Kangaroo Rat Facts
Explore this page to find out more about kangaroo rat ecology! Scientists refer to any species within the genus Dipodomys as a kangaroo rat. Kangaroo rats are a uniquely North American group of rodents. A few million years ago, as much of the western part of North America dried up and became desert-like, kangaroo rats evolved and diversified across the landscape. There are about 20 species spread across desert-like habitats in western North America, from central Mexico to southern Canada. There are good pages on Wikipedia for kangaroo rats. See the page on Dipodomys genus for links to individual species, and the page on Heteromyidae for information on the whole kangaroo rat family.
For the Love of Seeds
Kangaroo rats are all nocturnal and largely herbivorous granivores: they mainly eat seeds. Like their cousins, the pocket gophers, they have large fur-lined cheek pouches for carrying around big quantities of seeds. A kangaroo rat with its cheeks stuffed full of seeds looks pretty funny, but it’s an effective way for an animal with no fingers to carry lots of food. Plus, because the pouches are outside the mouth, they can keep their mouths shut and save valuable water by not moistening seeds with their own saliva.
Kangaroo rats will go to great lengths to find and store seeds and other plant parts. Once they find seeds and stuff their cheeks full, they carry the seeds back to their burrow, where some are eaten and others are saved for later. They occasionally eat green sprouts, flowers, and other vegetation, but most species eat mostly seeds, most of the time.
For the Love of Seeds
Kangaroo rats have a number of adaptations for living in hot and dry deserts. Here are some of the coolest (pun intended!):
No need to drink or pee. Kangaroo rats will drink water if they find it, or lick up drops of dew, but they go for months without needing to drink. Kangaroo rats get most of their water from eating seeds and other plant parts. They excrete only tiny droplets of hyper-concentrated urine very occasionally, so they don’t really pee.
Efficient breathing. Kangaroo rats have long snouts that allow them to resorb water from their exhaled breaths within their nasal cavity. This means they lose less water than other animals when exhaling.
Burrow living. You don’t have to go far beneath the desert surface to reach more comfortable temperatures. Kangaroo rats are good diggers, and build burrows that allow them to spend lots of time in relatively cool underground chambers.
Good grooming. Kangaroo rats have oily coats that prevent water loss. They maintain their coats with hygienic dust baths -- rolling around in fine dirt or sand helps them keep the proper level of oil in their fur.
Kangaroo rats can be among the most abundant small mammals in deserts. Any naturalist who spends time in the deserts of North America will almost immediately notice their presence. Because they are so successful, they occur at high densities and their burrows are found all over. Some of the bigger species build large, conspicuous mounds with a network of tunnels. Because they are highly abundant, voracious consumers of seeds, and prolific builders of mounds and burrows, kangaroo rats are keystone species. This means that they have an inordinately important role in desert ecosystems. Scientists have found that if you experimentally exclude kangaroo rats from an area of desert, the vegetation community, the cycling of nutrients, and the presence of other animals in the ecosystem all changes, and it changes pretty quickly. Kangaroo rats are clearly integral to the stability of desert ecosystems, and we should be careful about protecting them. Although many kangaroo rats are still abundant in well-protected deserts, some species are rare and endangered, and as a group they seem pretty susceptible to the impacts of roads and other human development.
Jumping and Hearing
Kangaroo rats have a unique look—large haunches, huge hind feet, and bulbous heads. This morphology is all related to their specialized anti-predator jumping. Most rodents are quadrupeds (move on four limbs), but kangaroo rats are bipedal hoppers. This morphology probably evolved so that they could use evasive jumping to avoid predators. As shown in our videos, their incredibly powerful hind limbs and long legs give them explosive leaping ability. But how is kangaroo rat reaction time so fast? It probably comes down to super-sensitive hearing. The kangaroo rat head is bulbous because they have huge, hollow chambers in their skull which transmit low-frequency sounds better, making their hearing much more sensitive than most animals. It appears as if the faint whoosh of sound made by a striking snake or swooping owl is enough to trigger a powerful evasive leap that, more often than not, sends them flying clear of the attacking predator.
Jumping and Hearing
Kangaroo Rat Behavior
Kangaroo rat behavior is fascinating, and there’s a relatively large body of scientific literature on it. But we can summarize some of it by imaging a day in the life of a typical kangaroo rat.
Once Upon A Time,
There was a kangaroo rat named Kangy...