Early-life stress affects the behavioural and neural response of female song sparrows to conspecific song

Abstract

In songbirds, both song production and song preferences may be influenced by early-life experience. Early-life stress impairs development of the song-control brain regions and permanently affects male song production. However, few studies have examined the effects of early-life stress on female song preferences or the brains of female songbirds. We exposed female song sparrows, Melospiza melodia, to stressors (food restriction or exogenous corticosterone treatment) early in development. When birds were adults, we determined the effects of the stressors on: (1) the behavioural response to high-complexity versus low complexity-songs as well as to conspecific versus heterospecific songs; (2) the volume of song-control brain regions; and (3) the immediate early gene (Zenk) response in auditory forebrain regions following exposure to either conspecific or heterospecific song. We found no significant effect of developmental stress on the strength of the behavioural response to high- versus low-complexity song, but control females showed more selectivity in their behavioural response to conspecific versus heterospecific song when compared with food-restricted or corticosterone-treated birds. We observed no effect of either stressor on volume of the song-control nuclei. Control females exposed to conspecific song had more Zenk-immunoreactive cells in the auditory brain regions than control females exposed to heterospecific song. In contrast, food-restricted and corticosterone-treated females did not have more Zenk-immunoreactive cells after exposure to conspecific song. These results show that stressors known to affect male song production might also affect neural processing of song by females, and their subsequent behavioural response to song.