Meeting Abstract

20.9  Jan. 5  Range Expansion and Neuroendocrine Modulation in Puget Sound White-Crowned Sparrows (Zonotrichia leucophrys gambelii) DAVIS, J.E.*; ADDIS, E.A.; O’BRIEN, S.; WINGFIELD, J.C.; University of Washington jedavis@u.washington.edu

The Puget Sound white-crowned sparrow (Z. l. pugetensis) has a historic breeding distribution limited to the Pacific coast of Oregon and Washington. In contrast, Gambel�s white-crowned sparrows (Z. l. gambelii) breed predominantly in Alaska and northern Canada south to several high altitude sites in the northern Cascade Mountains of Washington State. Previous studies have shown that gambelii at northern and southern parts of their range express a highly modulated stress response during the breeding season, such that subsequent corticosterone increase is higher during the territory and mate selection, and lower during parental care. This may be an adaptation to the short-breeding season and high cost/benefit ratio associated with extreme environments, allowing flexibility in coping behavior early in the breeding season while making birds relatively resistant to stress-induced reduction in parental behaviors. Historic accounts have shown little or no overlap in the breeding territories of gambelii and pugetensis. However, climate change and the human disturbance of previously forested areas seem to have provided an opportunity for pugetensis to colonize alpine habitats thus bringing these two subspecies into contact. This range expansion into alpine habitat also presents pugetensis with new challenges, including extremes of weather, limited food sources, and a shortened optimal breeding period. In addition, several of these recent high-altitude populations display gambelii-like morphological and behavioral traits, indicating potential hybridization. The distribution, morphology, behaviors and modulation of the adrenocortical responses to stress observed in several high and low altitude breeding populations is presented.