Arizona-Sonora Desert Museum Digital Library

Distinguishing Features

The antelope jackrabbit is one of the largest hares in North America, weighing nine to ten pounds (4.5 kg). This jackrabbit's huge ears are edged in white. The large eyes are placed high and towards the back of its slightly flattened head, allowing it to see nearly 360 degrees as it watches for predators. The antelope jackrabbit is so named because it has a patch of white fur on its flanks that it can flash on one side or the other as it zigs and zags, running from a predator, much as the pronghorn antelope does.

Habitat

The antelope jackrabbit inhabits the drier areas of the desert, including creosote bush flats, mesquite grassland, and cactus plains into and beyond southern Sonora. It prefers open places with sparse grasses where it can see predators and flee if need be.

Feeding

• Diet: The rabbits and hares are herbivores, feeding on grasses, forbs, mesquite leaves and beans, and cacti (for moisture). Twigs nipped off by jacks have clean, slanted cuts. (Twigs browsed by deer look pinched off.)

• Behavior: The large antelope jacks can consume ¼ pound (118 g) of food per day.

Life History

Antelope jackrabbits are nocturnal, resting in the shade of a cactus or other plant during the day. They don't escape the heat by digging or borrowing burrows, and seldom get to drink water, so they must conserve energy and moisture by resticting their activities to the cooler hours of the day.

When a jack suspects a predator is nearby it often stands on hind legs to get a better view, then crouches down and freezes. If the predator gets too close the jack springs up, leaping away in 15 foot (4.6 m) bounds. After a few leaps the jack jumps even higher as it sails over bushes and other obstacles and tries to spot the predator. These hares can run up to 35 miles per hour (56 km/h) for up to ½ mile (.8 km)!

Jackrabbits breed throughout the year. Courtship is dramatic with chases, charges, leaps over each other, and sprayed urine. Six weeks later, one or two baby jacks weighing about ½ pound (230 g) each are born already furred and with their eyes open. The youngsters are precocial — able to move about shortly after birth — but may stay with the mother for several months. Jacks are very social. Large groups of twenty five or more congregate, especially on moonlit nights.

Of all the desert-dwelling mammals, the desert cottontail is probably the one you will see most frequently. Preyed upon by everything from snakes to coyotes to owls, most cottontails are killed within their first year. These rabbits have few defenses other than good eyesight, good hearing, and the ability to flee quickly. They compensate for heavy losses by reproducing at a prodigious rate. Female cottontails can breed at three months of age and have multiple litters in a year. Young stay at the nest for only about two weeks before venturing off. These reinforcements make for a fairly constant supply of cottontails.

Jack “rabbits” — they are actually hares— live in open areas with little cover; they rely on exceptional speed and great leaping ability to evade predators, but they also suffer predative losses.

In the field, size is an easy way to tell cottontails apart from jackrabbits. Cottontails are small, 1 to 2 pound (.45 to .9 kg) animals, while jacks are quite large, weighing up to 10 pounds (4.5 kg) and standing just under 2 feet (.6 m) tall. Cottontail babies (true rabbits) are born blind, naked, and helpless; but jackrabbit young (like all young of true hares) are born furred and with their eyes open; they can move around just a few hours after birth.