COMPETITIVE ENVIRONMENT AFFECTS FOOD-HOARDING BEHAVIOR OF MERRIAM'S KANGAROO RATS (DIPODOMYS MERRIAMI)

Abstract

North American desert rodents in the family Heteromyidae live in an unpredictable environment characterized by extremes in temperature and food availability; therefore, the ability to hoard food is a vital adaptation. Although much laboratory research has investigated food-hoarding tactics of heteromyid rodents, data from natural systems are scarce. We used a combination of fluorescently labeled seeds and observations of focal individuals to evaluate food-hoarding behavior in wild Merriam’s kangaroo rats (Dipodomys merriami) living in different competitive environments. There was considerable individual variation within populations in the tendency to larderhoard seeds in a burrow versus scatterhoard seeds in widely dispersed locations. However, Merriam’s kangaroo rats living in a system where competitors were predominately conspecific scatterhoarded more than those living in a system where conspecifics were less abundant and heterospecific competitors also were present. Also, pilferage was more common between Merriam’s kangaroo rats than across species. Comparisons of food hoarding between communities with different species composition indicate that intraspecific variation in behavior may be associated with variation in competitive environments.