Their total length is 18 to 25 inches (465-630 mm). They have long-black tipped ears, 4 to nearly 7 inches (99-131 mm) long. Their back is gray to blackish, sides are gray, and whitish underneath. They don’t change color in the winter. Their hind feet are large. They weigh 4 to 8 pounds (1.8-3.6 kg).
From Pacific Coast, east to Missouri and Arkansas, and from Washington and Idaho, south to central Mexico. They are more abundant and widespread compared to the white-tailed jackrabbit.
Inhabits open plains, fields and deserts, and open country with scattered thickets or patches of shrubs. In Idaho, found in lower-elevation rangeland associated with shrub steppe communities of southern part of state; adapts well to areas of agricultural development.
In summer, forages on grasses, forbs , crops, and hay; in winter, eats buds, bark, and leaves of woody plants. Southeastern Idaho studies reported winterfat, green rabbitbrush, cheatgrass, crested wheatgrass, and perennial grasses were primary foods. This species obtains water from vegetation and re-ingests soft fecal pellets produced while resting.
Active throughout year. Primarily crepuscular and nocturnal . Rests by day in shallow depression (form). May travel up to 1.6 km from daytime retreat to night feeding area. May gather in large group to feed. In northern Utah study, home range varied from less than 1 km2 to 3 km2; in Idaho study, home range was 12.5-18.2 km2. Populations are known to fluctuate markedly, slowly reaching peak over several years, and falling off rapidly in several weeks or months (in Idaho, population peaks at 10-yr cycle). Populations may increase or decrease with grazing. Both raptors and carnivorous mammals respond numerically and functionally to changes in jackrabbit abundance. Some research suggests there may be a connection between their population fluctuations and coyote population fluctuations. This species adapts better to agriculture than the white-tailed jackrabbit, thus their populations are often higher in Idaho, especially historically. They are susceptible to diseases such as tularemia , which can decimate a population, as well as tick fever.
Breeding period may extend from late winter to late summer (in southeastern Idaho study, length of breeding season was variable and not affected by weather). gestation lasts 41-47 days. Females produce 1-4 litters of 1-8 (usually 2-4) precocial young each year (in eastern Idaho study, estimated production was 2.5 litters/yr). Their growth is rapid, young are nearly as large as adults in 10 weeks.
Important State References:
Johnson, D.R. and J.M. Peek. 1984. The black-tailed jackrabbit in Idaho: life history, population dynamics, and control. Coop. Extens. Service, Univ. Idaho, College Agricult. Bull No. 637, Moscow. 16pp.