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Weird & Wonderful Creatures: Giant Kangaroo Rat

Photo Credit: U.S. Fish and Wildlife Service.

The giant kangaroo rat (Dipodomys ingens) lives in dry grasslands of the San Joaquin Valley, where the average rainfall is less than 15 cm (6 inches) a year. That means there is not a lot of water around to drink, particularly during the past few years, when California has suffered from an extreme drought. These rodents, like the other 21 species of kangaroo rats, have adapted to living in a dry climate by surviving on the water they extract from the seeds they eat.

This isn't the only way the kangaroo rats have become suited to survive in such a harsh climate, though. They have two other adaptations: First, their bodies have evolved so that their kidneys are highly specialized. These organs are able to concentrate waste materials in urine at a much higher level than most other animals' kidneys, which allows the kangaroo rat to urinate much less and, thus, retain more of the water they take in from their food. Second, they live alone in burrows below ground, which they close off during the day, and only emerge briefly at night after the air temperature has cooled off. This has allowed them to evolve away from the ways mammals traditionally have of cooling off—panting or sweating, both of which would require additional hydration.

The giant kangaroo rat has tan fur with a white belly and a white stripe across its hindquarters. Its tail is dark on top, but white on the bottom. It has small ears and large eyes.

While its name might make you think that this rodent is quite large, it is merely the biggest species of the kangaroo rats and is, in fact, quite small. It weighs about six ounces and its body is usually less than six inches long, with a tail that's even longer. The giant kangaroo rat does live up to the other half of its name, using its long hind legs to jump as its primary way of getting around. It can bound up to more than six feet in a single jump and can travel up to ten feet per second when necessary. It also uses its strong back legs to stamp out warnings to frighten away predators—foxes, badgers, coyotes, and snakes—and other giant kangaroo rats who might want to move in on its turf. Its front legs are short, and are better suited to digging and stuffing seeds in its fur-lined cheek pockets than to helping with locomotion.

The giant kangaroo rat, once abundant in the region, now appears on the endangered species list, thanks to agriculture, mining, and other industry infringing upon its desert home, reducing its territory to less than five percent of its original area. The Carrizo Plain National Monument is home to many of the remaining giant kangaroo rats, as well as 12 other endangered animals.

During non-drought years, scientists are able to monitor giant kangaroo rat populations from the air, where they can count the areas where each rat has chewed down the grasses around its burrow.

Are you interested in learning about other rodents? Listen to Science Updates on voles, wood mice, and white-footed mice

Would you like to learn more about endangered species? The lessons Endangered Species 1: Why Are Species Endangered? and Endangered Species 2: Working to Save Endangered Species are a good place to start. Science NetLinks also has resources on a number of other endangered species, including the golden lion tamarin, the northern hairy-nosed wombat, the African elephant, and the Panamanian golden frog.

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