Meeting Abstract

P3.163  Tuesday, Jan. 6  Repeated Handling Does Not Affect Hypothalamo-Pituitary-Adrenal Development In Eastern Bluebird Nestlings (Sialia sialis) PHILLIPS, M. M.*; LYNN, S. E. ; The College of Wooster; The College of Wooster mphillips09@wooster.edu

In vertebrates, the hypothalamo-pituitary-adrenal axis is activated by a variety of unexpected events. In both wild and captive vertebrates, prior experience with a stressor has been shown to alter adults responses to subsequent stressors; however little is known about the effects of prior experience on developing animals. We studied nestling eastern bluebirds (Sialia sialis) with two goals in mind: (1) to document the time course over which HPA responsiveness to handling develops in this species; (2) to assess the effects of repeated handling on HPA responsiveness. To address goal 1, we subjected previously unhandled chicks to a capture/handling protocol when they were 6, 9, or 15 days old, and measured plasma corticosterone at 0, 15, and 30 min post-capture. To address goal 2, we handled chicks every three days, beginning with hatch, and subjected handled chicks to the capture/handling protocol when they were 6, 9, and 15 days old. Day 15 chicks showed a greater adrenocortical response than day 6 or day 9 chicks. Day 15 chicks exhibited an adult-like like response in magnitude of corticosterone secretion; however, the duration of the response was attenuated. No repeated-handling effects were found in any age group. Our results indicate that eastern bluebirds exhibit HPA responsiveness on a timeline that is similar to patterns previously demonstrated in other altricial species. However, even though prior experience with the capture-restraint paradigm is known to alter the response of adults, we did not demonstrate such an effect in nestlings. This suggests that the ability to habituate to stressors may differ by developmental stage.