Meeting Abstract

38.4  Tuesday, Jan. 5  Corticosterone, corticosteroid-binding globulin, and free corticosterone, 24-72 hours following an acute stressor in a wild population of white-crowned sparrows MALISCH, J.L.*; CRINO, O.L; BREUNER, C.W.; University of Montana jessica.malisch@mso.umt.edu

The acute stress response is typically assumed to be a short-term (minutes to hours) rise in circulating glucocorticoid levels. However, acute stress in laboratory populations of mice and Japanese quail has been shown to alter hormone profiles 24 hours after the termination of the stressor. These changes include increased baseline corticosterone (CORT: the primary glucocorticoid in birds and mice), increased free CORT and decreased corticosteroid-binding globulin (CBG) levels. These more long-term changes in hormone levels indicate that the repercussions of an acute stress response may last for days as opposed to minutes or hours. Here we investigate this phenomenon in a population of free-living white-crown sparrows (WCSP) from Tioga Pass, CA. WCSP were captured in seed-baited Potter traps between 8:00-13:00 hours in May and June of 2009. Baseline blood samples were obtained within three minutes of the observer approaching the trap; each bird was held in a cloth bag for 15 minutes and released. Birds were recaptured 24, 48 or 72 hours later and a second blood sample was obtained at this time. We predicted that baseline total CORT and baseline free CORT would be elevated and CBG levels would be reduced for at least 24 hours following acute stress, as has been found for laboratory animals. In mice CORT and CBG return to pre-stress levels within 72 hours. Therefore, we predicted total CORT, free CORT, and CBG at 72 hours to not differ from the initial blood sample. Interestingly, we saw no change in total CORT 24, 48, and 72 hours following the initial blood sample. Analysis of CBG and calculation of free CORT are still under investigation.