White-tailed jackrabbit

The white-tailed jackrabbit is a large species of hare and the largest species called "jackrabbit", although 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 due to pregnancy in females, but decrease due to the stresses of reproductive competition in males. 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. At the northern most 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, grey ears with black tips which are chestnut brown and white on the inside; 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. They generally make no sound, but will emit a shrill scream if they are injured or caught.