Sex differences in agonistic behavior of Merriam's kangaroo rats (Dipodomys merriami)

Agonistic behavior of heteromyid rodents has been studied using staged enco unters in the laboratory, but there have been no previous attempts to lest for a linear dominance hierarchy among individuals of the same species. Dom inance hierarchies are important in learning about sociality, priority of a ccess to resources and consequences for individual variation in fitness. We used standard laboratory methods to assess agonistic be havior of Merriam' s kangaroo rats, Dilodomys merriami. Males exhibited a dominance hier archy that was strongly linear. Dominance rank was not correlated with body mass , but dominant males lost greater percentages of their body mass during tri als than did subordinate males, Males dominated females and females showed little agonistic behavior in intrasexual trials. The linear dominance hiera rchy among males may have reflected individual variation in aggressive tend encies, but dominance rank was not correlated with individual variation in total amounts stored or proportions of seeds larderhoarded in food-hoarding trials. Different patterns of individual variation in males and females ar e promising topics for future research.