During winter, snow depth and the presence 

of a subnivean site within 3 m of the hare were recorded as well. We recorded each 

hare location with a global positioning system (GPS) that was accurate to within 

15 m. 

Analysis

A one-way analysis of variance and post-hoc Tukey’s B multiple comparison test 

were used to determine differences among treatments (both study areas combined) 

for relative abundance of hare tracks, hares captured, and home range size. As this 

species may be cyclic in more southern latitudes (Hodges 2000a), we compared 

hare density among treatments for a time period and not between years. Although 

most hares in the thinned treatments also used unthinned stands, each hare was assigned to the type of stand where the majority of the locations occurred for comparisons of survival and home range size. For habitat analyses we chose the vegetation 

plot as the sample unit because individual hares used different treatments. Therefore, we could not analyze by individual hares to test for treatment effects, which 

introduces the possibility of pseudoreplication. Categorical and continuous habitat 
7

Influence of Precommercial Thinning on Snowshoe Hares

variables were compared between summer and winter with Mann-Whitney UWilcoxon Rank tests and t-tests, respectively. The percentages of ground cover 

and log density were not compared between seasons because they could only be 

recorded when snow was absent. 

Results

Relative abundance of snowshoe hare tracks in winter differed significantly among 

the five treatments during 2001-03 (F = 11.97; 4, 84 df; P <0.01; fig. 2). The Tukey’s 

B multiple comparison test indicated that track abundance was lower in the recent 

and old thinnings than in other treatments. On the transects in the corridor cut for 

both winters combined, 72 percent of the tracks were in the unthinned portions of 

the corridors.

Figure 2—Mean number of snowshoe hare tracks per 100 m of transect per night without snow 

in lodgepole pine stands for five treatments in northeastern Oregon during nine surveys between 

December 2001 and March 2003.

In all, 31 and 42 hares were captured on the trapping grids in Anthony Burn 

and Indian Creek, respectively. Snowshoe hare abundance was significantly higher 

in the patch cuts for both study areas in 2001–02 (1 year posttreatment) (F = 9.79; 4, 

13 df; P <0.01) than the other treatments (figs. 3 and 4). Hare abundance in the Anthony Burn was lower in the corridor cut after treatment than before but was higher 

in the patch cut after treatment than before (fig. 3).
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RESEARCH PAPER PNW-RP-562

Figure 4—Number of snowshoe hares captured during 96 trap nights in Indian Creek between June 

and September 2001–02 in four thinning treatments. Trapping occurred only during posttreatment.

Figure 3—Number of snowshoe hares captured during 96 trap nights in the Anthony Burn between 

June and September 2000–2002 in five thinning treatments. Pretreatment trapping occurred in 2000 

and posttreatment trapping in 2001–02. Two stands with recent thinning were trapped only in 2000.
9

Influence of Precommercial Thinning on Snowshoe Hares

Home ranges (95-percent minimum convex polygon) of the 51 hares with more 

than 25 locations averaged 10.0 ha (range = 0.4 to 49.6 ha). Average home range 

size in patch cuts was the smallest (mean = 5.6 ha, SE = 1.48) when compared with 

corridor cuts (mean = 10.1 ha, SE = 2.78), controls (mean = 12.5 ha, SE = 2.65), and 

old thinning (mean = 15.6 ha, SE = 4.42). Given the high variability, there was no 

statistical significance (F = 2.15; 3, 47 df; P = 0.11), but there is some suggestion 

that home range size differs by treatment. 

Survival may reflect quality of habitat of the treatments investigated. In the 

Anthony Burn, 64 hares (43 adults, 21 juveniles) were radiocollared in the summers of 2000 and 2001. Only four of these hares were known to be alive at the 

end of the monitoring in October 2002; 52 had died, 6 had radios that failed, and 

2 had chewed the collar off. Of those hares that died, 24 were killed by mammals 

(bobcats, coyotes, martens), 5 by raptors (accipiters and owls), 22 by unknown 

predators, and 1 had abscesses on the liver. Although sample sizes were limited for 

all treatments except the control stands, the Kaplan-Meier survivorship estimates 

were highest in the control stands after 12 months but were the same in the control 

and corridor cut after 24 months (table 1). 

Table 1—Average Kaplan-Meier survivorship estimates (variance) for snowshoe 

hares in four thinning treatments in two study areas in northeastern Oregon, 

2000–2003

Study area/time interval Corridor cut Patch cut Old thinning Control

Anthony Burn 

 6 months 0.50 (0.06) 0.58 (0.03) 0.33 (0.04) 0.64 (0.01)

 12 months .25 (0.02) .23 (0.04) .17 (0.02) .59 (0.01)

 24 months .12 (0.1) — 0 .13 (0)

Number of hares 5 11 4 41

Indian Creek 

 6 months .75 (0.05) .48 (0.02) — .33 (0.07)

 12 months .50 (0.12) .2 (0.01) — —

Number of hares 6 14 1 3

— = Not enough hares to calculate survival.

Note: Hares were monitored for 13 months in all stands in Indian Creek, for 14 months in the patch cut in 

Anthony Burn, and for 27 months in the other stands in Anthony Burn.

In Indian Creek, 25 hares (21 adults, 4 juveniles) were radiocollared in the 

summer of 2002. Four were known to be alive at the end of monitoring in July 

2003, 18 had died, and 3 were missing. Of the hares that died, 9 were killed by 

mammals, 1 by a raptor, 6 by unknown predators, and 2 from handling. KaplanMeier survivorship estimates were higher in the corridor cut than in the patch cut 

(table 1). 
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RESEARCH PAPER PNW-RP-562

Mortality was low during winter months with snow and was high during the 

snow-free months. Of the 52 hares that died at Anthony Burn, 50 percent died from 

April through July, 46 percent from August through November, and 4 percent from 

December through March. Of the 18 hares that died at Indian Creek, 33 percent 

died from April through July, 50 percent died from August through November, and 

17 percent from December through March. 

Habitat Use

We obtained 2,565 locations of 87 hares from June 2000 through July 2003. The 

different thinning treatments resulted in obvious differences in the density of live 

stems, live branches within 0.5 m of the ground, canopy closure, and logs available 

within the stands. The patch and corridor cuts had both unthinned portions and 

small areas with no trees or trees thinned to a 3-m spacing, respectively. Stands 

with old thinning had a more open canopy, which resulted in more ground vegetation than occurred in the unthinned stands. These treatments provided various 

options of habitat conditions, which are reflected in the habitat used; significant differences were detected in all but two of the continuous variables when hare use was 

compared among treatments (table 2). About half (57 percent) of the hares in the 

corridor cut were located in the unthinned portions, whereas two-thirds of the hares 

in the patch cuts were found in the unthinned portions. Both of these treatments 

contained a high density of logs from the thinning slash.

Table 2—Mean (standard error) measurements of habitat characteristics at snowshoe hare rest sites in four 

treatments in northeastern Oregon, 2000–2003

Characteristic Corridor cut Patch cut Old thinning Control F value P value

Stem density (number/plot) 17 (1.1)ab 40 (1.4)abc 11 (0.6)a

 32 (1.0)abc 71.60 <0.01

Live branches (number/plot) 46 (2.8)b

 55 (2.8)ac 35 (2.5)a 62 (1.9)abc 15.22 <0.01

Deciduous stems (number/plot) 12 (2.5)c 19 (1.9)abc 4 (1.4)a 7 (1.0)b 16.33 <0.01

Canopy closure (percent) 73 (1.6)ab 87 (0.7)abc 68 (1.3)a 84 (0.6)ac 71.50 <0.01

Ground cover (percent).

 Bare ground 32 (2.0)ab 35 (1.3)a 19 (3.4)a 39 (1.1)ab 7.95 <0.01

 Forbs 25 (1.8)a 25 (1.1)b 52 (5.2)abc 34 (0.6)abc 19.11 <0.01

 Woody debris 29 (2.2)abc 24 (1.2)abc 12 (1.4)a 18 (0.5)b 22.18 <0.01

 Grass 4 (0.7) 6 (0.5) 11 (4.4) 6 (0.6) 2.35 0.07

 Other 10 (1.8)a 10 (1.0)a 6 (2.4) 4 (0.5)a 15.07 <0.01

Woody debris (number/plot)

 Logs 5–20 cm diameter 9 (1.1)ab 10 (0.7)ab 3 (0.3)a

 4 (0.2)b 38.68 <0.01

 Logs 21–50 cm diameter 1 (0.1) 2 (0.2) 1 (0.2) 2 (0.1) 2.06 0.10

 Logs >50 cm diameter <1 (0.3)a <1 (0)a <1 (0) <1 (0) 4.31 <0.01

Number of plots 289 558 242 1,123

Note: Habitat plots were 25 m2. Same superscripts indicate significant differences among treatments from a posthoc Tukey’s B analysis.
11

Influence of Precommercial Thinning on Snowshoe Hares

Habitat use by season was significantly different for forest type (Z = -3.70, 

P <0.01), structural stage (Z = -7.73, P <0.01), and harvest activity (Z = -3.83, 

P <0.01) with a tendency for hares to use more open stands in winter and denser 

stands in summer. Hare use of more open sites in winter is also reflected in the 

lower density of live stems, deciduous stems, and canopy closure at hare locations 

compared to use in summer (table 3). Use of lodgepole pine stands increased from 

49 percent in summer to 62 percent in winter, while use of subalpine fir stands decreased from 38 percent in summer to 28 percent in winter. Lodgepole pine stands 

were typically less dense than subalpine fir.

Table 3—Mean (standard error) measurements of habitat characteristics at 

snowshoe hare rest sites in summer and winter in northeastern Oregon, 

2000–2003

Characteristic Summer Winter t value df P value

Stem density (number/plot) 34 (1.0) 25 (0.07) 7.54 2,123 < 0.01

Live branches (number/plot) 56 (2.0) 53 (1.6) 1.26 2,309 < 0.01

Deciduous stems (number/plot) 18 (1.4) 3 (0.05) 9.75 1,475 < 0.01

Canopy closure (percent) 84 (0.06) 78 (0.6) 6.37 2,400 < 0.01

Note: Habitat plots were 25 m2. Logs and ground cover could not be measured in winter when snow was present.

df = degrees of freedom.

Use of the control stands (unthinned) decreased from 90 percent in summer to 

56 percent in winter. The use of stands with old thinning, which were more open 

than control stands, increased to 24 percent in winter compared to only 3 percent in 

summer. Only 6 percent of the locations occurred in patch and corridor cut in summer, but these increased to 15 percent in winter. 

The majority (64 percent) of summer locations were in stem exclusion stands, 

with 24 percent in young multistory stands, and 10 percent in old multistory stands. 

Use of structural stages in winter was 72 percent in stem exclusion, 23 percent 

in young multistory stands, and 5 percent in old multistory stands. Seventy-five 

percent of winter locations had a subnivean site within 10 m; 61 percent of the 

subnivean sites were formed by branches in snow and 39 percent by coarse woody 

debris. 

Discussion

Although this study had limitations of stand size and the number of replicates, our 

findings suggest that the patch cut is a promising silvicultural treatment for snowshoe hares, at least in the short term. The patch cut appears to provide foraging and 

hiding cover for hares, and we know of no other study that has evaluated this kind 
12

RESEARCH PAPER PNW-RP-562

of modification to stand structure. It is unknown if the patch cut will continue to 

provide suitable habitat in the long term; follow-up studies would be required to 

determine suitability over time. 

Of the thinning treatments, the highest numbers of trapped hares and the smallest home ranges occurred in the patch cuts, whereas traditional methods of thinning 

stands of precommercial lodgepole pine (recent thinning and old thinning) resulted 

in lowest numbers of snowshoe hares. In the short term, the patch cut appeared 

to provide the best habitat of those treatments investigated. The hare numbers 

that we found in patch cuts are characteristic of peak densities found in southern 

montane forests (1 to 2 hares/ha; Hodges 2000a), and hare densities found in the 

other treatments were lower than these (figs. 3 and 4). Home ranges reported in this 

study were similar to the 5-to-10-ha home range size reported by numerous studies 

reviewed by Hodges (2000b).

The two new thinning regimes (patch and corridor cuts) were developed 

specifically to improve habitat for hares as compared to traditional thinning treatments, and we are not aware of these treatments being used elsewhere. Because 

of the low hare abundance in the corridor cuts and the lack of hare use of the 

thinned portions of this treatment during winter, we did not find that the corridor 

treatments with the widths used in this study improved hare habitat or survival 

over untreated stands. Interpretation of the corridor cut is difficult owing to the lack 

of consistency in the width of the thinned corridors. The corridor-cut stands with 

wide strips (200 m) of thinning probably functioned as separate stands and mimicked the low hare use we observed in the recent thinning. In the 200-m wide 

corridors, hares seldom ventured into the thinned portions during winter, but hares 

regularly crossed a thinner corridor (20 m wide) in winter in Anthony Burn. The 

tree growth benefit in the corridor cut would probably exceed that of the patch cut. 

If the thinning were done when the trees were young and a low crown base were 

retained, it would likely provide better habitat for hares than what we observed 

because it would retain cover from the branches low to the ground. 

Cover provided by vegetation and coarse woody debris within 1 m of the 

ground appeared to be important for hares, particularly in summer. Slash from the 

patch and corridor cuts provided both forage and dense hiding cover for a year after 

treatment. Coarse woody debris provided hiding cover at more than half the rest 

sites in summer, and created subnivean habitat at many of the rest sites in winter. 

Subnivean sites occurred at 75 percent of the rest sites, and either coarse woody 

debris or branches at or below the snow level provided suitable subnivean habitat. 

The low vegetative cover and coarse woody debris provided hiding cover from both 
13

Influence of Precommercial Thinning on Snowshoe Hares

mammalian and avian predators. In Utah, Wolfe et al. (1982) found a strong association between hare use and the density of horizontal cover of understory vegetation at heights of 1 to 2.5 m owing to the protection it provided from terrestrial and 

avian predators. They suggested that less than 40 percent vegetation cover above 

the snow precluded use by snowshoe hares. 

The high rate and type of predation we observed are consistent with the literature (Hodges 2000a, Keith et al. 1993). Our semiannual and annual survivorship estimates (table 1) were higher than those reported in Wisconsin (semiannual 

survival 0.29 to 0.59; annual survival 0.015 to 0.179; Keith et al. 1993). In our study, 

the majority of predation was from bobcats and coyotes from spring through fall; 

little predation occurred in winter. Lynx are not present in our study area, and deep 

powder snow kept bobcats, mountain lions (Puma concolor), and coyotes out of the 

study area during most of the winter. If lynx had been present in our study area, we 

would have expected greater predation during winter owing to their ability to move 

through deep powder snow. The absence of lynx and the low predation in winter 

may explain our observations of hares moving into more open habitat in winter, 

which differs from Litvaitis et al. (1985), Parker et al. (1983), and Shaw (2002) who 

reported that denser cover was used by hares in winter. 

Our data from northeastern Oregon suggest that precommercial thinning of 

lodgepole pine in 10-m-wide patch cuts dispersed across less than 50 percent of a 

stand increased the abundance of snowshoe hares compared to the other thinning 

treatments in northeastern Oregon in the short term. This treatment provides dense 

hiding cover in proximity to small patches of more open foraging habitat. Precommercial thinning in patch cuts may be a useful tool in treating stands to improve 

snowshoe hare habitat and may provide management with options in treating stands 

within lynx habitat that could otherwise not be altered. These treatments could represent a compromise that could allow some thinning to help reduce the fuel loading and fire risk but minimize the detrimental effects to snowshoe hares and other 

wildlife dependent on overstocked, dense stands.

Acknowledgments 

Ed Baird, Cathy Nowak, and Dave Wyland assisted with field work. Karen Hodges, 

Susan Johnson, Bob Naney, John Shaw, and Barb Wales reviewed an earlier draft of 

the manuscript. Thinning treatments were implemented by the La Grande Ranger 

District. Funding was provided by the Blue Mountains Demonstration Area and 

the Pacific Northwest Research Station. Hares were handled under Oregon Permit 

Numbers 015-00, 013-01, and 057-02.
14

RESEARCH PAPER PNW-RP-562

English Equivalents

When you know: Multiply by: To find:

Millimeters (mm) 0.039 Inches

Meters (m) 3.28 Feet

Kilometers (km) 0.62 Miles

Hectares (ha) 2.47 Acres

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