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General Information

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The Kangaroo rat is classified as a Heteromyid rodent and is actually more closely related to squirrels than rats or mice (USWF 1997). There are 23 known species of kangaroo rats (Howard 1994) that are very similar down to the small details of their internal structure (USWF 1997). Kangaroo rats are nocturnal creatures that often live in dry and desert environments (Smithsonian Institution Press 1999).

Physically, kangaroo rats are four-toed endotherms (Smithsonian Institution Press 1999) that have large hind legs, small front legs and a relatively large head (USWF 1997). Adult kangaroo rats weigh in the area of 70 to 170 g (Nader 1978). The tail of the Kangaroo rat is longer than its head and its body (Smithsonian Institution Press 1999). An important physical feature of the kangaroo rat is its external fur lined cheek pouches which they use to store seeds while foraging (USWF 1997). Coloration for different kangaroo rat species can vary from pale cinnamon buff to a dark gray (Howard 1994). The Banner-tail kangaroo rat has a body length of 6 inches and a tail with a white tip which is 8 inches in length (Howard, 1994) and is one of the largest species of kangaroo rat. The Merriam kangaroo rat is slightly smaller in size than the Banner-tail at a total length of around 250mm ( Davis 1997). In all kangaroo rat species there is dimorphism between the sexes in that all the males are larger than the females (Bradley et al. 1971).

Kangaroo rats live in burrow systems that they use mainly for protection and rearing of young. When they are not in their burrows kangaroo rats spend a good deal of time defending their home range and foraging. When they are above ground, they exhibit “fleet footedness”, or jumping behavior (USWF 1997). The adaptation for strength in jumping gives kangaroo rats that forage for seeds over wider areas a selective advantage over their competitors (USWF 1997). Another behavior that kangaroo rats commonly engage in is “dust baths” or “sun bathing” near their burrow entrance. The same kangaroo rats will return to the same dust bath over and over again on different days and time . Kangaroo rats use this as a method of heat regulation which allows them to live in their desert environment (California EPA Department of Pesticide Protection 2002). Engaging in this behavior allows the kangaroo rat to expend as little water as possible on heat regulation, so they will use the dust baths as coat maintenance (Protection 2002). This sun bathing activity is also thought to be a form of territorial defense because it spreads olfactory signals to predators (Ward 1986).

Kangaroo rats have been suggested to use the “time minimizer” feeding strategy. In this strategy the time minimizer rarely actively searches for food, rather they encounter it while performing other activities such as defending a territory, monitoring for predators or searching for mates. The idea behind this theory is that increasing foraging activity past their current level would actually reduce fitness because it would reduce survivorship. Schroder hypothesizes that the kangaroo rat, specifically the Banner-tail kangaroo rat, falls into this feeding strategy (Schroder 1979). Kangaroo rats who efficiently gather a highly visible resource within a small, well defined home range fit the profile for this strategy. Also, since the kangaroo rat would have to spend more time outside of its burrow, and thus exposed to its predators, in order to spend more time foraging this theory would seem to prove true for the kangaroo rat.

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