BIOLOGICAL DATA AND HABITAT REQUIREMENTS
WILDLIFE SPECIES: Lepus americanus | Snowshoe Hare 



TIMING OF MAJOR LIFE HISTORY EVENTS : 
Diurnal Activity:  Snowshoe hares are crepuscular to nocturnal.  They
are shy and secretive and spend most of the day in shallow depressions,
called forms, scraped out under clumps of ferns, brush thickets, and
downed piles of timber.  They occasionally use the large burrows of
mountain beavers (Aplodontia rufa) as forms.  Diurnal activity level
increases during the breeding season.  Juveniles are usually more active
and less cautious than adults [53].

Breeding Season:  Snowshoe hares are active year-round.  The breeding
season for hares is stimulated by new vegetation and varies with
latitude, location, and yearly events (such as weather conditions and
phase of showshoe hare population cycle) [9,35].  Breeding generally
begins in late December to January and lasts until July or August
[35,53].  In northwestern Oregon male peak breeding activity (as
determined by testes weight) occurs in May and is at the minimum in
November.  In Ontario the peak is in May and in Newfoundland the peak is
in June.  Female estrus begins in March in Newfoundland, Alberta, and
Maine, and in early April in Michigan and Colorado.  First litters of
the year are born from mid-April to May [9].

Gestation and Litter Size:  The gestation period is 35 to 40 days; most
studies report 37days as the average length of gestation.  Litters
average three to five leverets depending on latitude, elevation, and
phase of population cycle, ranging from one to seven [9,53].  Deep
snowpack increases the amount of upper-branch browse available to
snowshoe hares in winter and therefore has a positive relationship with
the nutritional status of breeding adults.  Litters are usually smaller
in the southern sections of snowshoe hare range since there is less
snow.  Newborn snowshoe hares are fully furred, open-eyed, and mobile.
They leave the natal form within a short time after birth, often within
24 hours.  After leaving the birthplace siblings stay near each other
during the day, gathering once each evening to nurse [9,53].  Weaning
occurs at 25 to 28 days except for the last litter of the season which
may nurse for 2 months or longer [64].

Pregnancy Rate and Productivity:  Female snowshoe hares can become
pregnant anytime after the 35th day of gestation.  The second litter can
therefore be conceived before the first litter is born (snowshoe hares
have twin uteri) [9].  Pregnancy rates ranged from 78 to 100 percent for
females during the period of first litter production, 82 to 100 percent
for second litters, and for the periods of third and fourth litters
pregnancy rates vary with population cycle [17].  In Newfoundland the
average number of litters per female per year ranged from 2.9 to 3.5,
and in Alberta the range was from 2.7 to 3.3 [9].  The number of litters
per year varies with phase of population cycle (see below).  In Alberta
the average number of litters per year was almost 3 just after a
population peak and 4 just after the population low [17].  Females
normally first breed as 1-year-olds.  Juvenile breeding is rare and has
only been observed in females from the first litter of the year and only
in years immediately following a low point in the population cycle [9].

Mortality:  In Yukon Territory 30-day survival of radio-tagged leverets
was 46 percent, 15 percent, and 43 percent for the first, second, and
third litter of the year, respectively.  There were no differences in
mortality in plots with food added.  The main proximate cause of
mortality was predation by small mammals including red squirrels
(Tamiasciurus hudsonicus) and arctic ground squirrels (Spermophilus
parryii).  Littermates tended to live or die together more often than by
chance.  Individual survival was negatively related to litter size and
positively related to body size at birth.  Litter size is negatively
correlated with body size at birth [57].

Population Cycles:  Northern populations of snowshoe hares undergo
cycles that range from 7 to 17 years between population peaks.  The
average time between peaks is approximately 10 years.  The period of
abundance usually lasts for 2 to 5 years followed by a population
decline to lower numbers or local scarcity.  Areas of great abundance
tend to be scattered [36,53].  Populations do not peak simultaneously in
all areas, although there is a great deal of synchronicity in northern
latitudes [3].  From 1931 to 1948 the cycle was synchronized within 1 or
2 years over most of Canada and Alaska, despite differences in predators
and food supplies [68].  In central Alberta low snowshoe hare density
occurred in 1965 with 42 to 74 snowshoe hares per 100 acres (40 ha).
The population peak occurred in November 1970 with 2,830 to 5,660
snowshoe hares per 100 acres (40 ha) [44].  In the southern parts of its
range snowshoe hare populations do not fluctuate radically [46].

Exclosure experiments in Alberta indicated that browsing by snowshoe
hares during population peaks has the greatest impact on palatable
species, thus further reducing the amount of available foods.  In this
study there was insufficient nutritious young browse available to
sustain the number of snowshoe hares present in the peak years (1971 and
1972) in winter [61].


PREFERRED HABITAT : 
A habitat suitability index model for snowshoe hare was summarized by
Carreker [16].  Major variables in habitat quality include average
visual obstruction and browse biomass.  Snowshoe hares prefer young
forests with abundant understories.  The presence of cover is the
primary determinant of habitat quality for snowshoe hares and is more
significant than food availability [16] or species composition [19,51].
Species composition does, however, influence population density; dense
softwood understories support greater snowshoe hare density than
hardwoods because of cover quality.  In Maine it was observed that
female snowshoe hares were more common on sites with less cover but more
nutritious forage; males tended to be found on sites with heavier cover
[50].

Winter browse availability depends on height of understory brush and
winter snow depth; 6- to 8-foot tall (1.8-2.4 m) saplings with narrow
stem diameters are required for winter browse in heavy snow [81].

In northern regions snowshoe hares occupy conifer and mixed forests in
all stages of succession, but early successional forests foster peak
abundance.  Deciduous forests are usually occupied only in early stages
of succession [36].  In New England snowshoe hares preferred
second-growth deciduous, coniferous, and mixed woods with dense brushy
understories; snowshoe hares appear to prefer shrubby old-field areas,
early- to mid-successional burns, shrub-swamps, bogs, and upper montane
krumholz vegetation [21].  In Maine snowshoe hares were more active in
clearcut areas than in partially cut or uncut areas.  Sapling densities
were highest on 12- to 15-year-old plots; these plots were used more
than younger stands [55].  In northern Utah snowshoe hares occupied all
the later stages of succession on quaking aspen and spruce-fir but were
not observed in meadows [66].  In Alberta snowshoe hares use upland
shrub-sapling stages of regenerating aspens (either postfire or
postharvest) [82].  In British Columbia overstocked juvenile lodgepole
pine (Pinus contorta) stands formed optimal snowshoe hare habitat [72].

In western Washington most unburned, burned, or scarified clearcuts will
normally be fully occupied by snowshoe hares within 4 to 5 years as
vegetation becomes dense [15].  In older stands (more than 25 years)
stem density begins to decline and cover for snowshoe hares decreases
[46].  However, in north-central Washington snowshoe hares may not
colonize clearcuts until 6 or 7 years and it may take 20 to 25 years for
snowshoe hare density to reach maximum [6].  Winter snowshoe hare pellet
counts were highest in 20-year-old lodgepole pine stands, lower in older
lodgepole stands, and lowest in spruce-dominated stands [46].  In
western Oregon snowshoe hares were abundant only in early successional
stages including stable brushfields [2].  In west-central Oregon an
old-growth Douglas-fir forest was clearcut and monitored through 10
years of succession.  A few snowshoe hares were noted in adjacent virgin
forest plots; they represented widely scattered, sparse populations.
One snowshoe hare was observed on the disturbed plot 2.5 years after it
had been clearcut and burned; at this stage ground cover was similar to
that of the uncut forest.  By 9 years after disturbance snowshoe hare
density had increased markedly [33].

Slope and Aspect:  In western Washington snowshoe hares routinely used
steep slopes where cover was adequate; most studies, however, suggest
that snowshoe hares tend to prefer gentle slopes [15].

Moonlight increases snowshoe hare vulnerability to predation,
particularly in winter.  Gilbert and Boutin [34] presented some evidence
that snowshoe hares tend to avoid open areas during bright phases of the
moon and during bright periods of a single night.  Snowshoe hare
activity usually shifts from coniferous understories in winter to
hardwood understories in summer [56].

Home Range:  Vegetative structure plays an important role in the size of
snowshoe hare home ranges.  Snowshoe hares wander up to 5 miles (8 km)
when food is scarce [3].  In Montana home ranges are smaller in brushy
woods than in open woods [1].  In Colorado and Utah the average home
range of both sexes was 20 acres (8.1 ha) [25].  On Montreal Island of
Quebec, the average daily range for both sexes was 4 acres (1.6 ha) in
old-field mixed woods [8].  In Montana the home range averaged 25 acres
(10 ha) for males and 19 acres (7.6 ha) for females [1].  In Oregon the
average snowshoe hare home range was 14.6 acres (5.9 ha) [58].


COVER REQUIREMENTS : 
Snowshoe hares require dense, brushy, usually coniferous cover; thermal
and escape cover are especially important for young snowshoe hares
[20,35].  Low brush provides hiding, escape, and thermal cover.  Heavy
cover 10 feet (3 m) above ground provides protection from avian
predators, and heavy cover 3.3 feet (1 m) tall provides cover from
terrestrial predators [16].  Overwinter survival of snowshoe hares
increases with increased cover [51].  A wide variety of habitat types
are used if cover is available.  Base visibility in good snowshoe hare
habitat ranges from 2 percent at 16.5 feet (5 m) distance to 0 percent
at 66 feet (20 m).  Travel cover is slightly more open, ranging from
14.7 percent visibility at 16.5 feet (5 m) to 2.6 percent at 66 feet (20
m) [16].  Wolfe and others [81] reported that areas with horizontal
vegetation density of 40 to 100 percent at 50 feet (15 m) are adequate
snowshoe hare habitat in Utah [80].


FOOD HABITS : 
Snowshoe hares eat a variety of plant materials.  Forage type varies
with season.  Succulent green vegetation is consumed when available from
spring to fall; after the first frost buds, twigs, evergreen needles,
and bark form the bulk of snowshoe hare diets until spring greenup
[9,53].

Winter Foods:  Snowshoe hares prefer branches, twigs, and small stems up
to 0.25 inch (6.3 mm) diameter; larger stems are sometimes used in
winter [35].  In Yukon Territory snowshoe hares normally eat
fast-growing birches and willows and avoid spruce.  At high snowshoe
hare densities, however, the apical shoots of small spruce are eaten
[68].  The snowshoe hare winter diet is dominated by bog birch (Betula
glandulosa) which is preferred but not always available.  Greyleaf
willow (Salix glauca) is eaten most often when bog birch is not
available.  Buffaloberry (Shepherdia canadensis) is the fourth most
common diet item.  White spruce (Picea glauca) is eaten but not
preferred.  In Alaska spruce, willows, and alders comprise 75 percent of
snowshoe hare diets; spruce needles make up nearly 40 percent of the
diet [79].  In northwestern Oregon winter foods include needles and
tender bark of Sitka spruce, Douglas-fir, and western hemlock (Tsuga
heterophylla); leaves and green twigs of salal; buds, twigs, and bark of
willows; and green herbs [53].  In north-central Washington willows and
birches are not plentiful; snowshoe hares browse the tips of lodgepole
pine seedlings [47].  In Utah winter foods include Douglas-fir, willows,
snowberry (Symphoricarpos spp.), maples, and serviceberry (Amelanchier
spp.).  In Minnesota aspens, willows, hazelnut (Corylus spp.), ferns
(Pteridophyta spp.), birches, alders, sumacs (Rhus spp.), and
strawberries (Fragaria spp.) are winter foods.  In New York winter foods
include eastern white pine, red pine (Pinus resinosa), white spruce,
paper birch, and aspens [52].  In Ontario sugar maple (Acer saccharum),
striped maple (A. pensylvanicum), red maple, other deciduous species,
northern white-cedar (T.  occidentalis), balsam fir, beaked hazelnut (C.
cornuta), and buffaloberry were heavily barked [22].  In New Brunswick
snowshoe hares consumed northern white-cedar, spruces, American beech
(Fagus grandifolia), balsam fir, mountain maple (A.  spicatum), and many
other species of browse [74].  In Newfoundland paper birch is preferred
[24].  Further details on regional food preferences are summarized in
Bittner and Rongstad [9].

Spring, Summer, and Fall Foods:  In Alaska snowshoe hares consume new
leaves of blueberries (Vaccinium spp.), new shoots of field horsetails
(Equisetum arvense), and fireweed (Epilobium angustifolium) in spring.
Grasses are not a major item due to low availability associated with
sites that have adequate cover.  In summer leaves of willows, black
spruce, birches, and bog Labrador tea (Ledum groenlandicum) are also
consumed.  Black spruce is the most heavily used and the most common
species in the area.  Pen trials suggest that black spruce is not
actually preferred.  Roses (Rosa spp.) were preferred but a minor
dietary item as they were not common in the study area [79].  In
northwest Oregon summer foods include grasses, clovers (Trifolium spp.),
other forbs, and some woody plants including Sitka spruce, Douglas-fir,
and young leaves and twigs of salal [53].  In Minnesota aspens, willows,
grasses, birches, alders, sumacs, and strawberries are consumed when
green [52].  In Ontario summer diets consist of clovers, grasses, and
forbs [22].


PREDATORS : 
The snowshoe hare is a major prey item for a number of predators.  Major
predators include lynx (Lynx lynx), bobcats (L. rufus), fishers (Martes
pennanti), American martens (M. americana), long-tailed weasels (Mustela
frenata), minks (M. vison), foxes (Vulpes and Urocyon spp.), coyote
(Canis latrans), domestic dogs (C. familiaris), mountain lions (Felis
concolor), domestic cats (F. catus), great horned owls (Bubo
virginianus), barred owls (Strix varia), spotted owls (S.
occidentalis), other owls, red-tailed hawks (Buteo jamaicensis),
northern goshawks (Accipiter gentilis), other hawks (Buteonidae), golden
eagles (Aquila chryseatos), and crows and ravens (Corvidae)
[9,16,35,53,59,75].  Other predators include northern short-tailed
shrews (Blarina brevicaula) and black bears (Ursus americanus) [9,75].
In Glacier National Park snowshoe hares are a prey item of Rocky
Mountain wolves (Canis lupus irremotus) [40].


MANAGEMENT CONSIDERATIONS : 
The snowshoe hare is an economically important species; its economic
impact varies with season, region, and population cycle [9].  It is
important prey for many furbearers (coyote, foxes, fishers, etc.), but
does not itself produce economically important fur.  Its importance as
prey creates secondary effects during population lows; predators seeking
other food sources often increase predation rates on preferred game
species such as ruffed grouse (Bonasa umbellus) [42].  The snowshoe hare
is a small game animal and is important as human food in some remote
areas [3].  It is a pest in tree plantations [53] and causes damage to
both managed and unmanaged conifer stands in the Pacific Northwest [35].

Importance as Prey:  Management of furbearers and sensitive predator
species is often dependent on snowshoe hare management as they are a
major prey item for many carnivores.  Lynx, considered a sensitive
species in Washington, can be maintained only with management for their
main prey, the snowshoe hare.  In north-central Washington a patchwork
of early successional stands favored by snowshoe hares and old-growth
forest needed by lynx for denning is recommended [83].  Logging and
thinning units of less than 40 acres (16 ha) encourage natural forest
regeneration; it is recommended that management units be greater than 20
to 25 acres (8-10 ha) (i.e., larger than the average snowshoe hare home
range) to encourage snowshoe hare use and thus benefit lynx [47].  In
Alberta winter coyote density is directly related to snowshoe hare
abundance.  Coyotes switch to alternate prey species only when snowshoe
hares become relatively scarce [76].

Black and others [10] surveyed animal damage to conifer plantations in
Oregon and Washington based on data obtained from 1963 to 1975.
Snowshoe hare damage was substantial to Douglas-fir plantations; in many
cases tree damage was second only to that caused by mule deer
(Odocoileus hemionus).  It must be noted that snowshoe hare populations
peaked in 1971 and 1972.  During population lows most damage to conifer
plantations consists of clipping of small-diameter stems, twigs, and
branches.  Barking becomes serious at high snowshoe hare densities [35].

Snowshoe hare damage birch seedlings by clipping twigs, terminal shoots,
and stems, or by gnawing bark and partially or completely girdling trees
[41].

Control:  All direct control methods are effective only in the short
term.  Lethal control methods are subject to state and local
regulations.  Shooting snowshoe hares is costly of time and personnel,
and is not always effective.  Trapping is costly.  Toxic baits are not
always legal.  Nonlethal methods include repellents, which can be
effective but costly, and exclusion fencing, which is also costly
[27,35].

Indirect control of snowshoe hares consists of habitat management to
reduce cover.  Silvicultural practices can be modified to reduce
snowshoe hare use of an area; brushy areas attract snowshoe hares.
Second-growth stands with dense brushy understories and high sapling
densities are optimum snowshoe hare habitat.  Thinning often creates
good snowshoe hare habitat when it encourages denser growth of shrubs
[35].  Snowshoe hares also favor clearcut blocks adjacent to pole-size
timber; edges are the areas of greatest snowshoe hare activity [35].

In British Columbia population density and recruitment of snowshoe hares
increased significantly in thinned stands of lodgepole pine during the
first winter but declined thereafter.  Thinning overstocked lodgepole
pine had little or no effect on reproduction or survival of snowshoe
hares but reduced average body weights [72].  In aspen-birch stands
reduction of coniferous cover in cutover areas reduces use by snowshoe
hares [41].  Evans [27] suggested that snowshoe hare damage is probably
reduced where slash and brush are disposed of by burning.  In quaking
aspen (Populus tremuloides) stands in Alberta, intensive regeneration
and periodic removal of competing brush promotes fast early growth and
reduces snowshoe hare damage [26].  Other recommendations include timing
conifer plantation establishment during the low phase of the snowshoe
hare population cycle, using larger planting stock with a reduced
fertilizer regime, and selection of tree species based on snowshoe hare
preferences [35,71,72].

The possibility of raising Douglas-fir stock that is less palatable to
snowshoe hares has been discussed [23].

Parasites and diseases of snowshoe hares have been studied extensively
and were summarized by Bittner and Rongstad [9].


REFERENCES : 
NO-ENTRY

Related categories for Wildlife Species: Lepus americanus | Snowshoe Hare