Meeting Abstract
P1.47 Friday, Jan. 4 Adrenocortical Responses to Stress on the Leading Edge of a Northward Range Expansion in White-crowned Sparrows QUACH, LN; PEREZ, JH; KRAUSE, JS; CHMURA, HE*; WORD, KR; SCHAS, J; RAMENOFSKY, M; WINGFIELD, JC; University of Calfironia, Davis; University of Calfironia, Davis; University of Calfironia, Davis; University of Calfironia, Davis; University of Calfironia, Davis; University of Calfironia, Davis; University of Calfironia, Davis jhperez@ucdavis.edu
Global climate change has resulted in rising temperatures worldwide and an increase in the frequency and intensity of unpredictable events such as storms. These effects of global change have been particularly potent in arctic ecosystems. As a result there have been numerous range shifts, particularly northward. Previous work has shown a pattern of increased responsivity of the Hypothalamo-Pituitary-Adrenocortical axis to acute external stressors in songbird species breeding at the northern limits of their range when compared to more southerly breeding populations. Elevated stress responses may be critical for birds breeding at the northern limits of their range, allowing for rapid response to environmental perturbations at high latitudes. To date this pattern of elevated responsivity to a stressor has been detected in about ten avian species. However, these comparisons all represent large latitudinal gradients in long established populations. In this study we investigated whether this pattern holds on the smaller scale of northern pioneers on the edge of an active range expansion. We present profiles of plasma corticosterone levels in response to a standardized acute stress from free living white-crowned sparrows (Zonotrichia leucophrys gambelii ) from four locations across the latitudinal gradient of their range. Samples were taken from birds at the northern extent of their range, on the North Slope of Alaska, Toolik Lake Alaska, Fairbanks Alaska, and Washington State. Here we show that maximal stress levels are higher in Alaska than in Washington State, however, no difference was detected across a 500 mile latitudinal gradient within Alaska.
