RICHARDSON, Matthew; MOORE, Ignacio; SOMA, Kiran; FU-MIN, Lei; WINGFIELD, John: Stress in an unpredictable environment: Snow finches on the Tibetan Plateau

Studies of adaptations of hormone-behavior relationships to unpredictable environments have concentrated on the arctic. The arctic environment is characterized by an extremely rapid breeding season with limited chances to resume reproduction should a first opportunity fail. During this short breeding season, some avian species suppress their hormonal stress response (an increase in plasma corticosterone) in order to avoid the potential deleterious effects of stress on reproduction. We expanded our investigations of adaptations to extreme and unpredictable environments to high elevation sites where the breeding season is also short in duration and marked by unpredictable perturbation factors. The breeding season is very short at the three sites we visited (3300-4000 m altitude) on the Tibetan Plateau of western China, and comparable in length to the high arctic. We investigated the seasonal and sexual plasticity of the stress response in snowfinches. Free-living rufous-necked snowfinches ( Pyrgilauda ruficolis) and white-rumped snowfinches ( Pyrgilauda taczanowskii) were captured and serially bled to determine responsiveness of the hypothalamic-pituitary-adrenal axis. This was done during the breeding and non-breeding season. Within both snowfinch species, plasma corticosterone levels increased in response to the stress of capture during both the breeding and non-breeding season. While the stress responses were similar between the breeding and non-breeding seasons in both species, males tended to exhibit a greater increase in plasma corticosterone than females. We are expanding the study to other bird species breeding on the Tibetan Plateau.