Kangaroo Rats Pocket Mice and Kangaroo Mice: Heteromyidae

Physical characteristics: Giant kangaroo rats are the largest members of heteromyids. They have long and powerful hind limbs that are used for hopping, and small and relatively weak front limbs that are used for digging. These animals have very long tails that are used for balance. Their dark tail has white lines along either side. They have large eyes, small rounded ears, and a somewhat rounded body. Their coat is sandy-colored with a white underside and a white stripe across the hindquarters. Adults are 12.3 to 13.7 inches (31 to 35 centimeters) long and weigh between 3.0 and 6.3 ounces (93 and 195 grams).

Geographic range: Giant kangaroo rats are found in San Joaquin Valley, California.

Habitat: They inhabit arid grasslands that contain sandy soils and are sparsely populated by desert shrubs.

Giant kangaroo rats use their strong hind limbs to hop around. They can jump up to 6 feet (2 meters) to escape from a predator. (© Richard R. Hansen/Photo Researchers, Inc. Reproduced by permission.)

Diet: Their diet consists of seeds, which are first stored in burrows. Sometimes seed heads are cured, preserved, in surface caches. They also eat insects and other vegetation.

Behavior and reproduction: Giant kangaroo rats are nocturnal animals, hiding in their burrows during the hottest parts of the day. Burrows are usually shallow tunnels that contain larger chambers, one that acts as a nest and the others used to store food. They are usually found alone, and move by hopping on their back legs. Their back, hind, legs let them jump over 6 feet (2 meters) when escaping predators. Their front limbs are smaller and used only for digging. They defend their territory, but live peacefully with their close neighbors.

Both sexes drum their hind feet in order to tell visitors to stay away, or to tell other giant kangaroo rats that predators, such as snakes and kit foxes, are around. Males drum their feet while competing with other males for the right to mate with a mature female. This mating sound may include up to 300 individual thumps that are repeated many times. The breeding season is from January to May. Females have more than one breeding cycle per year, and have an average of three breeding cycles in a breeding season. The gestation, pregnancy, period is thirty to fifty-five days. Typically, females are able to breed again three days after giving birth. Young are able to breed after only two to three weeks of being born.

Giant kangaroo rats and people: Giant kangaroo rats are considered keystone species.

Conservation status: Giant kangaroo rats are listed by the IUCN as Critically Endangered. They are also considered endangered by the California Fish and Game Commission and the U.S. Fish and Wildlife Service. Their populations have drastically decreased due to habitat loss as deserts are converted to agricultural lands. They no longer occupy over 95 percent of their former habitat, but are protected within the Carrizo Plain Natural Heritage Reserve and a number of federal lands. ∎