BIOLOGICAL DATA AND HABITAT REQUIREMENTS
WILDLIFE SPECIES: Lepus californicus | Black-Tailed Jackrabbit 



TIMING OF MAJOR LIFE HISTORY EVENTS : 
Breeding:  Male black-tailed jackrabbit reach sexual maturity at about 7
months of age [54].  Females usually breed in the spring of their second
year, although females born in spring or early summer may breed in their
first year.  Ovulation is induced by copulation [24].  The breeding
season is variable depending upon latitude and environmental factors.
In the northern part of its range in Idaho, black-tailed jackrabbit
breeds from February through May [32].  In Utah, Gross and others [40]
reported breeding from January through July, with over 75 percent of
females pregnant by April.  The Kansas breeding season extends from
January to August [68].  Breeding in warm climates continues nearly
year-round.  Two peak breeding seasons corresponding to rainfall
patterns and vegetation greenup occur in California [54], Arizona [81],
and New Mexico [20].  In Arizona, for example, breeding peaks during
winter (January-March) rains and again during June monsoons [81].

Gestation and Nesting:  The gestation period ranges from 41 to 47 days
[40,44].  More litters are born in warm climates:  Number of litters
born each year ranged from two per year in Idaho [30] to seven in
Arizona [81].  Litter sizes are largest in the northern portions of
black-tailed jabbit's range, however, and decrease with latitude.
Average litter size has been reported at 4.9 in Idaho [30], 3.8 in Utah
[40], and 2.2 in Arizona [81].

Female black-tailed jackrabbit do not prepare an elaborate nest.  They
give birth in shallow excavations called forms that are no more than a
few centimeters deep.  Females may line forms with hair prior to
parturition, but some drop litters in existing depressions on the ground
with no further preparation [67,68].  Young are borne fully furred with
eyes open, and are mobile within minutes of birth [24,90].  Females do
not protect or even stay with the young except during nursing [65].
Ages of weaning and dispersal are unclear since the young are well
camouflaged and rarely observed in the field.  Captive black-tailed
jackrabbit are fully weaned by 8 weeks [81].  The young apparently stay
together for at least a week after leaving the form [24,65].


PREFERRED HABITAT : 
The black-tailed jackrabbit is a habitat generalist.  It can occupy a
wide range of habitats as long as there is diversity in plant species
and structure.  It requires mixed grasses, forbs, and shrubs for food,
and shrubs or small trees for cover [48,55,60,36].  It prefers
moderately open areas without dense understory growth and is seldom
found in closed-canopy habitats.  For example, Bell and Stadinski [4]
reported that in California, black-tailed jackrabbit was plentiful in
open chamise (Ademostoma fasciculatum)-Ceanothus spp. chaparral
interspersed with grasses, but did not occupy closed-canopy chaparral.
Similarly, black-tailed jackrabbit occupies clearcuts and early seral
coniferous forest, but not closed-canopy coniferous forest [8,39,80].

Black-tailed jackrabbit does not migrate or hibernate during winter
[24,39]; therefore, the same habitat is used year-round.  There is
diurnal movement of 2 to 10 miles (3-16 km) from shrub cover in day to
open foraging areas at night [24].  Home range area varies with habitat
and habitat quality [39].  Home ranges of 0.4 to 1.2 square miles (1-3
sq km) have been reported in big sagebrush (Artemisia tridentata) and
black greasewood (Sarcobatus vermiculatus) communities of northern Utah
[65].


COVER REQUIREMENTS : 
Black-tailed jackrabbit require shrubs or small conifers for hiding,
nesting, and thermal cover, and grassy areas for night feeding [24,48].
A shrub-grassland mosaic or widely spaced shrubs interspersed with herbs
provides hiding cover while providing feeding opportunities.  Small
shrubs do not provide adequate cover [18,19,48].  On the Snake River
Birds of Prey Study Area of southwestern Idaho, black-tailed jackrabbit
was more frequent on sites dominated by big sagebrush or black
greasewood than on sites dominated by the smaller shrubs winterfat
(Krascheninnikovia lanata) or shadscale (Atriplex confertifolia).
Black-tailed jackrabbit does not habitually use a burrow [60], although
it has occassionally been observed using abandoned burrows for escape
[81] and thermal [24,65] cover.


FOOD HABITS : 
The black-tailed jackrabbit diet is composed of shrubs, small trees,
grasses, and forbs.  Throughout the course of a year, black-tailed
jackrabbit feed on most if not all of the important plant species in a
community [2].  Growth stage and moisture content of plants may
influence selection more than species [46].  Shrubs generally comprise
the bulk of fall and winter diets, while grasses and forbs are used in
spring and early summer.  This pattern varies with climate:  Herbaceous
plants are grazed during greenup periods while the plants are in
prereproductive to early reproductive stages, and shrubs are utilized
more in dry seasons [2,29,59,82].  Shrubs are browsed throughout the
year, however.  Most of a jackrabbit's (Lepus spp.) body water is
replaced by foraging water-rich vegetation [81,85].  Jackrabbit require
a plant's water weight to be at least five times its dry weight in
order to meet daily water intake requirements.  Therefore, black-tailed
jackrabbit switch to phreatophyte shrubs when herbaceous vegetation
cures [38,85].

Plant species used by black-tailed jackrabbit are well documented for
desert regions.  Forage use in other regions is less well known;
however, it is well established that black-tailed jackrabbit browse
Douglas-fir (Psedotsuga menzeisii), ponderosa pine (Pinus ponderosa),
lodgepole pine (P. contorta), and western hemlock (Tsuga heterophylla)
seedlings, and oak (Quercus spp.) seedlings and sprouts [22,39,43].

Great Basin:  Big sagebrush is a primary forage species and is used
throughout the year; in southern Idaho it formed 16 to 21 percent of the
black-tailed jackrabbit summer diet.  Rabbitbrush (Chrysothamnus spp.),
spiny hopsage (Gray spinosa), and black greasewood are also browsed
[2,28].  Four-wing saltbush (Atriplex canescens) is heavily used in
western Nevada [89].  In Butte County, Idaho, winterfat comprised 41
percent of black-tailed jackrabbits' annual diet.  Fourteen percent was
composed of grasses, with most grass consumption in March and April
[36].  Russian-thistle (Salsola kali) is an important forb diet item.
Needle-and-thread grass (Stipa comata) and Indian ricegrass (Oryzopsis
hymenoides) are preferred grasses [2].  Other preferred native grasses
include Sandberg bluegrass (Poa secunda) and bluebunch wheatgrass
(Pseudoroegneria spicata) [56].  Where available, crested wheatgrass
(Agropyron desertorum and A. cristatum) and barley (Horeum vulgare) are
highly preferred.  Cheatgrass (Bromus tectorum) use is variable:  It
comprised 45 percent of the April diet on two southern Idaho sites [28],
but black-tailed jackrabbit on an eastern Washington site did not use it
[11].

Warm Desert:  Mesquite (Prosopis spp.) [29] and creosotebush (Larrea
tridentata) [57,81] are principle browse species.  Broom snakeweed
(Gutierrezia sarothrae) and Yucca spp. [49] are also used.  In honey
mesquite (P. glandulosa var. glandulosa) communities in New Mexico,
overall black-tailed jackrabbit diet was 47 percent shrubs, 22 percent
grasses, and 31 percent forbs [18].  Black grama, dropseed (Sporobolus
spp), fluffgrass (Erioneuron pulchellum), and threeawns (Aristida spp.)
are the most commonly grazed grasses [18,29,82].  Leather croton (Croton
pottsii), silverleaf nightshade (Solanum alaeagnifolium), desert
marigold (Baileya multiradiata), wooly paperflower (Psilostrophe
tagetina), and globemallow (Sphaeralcea spp.) are important forbs,
although many forb species are grazed [82].  Opuntia spp., saguaro
(Carnegiea gigantea), and other cacti are used throughout the year but
are especially important in dry seasons as a source of moisture [70].


PREDATORS : 
Black-tailed jackrabbit is an important prey species for many raptors
and carnivorous mammals.  Nydegger and Smith [60] rated black-tailed
jackrabbit and Townsend's ground squirrel (Spermophilus townsendii) as
the two most important prey species on the Snake River Birds of Prey
Study Area.  Hawks preying on black-tailed jackrabbit include the
ferruginous hawk (Buteo regalis) [5,45,47,85], white-tailed hawk (B.
albicaudatus) [66], Swainson's hawk (B. swainsoni), and red-tailed hawk
(B. jamaicensis) [47].  Janes [47] reported black-tailed jackrabbit as
the primary prey of Swainson's, red-tailed, and ferruginous hawks on
Idaho and Utah sites.  Other raptors consuming black-tailed jackrabbit
include the great horned owl (Bubo virginianus), burrowing owl (Athene
cunicularia), golden eagle (Aquila chrysaetos), and bald eagle
(Haliaeetus leucocephalus) [37,90].  Nydegger and Smith [60] reported a
significant correlation between golden eagle production and black-tailed
jackrabbit productivity on the Snake River Birds of Prey Study Area.  In
Colorado and southeastern Wyoming, black-tailed jackrabbit constituted 9
percent of nesting bald eagle's diet [51].  Jackrabbits (Lepus spp.) and
cottontails (Sylvilagus spp.) combined formed 9 percent of the diet of
bald eagles wintering on National Forests in Arizona and New Mexico
[41].

Mammalian predators include coyote (Canis latrans), domestic dog (C.
familiaris), red fox (Vulpes vulpes), common gray fox (Urocyon
cinereoargenteus), American badger (Taxidea taxus), mountain lion (Felis
concolor), housecat (F. catus), and bobcat (Lynx rufus) [24,39,68].  In
many areas, black-tailed jackrabbit is the primary item in coyote diets
[1,325,45].  It is locally and regionally important to other mammalian
predators.  One study [35] found that jackrabbits (Lepus spp.) made up
45 percent of the bobcat diet in Utah and Nevada.  Another Utah-Nevada
study [61] found that jackrabbits were the fourth most commonly consumed
prey of mountain lion.

Rattlesnakes (Crotalus spp.) and garter snake (Thamnophis sirtalis) prey
on black-tailed jackrabbit young [54,81].  Raccoon (Procyon lotor) and
striped skunk (Mephitis mephitis) may also capture young [81].

Humans hunt black-tailed jackrabbit for food and hunt, trap, or poison
it as a pest species [24].


MANAGEMENT CONSIDERATIONS : 
Black-tailed jackrabbit populations undergo periodic peaks and lows
every 3 to 10 years [18,19,24].  Northern Utah populations, for example,
reached a peak density of 71.4 black-tailed jackrabbits/sq km in 1970,
declined to a low of 47.1 black-tailed jackrabbits/sq km in 1972
(Stoddart in [85]), and peaked to approximate 1970 levels in 1979 [88].
Large populations can overgraze ranges and depradate croplands and
conifer plantations [8,13,24,39,81].  Black-tailed jackrabbit control
methods are reviewed in several publications [26,39,50].

Range:  When populations are between peaks, black-tailed jackrabbit
presence may complement livestock grazing.  Daniel and others [18,19]
reported that at moderate stocking rates and average black-tailed
jackrabbit numbers, there was little competition for forage between
cattle and black-tailed jackrabbit on a Chihuahua Desert
creosotebush-honey mesquite rangeland.  The black-tailed jackrabbit
browsed shrubs such as creosotebush that the cattle found unpalatable.
In addition, the black-tailed jackrabbit consumed native poisonous
plants such as locoweed (Astragulus spp.), desert marigold, and wooly
paperflower, thereby reducing poisonous plant cover.  Thirty-six percent
of their total diet was composed of plants poisonous to cattle.  Daniel
and others [18] also found that black-tailed jackrabbit densities were
significantly (p<0.10) higher on rangeland in fair condition than on
good condition rangelands.  They suggested that maintaining rangelands
in good to excellent condition may be the best way to control
black-tailed jackrabbit populations.

Black-tailed jackrabbit populations in some areas of the Great Basin
have been declining for 20 to 25 years.  There has been an attendant
population decline of some raptor species including ferruginous hawk
[85] and golden eagle [60].  See HABITAT RELATED FIRE EFFECTS for
further details.

Black-tailed jackrabbit browse saltcedar (Tamarix ramosissima).  It is
apparently the only vertebrate herbivore in the United States to do so
[83].

Seeds of several plant species are dispersed in black-tailed jackrabbit
feces including dropseeds (Sporobolus spp.) [19] and prickly pear
(Opuntia spp.) [69].

Timber:  In coniferous forests, management practices that reduce edge
also reduce black-tailed jackrabbit populations.  Roads, skid trails,
and patchy canopy cover have been found to increase populations [39].

Lagomorphs can reduce conifer seedling survival.  Lagomorph damage to
young conifers can be confirmed by examining injured trees.  Because
they clip trees at an angle with sharp incisors, lagomorphs leave
smooth, oblique cuts on branchs and twigs.  Lacking sharp incisors, deer
(Odocoileus spp.) and elk (Cervus elaphus) leave jagged tears.  Clean
branch cuts and fecal pellets, which jackrabbits and rabbits often drop
at feeding sites, signal lagomorph damage [39].

Human Health:  The black-tailed jackrabbit is a reservoir for several
diseases transmittable to humans including tularemia, bubonic plague,
and Lyme disease [24,53,81].


REFERENCES : 
NO-ENTRY

Related categories for Wildlife Species: Lepus californicus | Black-Tailed Jackrabbit