The majority of kangaroo rats eat mesquite beans and a variety of seeds from desert grasses. The seeds they eat include those from creosote, bush, purslane, ocotillo and grama grasses. Some kangaroo rats also eat green vegetation and insects.
Kangaroo rats forage for seeds and store the ones they find in pouches located inside of their cheeks, before taking the seeds back to their storage cache. Kangaroo rats store their seeds in caches to limit the amount of time that they are away from their burrows; this reduces their vulnerability to the harsh conditions of the desert heat, and limits their exposure to predators. Different species of kangaroo rats use different methods to create their food caches. They do this in order to make the most of the food sources that are available, while competing with other species of kangaroo rats for the available resources.
For example, the banner-tailed kangaroo rat and the Merriam's kangaroo rat have overlapping ranges where they both coexist. Banner-tailed kangaroo rats use a cache method called larderhoarding to create large hoards of seeds within the mounds they live in. This works well because this species is larger and sedentary, but their size makes it easy for them to defend their hoards from other rodents.
Merriam's kangaroo rats use a hoarding method known as scatterhoarding to create numerous small caches of seed in shallow holes that they dig. The caches are typically created near the food source, allowing the rats to harvest more food and reduce travel. The caches are also spread across a wide area to minimize theft by other rodents.