The Development of Local Song Preferences in Female Cowbirds (Molothrus ater): Flock Living Stimulates Learning Meredith J. West*, Andrew P. King*, David J. White , Julie Gros-Louis* & Grace Freed-Brown* * Department of Psychology, Indiana University, Bloomington, IN  Department of Psychology, University of Pennsylvania, Philadelphia, PA, USA Introduction Understanding the communicative capacities of female songbirds is critical to understanding the function of male song in mate choice and to explor- ing how vocal cultures are transmitted from one generation to the next (Searcy & Yasukawa 1996). Studies of female song preferences have increased as techniques for measuring responsiveness have been developed (King & West 1977; Nagle & Kreutzer 1997; Searcy 1992; Riebel & Slater 1998; Depraz et al. 2000; Payne et al. 2000; Nagle et al. 2002; Lauay et al. 2004). These studies focus on different levels of responsiveness, from recognition of conspe- cifics to discrimination of fine acoustic structure within songs. The results indicate that female song preference, like male song production, has a learned component in many songbird species (for reviews, Correspondence Meredith J. West, Department of Psychology, Indiana University, 1101, 10th Street, Bloomington, IN 47405, USA. E-mail: mewest@indiana.edu Received: March 2, 2005 Initial acceptance: April 27, 2005 Final acceptance: May 12, 2005 (S. Forbes) doi: 10.1111/j.1439-0310.2006.01264.x Abstract We carried out two experiments across 2 yr on song perception in female cowbirds (Molothrus ater). In the first experiment, juvenile and adult female brown-headed cowbirds, living in same-sex flocks in out- door aviaries, were periodically tutored with recordings of local male cowbirds’ songs. In the spring, four adult male cowbirds were placed with half of the females for a 12-d period. We then tested song prefer- ences of all females by measuring copulation solicitation displays during the breeding season. We found that the females exposed only to tape- tutor songs preferred those songs to those of the unfamiliar males used as companions and that the females allowed to interact with males pre- ferred their songs over the familiar tape-tutor songs. These data establish the modifiability of female cowbirds’ song preferences at the level of local song. In a second experiment, we studied the playback responses of juvenile females, hand-reared from the egg, who were tape-tutored only in the spring in the presence or absence of adult females. There were no differences between the responses of juveniles housed with or without adult females and the hand-reared juveniles were significantly less responsive to song than adult females. Adult females responded more to familiar songs than to the unfamiliar songs: juvenile females made no such distinction. Taken as a whole, these data are the first to document that female cowbirds’ song preferences for local song can be reshaped by post-natal experience. These data complement recent study in cowbirds and other species showing that socially more complex con- texts reveal plasticity in female song preferences that are not apparent when learning opportunities are constrained by impoverished laboratory settings. Ethology Ethology 112 (2006) 1095–1107 ª 2006 Blackwell Verlag, Berlin 1095