Meeting Abstract

P1.142  Saturday, Jan. 4 15:30  Effects of frequent disturbances on corticosterone production and infection intensity in a songbird, the dark-eyed junco HANAUER, RE*; KETTERSON, ED; Indiana University; Indiana University rhanauer@indiana.edu

When an animal colonizes a new habitat, it may encounter unfamiliar circumstances that it is not adapted or acclimated to and that are therefore likely to elicit stress responses. The steroid hormone corticosterone (CORT) increases in response to stressors, and can facilitate a return to homeostasis. However, long-term elevation of CORT poses potential costs to processes such as immunity and reproduction. Therefore, when the frequency of stressful events increases, it could be beneficial to reduce the magnitude of the CORT response. We asked whether exposure to repeated disturbances would cause a songbird to reduce its CORT response to acute stress, and whether repeated disturbances affected condition or parasite infection intensity. Adult dark-eyed juncos captured from the wild in early spring were kept in captivity for several weeks before the experiment began in May, the normal breeding season for juncos. Animals were kept on Indiana photoperiod. The control group was disturbed the minimum necessary for animal care. The experimental group was subjected to 30 minutes of disturbance four times per day for 13 days. The disturbances included close approach/loud noise, predator calls, and human voices/music. After 13 days of treatment, high-disturbance birds had less abdominal fat and trended toward having lower CORT response to handling stress than control birds. There was no difference in baseline CORT levels. Effects of the high-disturbance treatment on infection intensity of the intestinal protozoan parasite coccidia will also be reported. Results will shed light on the consequences for animals exposed to novel and persistent anthropogenic disturbances.