Kangaroo rats are medium-size rodents of the family Heteromyidae. Unlike their cousins the brown or Norwegian rats (Rattus norvegicus) and sewer rats, frequently found living in large groups in urban areas, the kangaroo rat is a solitary animal found only in the remote desert areas of the North American West and Southwest.
All 22 species of kangaroo rats are of genus Dipodomys. They are easily recognized by long fur-covered tails -- they're as long as one and a half times their body lengths -- and their long, broad hind feet. They're called kangaroo rats because they use their oversize hind feet to hop across the desert sands instead of scurrying like many rodents. Their tails are tufted at the end and help them keep upright while hopping. When pursued by predators, they can leap as far as 9 feet in a single bound. They range in size from 9 to 14 inches and are found in various shades of brown and cream. Average life span is 5 years in captivity. Because they are heavily preyed upon in their natural habitat, it is unlikely that most specimens survive that long in the wild.
Kangaroo rats live exclusively in the deserts of North America.They have several adaptations that allow them to thrive here where many animals can not -- in hot, dry, sandy areas with sparse vegetation and very little water. Their kidneys are designed to create concentrated urine so very little water is lost during urination. They have no sweat glands, so no moisture is lost to perspiration; and they have hair on the soles of their feet that protects their feet from hot surfaces and enables them to move easily over loose sand.
These little animals are perfectly adapted to the harsh realities of life in the desert. They use strong hind legs to dig burrows deep in the desert sand, away from the heat of the day. Once in the burrow, they use their legs to pack sand in the opening, sealing in the cool underground air. They are nocturnal, rarely leaving the protection of their burrows until the sun goes down. To aid them in their nocturnal lifestyle they have developed keen hearing and large eyes that enable them to see in almost complete darkness. They spend their evenings watching out for predators, including foxes, snakes and owls, and foraging for seeds, which they stuff into their cheek pouches to carry back to their burrows.
The mating season of the kangaroo rat runs from January to May, with a single female capable of bearing and raising as many as three litters per year. Once bred the female will carry her young for 32 days before giving birth to two to four pink, hairless, completely helpless babies. Amazingly, because of her body's adaptations to life in the desert, even with no water supply, a female kangaroo rat is able to get enough moisture from the seeds she eats to produce sufficient milk to support her rapidly developing offspring. The young begin to grow hair at 3 to 4 days; by 9 days of age they're able to be identified by gender. Males will have begun to form bulges at the bases of their tails, their testes. When they reach sexual maturity, their testes will be quite large and easily visible. By 4 weeks of age, the young look just like small adults and are are ready to leave the burrow. By 12 to 13 weeks, they are adults and leave their mother's territory to dig burrows of their own.
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Barbara Taliaferro is an animal enthusiast who lives in Ambler, Pa. She holds a Bachelor's Degree in Animal Science and has spent most of her life working with animals and the people who love them. She has been sharing her love and knowledge of animals through the written word since 2009.