Meeting Abstract
Songbirds produce song during territorial disputes and distress calls when in mortal danger. Song sparrows (Melospiza melodia morphna) respond aggressively to conspecific song playback during both breeding and non-breeding periods. The response of song sparrows to distress call playback is not as well characterized, especially during the non-breeding period. We compared responses of 16 free-living song sparrows to both song and distress call playback on non-breeding territories under large communal crow roosts, which are potential chronic stressors, and on control non-roost territories in western Washington. Birds produced an average of 159 +/- 35 chip calls and 6 +/- 3 songs in response to a 10.5 minute distress call playback, and 36 +/- 17 chip calls and 30 +/- 6 songs in response to an 11 minute song playback. Song sparrows on territories under crow roosts did not show any differences in their responses during or immediately after distress call playback compared to non-roost birds. However, during song playback, song sparrows with territories under crow roosts spent less time within 1m of, made fewer movements towards, and did not as closely approach the playback speaker as birds on non-roost territories. To test the hypothesis that this reduced aggressive response to song is related to chronic stress associated with occupying a roost territory, we are currently measuring baseline and stress-induced plasma glucocorticoid levels.
