BARBER, A. M.; University of Nevada, Reno: Hormonal basis of seed-caching behavior and spatial memory ability in Merriam�s kangaroo rats

Merriam�s kangaroo rats (Dipodomys merriami) utilize two main strategies to store seeds for future consumption: scatterhoarding and larderhoarding. Scatterhoarding is the placement of seed caches that are dispersed in many locations within an animal�s home range, whereas larderhoarding is the storage of seeds that are kept in a centralized location (e.g. within a burrow). Data from both laboratory and field studies demonstrate that seed-caching behavior is repeatable within individuals, and the proportion of seeds stored in scatterhoards shows significant variation among individuals. Measurements of fecal corticosteroid indicate that these hormone levels are inversely correlated with proportion of seeds scatterhoarded in the field. Memory of seed cache locations plays an important role for individuals that utilize a strategy of predominately scatterhoarding. I tested spatial memory ability in an associative learning test for individuals exhibiting different foraging strategies. Memory ability may be related to foraging strategy; these behaviors could be mediated by corticosteroid levels. Measures of repeatability in hormone profiles and behavior suggest consistency within seasons in both physiology and behavior, which may underlie the expression of particular behavioral strategies.