When they are active above ground they move about within their territory and attempt to fill their cheek pouches with seeds and plant material. When their cheek pouches are full they retreat to their burrows where they disgorge the seeds they have collected. The bulk of their diet consists of the seeds of desert and grassland plants. MKR rarely drink water. They obtain water through metabolic processes augmented by the moisture content of their food.
Kangaroo rats are a common prey items for many other desert animals.
Typical predators of the MKR include barn and great horned owls, coyotes, foxes, badgers, bobcats, and several snake species including sidewinders and glossy snakes. In general we have not caused adverse impact to the Merriam's kangaroo rat through most of its range. However, in southern California one subspecies of MKR is at risk due primarily to urban development including construction of dams and alteration of hydrologic regimes throughout its range. Once common on alluvial plains in the washes of San Bernardino and Riverside counties, the United States Fish and Wildlife Service listed the San Bernardino kangaroo rat as endangered in 1998. Chew, R.M., Butterworth.