P2.13  Sunday, Jan. 5 15:30  Stress affects the behavior of urban and montane populations differently HOPE, S.F.*; ABOLINS-ABOLS, M.; KETTERSON, E.D.; The College of New Jersey; Indiana University; Indiana University hopes1@tcnj.edu

The trade-off between self-maintenance and reproduction is important for animals that must partition limited resources to maximize fitness. Stress, reproductive opportunities, and resource availability often differ between habitats and populations, thus individuals are required to alter their resource allocation to competing functions. Behavior can serve as a mechanism to enable allocation decisions and as an indicator of altered allocation. We experimentally compared birds for their territorial behavioral response to an acute stressor in two Oregon junco (Junco hyemalis thurberi) populations living in two different habitats – urban and montane. Urban birds are known to be less responsive to stress and to allocate more to reproduction. On day 1, birds from both experimental and control groups in both habitats experienced a simulated territorial intrusion (STI). In the experimental group, the STI was followed by capture and handling; in the control group there was no capture or handling. On day 2 both groups experienced a second STI. If stress on day 1 has a negative impact on reproduction (aggression), we predicted that birds from the experimental group would be less aggressive than controls on day 2. If the impact of stress varies with habitat, we predicted a greater effect in the montane population, since montane junco populations are known to be more responsive to stressors. We found that stress on day 1 negatively affected activity and distance to the intruder on day 2 in the montane population but not in the city population, indicating that acute stress can vary in its effect on behavior in populations inhabiting different habitats. We conclude that variation in the trade-off between stress and reproduction may be manifested in a behavioral mechanism related to allocation decisions.