are able to concentrate their urine to a viscous consistency which further reduces water loss. Under extreme conditions, some are able to aestivate in chambers under ground. Kangaroo rats have large hind feet with long metatarsals and no first digits. With these they bound around not using their fore feet at all for locomotion. Pocket mice are smaller and can also move with leaps but they normally run around on four limbs. Members of the genus Heteromys, the spiny pocket mice, move around on all fours and do not leap at all. Ecology Kangaroo rats and pocket mice form a part of the diet of many predatory creatures. They are eaten by foxes, coyotes, snakes and birds. They have acute hearing and can detect the approaching swoop of an owl or the movements of a snake. Many can leap to avoid the predators as they seek the safety of their burrows. The largest kangaroo rats can leap in a single bound. In the Sonoran Desert there are many closely related species of heteromyid mice and rats. Each has its own niche in the environment which means that they do not unnecessarily compete with each other for the limited available resources. Bailey's pocket mouse climbs into plants and bushes in order to find seeds and berries still attached to the plant. It is the only species able to eat the wax found inside the seeds of the jojoba plant. Merriam's kangaroo rat primarily moves rapidly from one bush to another gathering seed but overlooking anything lying on the desert floor. The desert pocket mouse forages across the open desert floor and gathers seeds that have fallen to the ground. Taxonomy Family Heteromyidae Subfamily Heteromyinae — spiny pocket mice Genus Heteromys Panamanian spiny pocket mouse, Heteromys adspersus Trinidad spiny pocket mouse, Heteromys anomalus Southern spiny pocket mouse, Heteromys australis Overlook spiny pocket mouse, Heteromys catopterius Desmarest's spiny pocket mouse, Heteromys desmarestianus Gaumer's spiny pocket mouse, Heteromys gaumeri Goldman's spiny pocket mouse, Heteromys goldmani Mexican spiny pocket mouse, Heteromys irroratus Nelson's spiny pocket mouse, Heteromys nelsoni Cloud-dwelling spiny pocket mouse, Heteromys nubicolens Paraguaná spiny pocket mouse, Heteromys oasicus Mountain spiny pocket mouse, Heteromys oresterus Painted spiny pocket mouse, Heteromys pictus Salvin's spiny pocket mouse, Heteromys salvini Jaliscan spiny pocket mouse, Heteromys spectabilis Ecuadoran spiny pocket mouse, Heteromys teleus Subfamily Dipodomyinae — kangaroo rats and mice Genus Dipodomys — kangaroo rats Agile kangaroo rat,