[5][6] The pygmy rabbit differs significantly from species within either the Lepus (hare) or Sylvilagus (cottontail) genera and is generally considered to be within the monotypic genus Brachylagus.

The pygmy rabbit was first described by Clinton Hart Merriam in 1891, as Lepus idahoensis; the type specimen, in winter pelage, had been collected in the Pahsimeroi Valley the previous autumn.

[1] The pygmy rabbit is the world's smallest leporid,[7][8][9][10] with adults weighing between 375 and 500 grams (0.827 and 1.102 lb), and having a body length between 23.5 and 29.5 centimeters (9.3 and 11.6 in); females are slightly larger than males.

The range of the pygmy rabbit includes most of the Great Basin and some of the adjacent intermountain areas of western North America.

[11] Pygmy rabbits are found in southwestern Montana from the extreme southwest corner near the Idaho border north to Dillon and Bannack in Beaverhead County.

[15] A crossbreeding program conducted by the Oregon Zoo, Washington State University, and Northwest Trek is attempting to preserve the genetic line by breeding surviving females with the Idaho pygmy rabbit.

Young from early litters grow larger due to a longer developmental period prior to their first winter.

[11] Pygmy rabbits are normally found in areas on deep soils with tall, dense sagebrush which they use for shelter and food.

[11] Dense stands of big sagebrush along streams, roads, and fencerows provide dispersal corridors for pygmy rabbits.

[19] In areas where soil is shallow pygmy rabbits live in holes among volcanic rocks, in stone walls, around abandoned buildings, and in burrows made by badgers (Taxidea taxus) and marmots (Marmota flaviventris).

[11][12] Pygmy rabbits are seldom found in areas of sparse vegetative cover and seem to be reluctant to cross open space.

[20] Some woody species found on sites inhabited by pygmy rabbits in southeastern Idaho include big sagebrush, antelope bitterbrush (Purshia tridentata), threetip sagebrush (A. tripartita), low rabbitbrush (C. viscidiflorus), gray horsebrush (Tetradymia canescens), and prickly phlox (Leptodactylon pungens).

Grasses and forbs include thick spike wheatgrass (Elymus lanceolatus), plains reedgrass (Calamagrostis montanensis), sedges (Carex spp.

), needle-and-thread grass (Stipa comata), western yarrow (Achillea millefolium), rosy pussytoes (Antennaria microphylla), milkvetch (Astragalus spp.

[11][13][20][24] In Idaho, Gates & Eng (1984)[24] found that shrubs contributed 85.2% (unweighted mean) of pygmy rabbit diets from July to December.

Big sagebrush was the most important shrub in the July to December diet (54.2%), followed by rubber rabbitbrush (Chrysothamnus nauseosus, 25.8%) and winterfat (Krascheninnikovia lanata, 4.6%).

Grass and forb consumption was relatively constant throughout the summer (39% and 10% of diet respectively) and decreased to a trace amount through fall and winter.