Indiana University Bloomington

Birdsong and Culture

Transcript

My name is Meredith West and I'm a Chancellor's professor here at IU  in two departments, in the biology department  [background birds singing]  and in the psychological and brain sciences department.  We look at learning, in particular social learning, and even more  specifically than that we look at learning in birds and how  birds learn from one another and the behavior  that we look at in most detail is bird song.  We picked a very particular species that we wanted to study,  which is the Brown Headed Cowbird.  The female birds lay their eggs in nests of other species  so no cowbird is ever raised by another cowbird.  It's always raised by a foster species.  What few people may not realize is that birds have to learn  that particular song or melody that they're singing.  That if they don't get to hear members of their own species sing,  they don't sing a species typical song.  So a cardinal that never gets to hear another  cardinal doesn't sound like a cardinal.  And so it all depends on learning.  They have to learn how to congregate with birds of their own kind,  to listen to what the other birds are doing  and to imitate the sounds the birds are doing  and also to, what we call improvise.  The same as a Jazz musician would know  a melody but is going to take off on his own riff.  So the interesting thing from our point of view was well how does a cowbird learn  to be a cowbird if it's always around a sparrow or a cardinal or some other species?  Thirty years ago my husband and I started doing this research on asking this question  about how they learn and who they have to learn from.  And at the time people really didn't think they probably learned very much at all.  They thought it was innate, sort of just a hardwired behavior that these birds had.  But what we've learned or what we've spent thirty years doing,  is showing that it's not hardwired.  That there is a tremendous amount of flexibility and plasticity to their learning.  And DYD and DYD return, there's a female right off to his left  [background bird singing]  who is paying attention to their singing.  And BNB singing to DYD who just left and DYD following a female.  Females don't sing, so they don't respond to a male by any kind of vocalization  but they do use their wing movements.  So that a male will sing a song and a female will flick her wing out  and bring it back in very, very quickly.  What we're going to be looking at is female cowbirds,  who cannot sing, how they use visual gesture to shape males' social behavior  and what this is all about is learning how to court.  This male sings and she kind of flicks her wings back.  [background bird singing]  Now this is a really obvious wing stroke.  And so when she does give a wing strum, he gets very excited.  He kind of levitates off the perch and moves in  and tries to get in as close as he can to her  and to sing as close as possible.  And what he does then is he keeps that song that got the wing strum in his repertoire  and he may drop other songs that he sang that morning that didn't work.  And so she essentially what she's doing is she's  shaping his song by giving him reinforcement.  Culture is defined as behaviors that are passed on from one generation  to another by learning and that is what is going on in the cowbird.  But we also learned that the males could learn to change their song,  even though he had never heard it,  that even though the female had never sung it, just by the shaping process --  of taking little elements of the song and giving  reinforcement for that -- she managed to get him  [background birds singing]  to sing the kind of song she liked.