White-tailed jackrabbit
The white-tailed jackrabbit (Lepus townsendii), also known as the prairie hare and the white jack, is a species of hare found in western North America. Like all hares and rabbits, it is a member of the family Leporidae of order Lagomorpha. It is a solitary individual except where several males court a female in the breeding season. Litters of four to five young are born in a form, a shallow depression in the ground, hidden among vegetation. This jackrabbit has two described subspecies: L. townsendii townsendii occurring west of the Rocky Mountains and L. townsendii campanius occurring east of the Rocky Mountains.[2]
"White jack" redirects here. For the naval flag, see white ensign.Description[edit]
The white-tailed jackrabbit is a large species of hare and is the largest species called "jackrabbit". (Two larger hares, the Arctic and Alaskan hares, are found further north in North America). This jackrabbit has an adult length of 56 to 65 cm (22 to 26 in), including a tail measuring 6.6 to 10.2 cm (2.6 to 4.0 in), and a weight between 2.5 and 4.3 kg (5.5 and 9.5 lb). From winter to spring, weight tends to increase in females due to pregnancy, but decrease in males due to the stresses of reproductive competition. Thus, females in Iowa went from averaging 3,600 g (7.9 lb) in winter to 3,800 g (8.4 lb) in spring and males from averaging 3,400 g (7.5 lb) in winter to 3,100 g (6.8 lb) in spring.[3] At the northernmost extremity of its range, it can be almost twice as large as in the middle of its range. In Saskatchewan, rare specimens have been recorded over 9 kg (20 lb). It has distinctive large black-tipped grey ears that are chestnut brown and white on the inner surface, and the long, powerful hind legs characteristic of hares. The back, flanks and limbs are dark brown or greyish-brown and the underparts are pale grey. The ear, from the notch, measures from 10 to 11.3 cm (3.9 to 4.4 in) and the hindfoot measures 14.5 to 16.5 cm (5.7 to 6.5 in). The tail is white with a dark central stripe above. Females are slightly larger than males. In northern populations, this hare moults in the autumn and becomes white all over except for its ears.[4] They generally make no sound, but will emit a shrill scream if they are injured or caught.[5]
Ecology[edit]
White-tailed jackrabbits influence the composition of the turf through their selective grazing activities. They are important prey species for various mammalian predators. Red (Vulpes vulpes) and grey foxes (Urocyon cinereoargenteus) occasionally capture one, though not many large adults. They are perhaps most important prey for mid-sized carnivores such as the American badger (Taxidea taxus), the coyote (Canis latrans), and the bobcat (Lynx rufus) and small supplemental prey for larger ones such as the mountain lion (Puma concolor) and the gray wolf (Canis lupus).[9] Snakes sometimes attack them (usually young ones) and bird predators include eagles, hawks, and owls. Golden eagles (Aquila chrysaetos) and bald eagles (Haliaeetus leucocephalus) are the only avian predators large enough to regularly take full-grown white-tailed jackrabbits, though ferruginous hawks (Buteo regalis) and great horned owls (Bubo virginianus) may occasionally take an adult, though these latter two species and other largish raptorial birds typically attack young.[10][11][12][13] They attempt to evade detection by crouching in the vegetation where their cryptic colouration makes them difficult to observe. They may slink away, but if detected, they bound away at speed, adopting a zigzag course. They can run up to 55 km/h (34 mi/hr) and leap up to 5 m (16 ft).[5] They are also hunted and eaten by humans.[5]
Status[edit]
The white-tailed jackrabbit is assessed as being of "Least Concern" by the IUCN in its Red List of Threatened Species because it has an extensive range and is fairly common across most of its range. The population size may be declining slightly, but not at a rate that would justify listing this hare in a more threatened category.[2]
In Wyoming, however, it has become scarce in Grand Teton National Park, where it has not been seen recently.[2] Briefly reputed to have been extirpated in Yellowstone National Park, where it was at one time abundant,[14] it is now clear from observations, roadkilled specimens, and historical records that white-tailed jackrabbits are still present in the park.[15] The causes of the decline in populations in Wyoming is unclear.[2]