Meeting Abstract
Seasonal regulation of the adrenocortical response (e.g., ‘stress response’) appears to be ubiquitous in mid- to high-latitude vertebrates. Northern Cardinals (Cardinalis cardinalis) are a temperate dwelling passerine of tropical-descent and a wide species range. This species has encountered a wide variety of environmental variation and corticosterone (CORT) has not been studied in it with an eye towards seasonal changes in levels. We analyzed cardinal samples collected between 2007-11from the Lake Thoreau Environmental Research and Educational Center (Hattiesburg, Mississippi, USA). The data suggested seasonal differences of CORT, with higher concentrations during the winter and decreasing in prebreeding, and even further during breeding where the lowest average concentrations were observed. In 2012-13 we used the same banded population of cardinals to monitor seasonal changes in stress responses. Now with more stringent initial CORT (≤3min) samples collected we observed an even more pronounced variation in seasonal CORT modulation. The data suggests significant differences of initial CORT levels between nonbreeding and that of pre- and breeding seasons. Seasonal variation was also found in the magnitude of stress responses with pre- and breeding seasons varying significantly from nonbreeding CORT concentrations. This is the first study to analyze year-round concentrations of initial CORT and magnitude of stress responses in cardinals as they progress through from one life history stage to the next.
