In a paper published in Nature in 1988, Meredith West and Andrew King demonstrated that that a wing stroke visual display by female cowbirds, which don’t sing, plays a role in song learning of male cowbirds. The findings of the study provided evidence for the role of visual stimulation in song development, a process that till then was thought to be shaped only by vocal stimulation. Twenty-eight years after the paper was published, I asked Meredith West about how she got interested in this topic, her memories of these experiments, and what we have learnt since about this topic.
Citation: West, M. J., & King, A. P. (1988). Female visual displays affect the development of male song in the cowbird. Nature, 334(6179), 244-246.
Date of interview: 15th October 2016 (via Skype)
Hari Sridhar: At the time when you wrote this paper, you had already spent more than 10 years studying cowbird vocalization. What was your motivation to do this particular piece of work?
Meredith West: Well, we were studying dialects in cowbirds, which means the birds in North Carolina sing a different song than the birds in Texas. Those were the two populations we worked with, and we did a number of studies that showed that if males were raised … if North Carolina males were raised with Texas females, their song didn’t develop normally. And we wondered why, because most of the theories of vocal development stress imitation – vocal imitation. And females don’t sing, so how could the females be communicating something about their dialect to the males? And we’d done several studies on this phenomenon. This was published in Nature in 1983. So we decided to videotape birds in the winter and the spring. And to look at males and females who were raised together, and to see what kind of behavior we saw between the two of them. And in doing that, we discovered the wing stroke, but looking at videotapes, we couldn’t see it live. We could only see it when we slowed down the videotape. So, that got us started. We recorded number of birds, males versus females, and photographed them and got down our definition for the wing stroke and other behaviors. And that’s what got us started with it.
HS: Do you remember when you first saw this wing stroke on a video?
MW: It was in March 1987.
HS: Stepping back a bit, could you tell me how you got interested in studying cowbird vocalizations?
MW: Well, we were interested in birdsong in general, and we were interested in cowbirds because they don’t raise their own young. They are raised by other species, and we wondered how a species that didn’t have parental behavior learned song. And so we started working with birds that we had hand-raised and looked at their song development and found it was quite abnormal if they weren’t raised with males and females. So, if we just raised them with females their song would be abnormal, and if we just raised them with males their song was somewhat better but it still wasn’t normal. And that’s what got us interested in cowbirds, was how they learned their song, and how they used it with females in particular, because we discovered, very soon after we started working on this, that females have a good response to song – a copulatory posture that they gave when they heard the song. So we had a good bioassay of song function. And we used that to study males that have been raised in different ways. We played those songs back to females and got an idea about which songs were considered good or songs that were considered bad. That started right at the beginning of our work.
HS: This paper was written by you and Andrew King. I notice that you have written a number of papers with him. Can you tell us how this collaboration started?
MW: Well, we were graduate students together at Cornell. And we were friends and we ended up getting married. And so we just worked together collaboratively from the time we were at Cornell onwards. We did different dissertations, but we were beginning to do the cowbird work and ended together.
HS: Typically, in the work you do together, do each of you have specific roles, in terms of what you bring to the studies?
MW: It really depends on the study. In general, Drew does most of the video recording and the audio recording, and I help with the analysis, and we both look over the data and both contribute to writing the paper.
HS: For this study, you say you captured wild-caught male juveniles under the age of 50 days and adult females. Can you tell us when and where you captured these birds?
MW: I guess it would have been in 1987.
HS: Where did you capture these birds?
MW: In and around Ithaca, New York. And we got eggs from an aviary of females and males, and we incubated the eggs, or we had canaries incubate the eggs. And then we raised the young birds from hatching, which was a lot of work. But that was the only way to get juveniles that had the kind of experience that we wanted.
HS: Was the aviary in Cornell?
MW: It started at Cornell, yes. So the experiments that went into this paper were done at Cornell. No, they were done in North Carolina. We started at Cornell but the actual study you’re talking about was done at the University of North Carolina.
HS: Do you usually name the birds that you use in your experiments?
MW: No, we don’t. We have bands on their legs that are different colors. And so the birds are known as ‘two-red’ or ‘dark blue-green’ or whatever their bands say. We don’t have particular nicknames for them or anything.
HS: After this experiment, how long did you continue to use these birds and the experimental setup?
MW: Well, we did different kind of experiments, but we used that set up for the next five years or so. We looked more closely at what other behaviors the females might be using, but the wing stroke turned out to be the big behavior. And we looked at different subspecies of cowbirds and saw the wing stroke in different subspecies. And we did that using the same set up that we’d done for the Nature paper.
HS: Did you do this work when you were a professor at North Carolina?
MW: That’s right. And my husband was at Duke University.
HS: Did you stop using this experimental setup because you moved out of North Carolina?
MW: That’s right, we moved to Indiana and we set up a laboratory that had more outdoor spaces for animals more aviaries that are very large. One is the length of a football field. And we stopped doing the work we had done like in the Nature paper where we put the birds in sound attenuating chambers and studied them under those conditions. We began studying birds living in flocks, because we knew, in nature, that’s how they learned. They lived in flocks. They didn’t live, you know, one male and one female together. That’s why we wanted to get more natural behavior.
HS: Once you moved out of North Carolina, what happened to the experimental setup?
MW: We brought it with us to Indiana. We just moved to the lab and brought the equipment with us. And we set up the sound attenuating chambers here, but used them for playback experiments where we playback songs to females during the breeding season. But we didn’t use them for developmental studies.
HS: What about the birds?
MW: Well, we captured birds here in a trap. And we also got birds from South Dakota, which are a different subspecies, and began studying two different subspecies.
HS: What about the birds that you were using in North Carolina?
MW: We brought with us.
HS: What was your daily routine when you were doing this study?
MW: Well, birds were living in sound attenuating chambers. We would ordinarily use a male and two females in each chamber. And we recorded them in the morning. starting about 9 o’clock to about 11 o’clock. And then afterwards, we fed them and gave them new water and things like that, but we didn’t do much with them in the afternoons. So the experiment really took place in the morning hours and took place for the whole spring.
HS: Did you have people to help you with the experiments?
MW: No, we had no help.
HS: Do you remember approximately how long it took for you to write the paper and when and where you did most of the writing?
MW: Well, it was done in Indiana..no, it was done in North Carolina. And I don’t remember how long it took; maybe three months.
HS: Were you and Andrew King involved in the writing of the paper?
MW: Yes.
HS: Do you still have the videotapes and recordings you made during this study?
MW: Yes, we do.
HS: Do you go back and look at these videos even now for any reason?
MW: No we don’t, not very often. They’re on VHS tape which isn’t used anymore. We use different kind of recorders – DAT recorders – now. So we don’t have the right kind of playback machine. But if we had to, we could find a way to look at them.
HS: Do you remember how you drew the figure – the bar graph – in this paper?
MW: I think we had that done professionally. North Carolina had an art studio for people who were doing science. And I think we brought them a hand version of that graphic and they made it look nicer.
HS: You received financial assistance from the National Institute of Neurological and Communicative Disorders and Stroke. Why was this institute interested in your work?
MW: Well, they were interested in vocal development, and they were interested in what kind of stimulation was necessary for vocal development to occur naturally. And this work fit into that kind of framework. So they gave me a career development award to study this for five years. We also were funded by NSF.
HS: Did this paper have a relatively smooth ride through peer review? Was Nature the first place you submitted it to?
MW: Yeah. Oh, very smooth. I don’t remember exactly how long it took, but it didn’t take very long at all.
HS: And at the time it was published, did it attract a lot of attention?
MW: We got a lot of publicity. Yeah. There was an article in The New York Times, a lot of newspapers picked it up and science magazines. So it got quite a bit of publicity.
HS: What about within academia itself? Were the results considered controversial at the time?
MW: Yes, because the ongoing theory was that birdsong was learned by imitation. What we were showing was that non-vocal stimulation was contributing to vocal learning. So it didn’t fit with the major paradigm of the day. And so it took a couple of years for people to accept it. They accepted it, but they incorporated it into their theories, only when Peter Marler, who was sort of head of birdsong in this country, called it action-based learning and incorporated it into his theories as action-based learning
HS: This paper has been cited a lot. Do you have a sense of what it mostly gets cited for?
MW: No, I don’t. I think it’s because it’s the female and the male doing something together, that got people interested in it. But I don’t really know why it’s widely-cited; but it is. It was the first time people had shown that non-vocal stimulation affected birdsong learning. So it was important in that sense. And the wing stroke was just an interesting behavior which you couldn’t see it live, you had to see it slowed down on videotape, but once you saw it, you never forget it. And it explained how the females were affecting the males. And that was of interest to people who looked mainly at males and how males learn and so on. And so looking at females was something new.
HS: Did this paper have any kind of direct impact on your career, and did it have an influence on the future course of your research?
MW: It got us more interested in females. We did a number of studies of females and flocks and looked at how they learned their song. And it appeared that they learned it by looking at the wing strokes of other females. So we did continue with the wing stroke in enlarged aviaries and we played back song and looked at the females who produce wing strokes and what the other females did around them. And in subsequent studies that we did, we’ve shown that females could modify their preference for song based on flock stimulation, and that contradicted a finding we had had years ago that suggested that females didn’t learn their song preference; that it was innate. But this showed that that was just in that setting of the sound attenuating chamber, that that didn’t stimulate learning, but the flock setting did.
HS: Did this paper have any direct influence on your career?
MW: Well, it probably helped us get the job in Indiana. And helped us get the next grant.
HS: Today, 28 years after this paper was published, would you say that the main conclusions of this paper still hold true more-or-less?
MW: Yes.
HS: If you were to redo this study today, would you do anything differently, given the advances in technology, theory and statistical techniques?
MW: Well, we would use better video. I think that would be the biggest change that we’d make. We’d try to also study males that live with males and females to see what happened when they had influence of both males and females. So, we would add another condition.
HS: You said that, after this study, you moved to studying different topics. So, I’m guessing you haven’t followed-up in these ways on the same questions?
MW: Well, we do some video-taping in the aviaries, and use better equipment, but we don’t do the kind of microscopic developmental work that we did then.
HS: Towards the end of your paper, you say, “the present study underscores the multimodal nature of the stimulation available to males as they learn to sing, and adds credence to a multi-phasic view of song learning whereby it is influenced by both natal and juvenile experiences”. Since this study, has there been more attention to the possibility of visual dimensions of song learning and the multi-phasic nature of song learning? Have more examples being discovered?
HS: Yes. There’s wing stroking in zebra finches, for example. People have discovered that, and most people accept that, song is a multi-phasic developmental phenomenon now. Not too many people studying non-vocal stimulation. But people have done other studies trying to use the wing stroke as a reinforcer for behavior. Michael Goldstein did some of that work and Carol ten Cate did work on wing stroke in, I’m not sure, I think it was the zebra finches. So there’s been acceptance of it. There have also been attempts to look for it in other species.
HS: Do you think that there are likely to be many more species where it is important?
MW: I really don’t know. I think female stimulation is more important than people give it credit for, in terms of song learning, and people still focus mainly on males. And until they start studying females they’re not gonna find things like the wing stroke. So they have to change their design. And most of the work now in birdsong is done on the brain. That doesn’t fit with the kind of work that we did. We don’t do brain studies.
HS: Since the time this paper was published, have you ever read it again?
MW: I read it again a couple of years ago, just to remember what it was like and to remember how we did it. And when you emailed me, I looked at the paper.
HS: If you compare this paper to the papers you write today, do you notice any striking difference?
MW: Not really.
HS: Would you count this paper as a favorite among all the papers you’ve written?
MW: Yes, it’s not the favorite, but it is one of the top five.
HS: Could you tell us a little more about what you like about it?
MW: Well, I like that it looked at the social dimension of local development, and then looked very carefully at the behavior of the male and the female. I mean, part of what we saw when we first saw the wing stroke was the male kind of jumping off the perch when he saw the wing stroke and that was very interesting. I forget what you asked me now.
HS: Why do you like this paper?
MW: I think that’s why I like it. It showed both sexes working on vocal epigenesis. And we were just sort of intrigued to find this very brief behavior that has such an impact on song development. I mean the wing stroke is only about a second long
HS: What would you say to a student who’s about to read this paper today? What should he or she take away from this paper? And would you add any caveats?
MW: I think the only caveat I would add is that the circumstances under which we did our tests on females in sound attenuating chambers with males is very unnatural. And that it would be better to try to show it in the flock setting where there are more males and females present. We stopped doing work inside attenuating chambers because it just seemed like not a very good environment for the birds. I mean, the chambers are very large and they had a lot of room to fly and things like that, but it still isn’t the same as an outdoor facility, where the birds can decide who they want to be with and form groups of their own volition. We were forcing males and females together, and I think I would rather have them try to connect naturally. So that’s what I would say.
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