Meeting Abstract

P2.110  Friday, Jan. 4  Plasticity of foraging strategies in soricid shrews: A model for behavioral stress response SWEENEY, M.J.**; YOUNG, R.L.; BADYAEV, A.V.; University of Arizona; University of Arizona; University of Arizona mjs84@email.arizona.edu

Organismal stress, such as extreme environmental conditions or malnutrition, can often disrupt behavioral, morphological and nuero-endocrinological systems. Behavioral adjustment (e.g., avoidance, activity regulation, and foraging preference) may sometimes provide an immediate and effective response to stress for an individual. When considering food resource limitations, adjustments in foraging behavior can allow an organism to exploit less preferred but more readily available food sources. However, behavioral modifications are constrained by factors such as diet breadth, food availability, and metabolic and nutritional needs. In insectivorous shrews, huge metabolic requirements necessitate continuous foraging. While almost compulsorily opportunistic, interspecific diet preferences are thought to exist as a result of biomechanical limitations and variation in foraging strategy. Here, we examine the influence of organismal stress on foraging behavior through the evaluation of stomach contents of several soricid shrew species across different populations experiencing distinct levels of environmental stress. Contents of stomachs were evaluated in terms of prey type, hardness and proportion of insect exoskeleton cuticle to soft tissue ingested. Stomach analysis was compared to levels of historic and immediate stress by measuring both fluctuating asymmetry (i.e., deviations from bilateral symmetry) in mandible growth and intestinal-endoparasite loads, respectively. We discuss the implications of these results for both the evolution of interspecific diet specialization, and for behavioral plasticity as a strategy for stress avoidance.