A bird's eye view of social networks
Introvert or extrovert? The two terms hover over the research of Gregory Kohn (Ph.D. ’15) like the birds that inhabit the aviaries of the Animal Behavior Farm, aka the lab of PBS professor Meredith West and senior scientist Andrew King. Kohn has worked and studied in this lab, first as a Ph.D. student, then as a post-doctoral researcher.
The question, suggests Kohn—introvert or extrovert?—is as pertinent to non-human animals as it is to humans. The sociability of each individual animal adds up to a collective pattern of social organization, a social network differentiated by gender in which males and females generally play different roles.
In social mammals from elephants to apes, baboons and horses, Kohn explains, studies of sociability have brought to light overall differences between female and male group members in which females consistently interact with familiar, mostly female, individuals, while males are flexible and more varied in their interactions. Together the two tendencies provide a balance between stability and change within the networks, making it easier and more likely for the social organization to thrive and perpetuate itself.
Now Kohn’s research shows for the first time that this social dynamic extends to birds. In a study of brown-headed cowbirds, Kohn has demonstrated that the social bonds between particular female cowbirds are sustained across changes in group size and membership. Males by contrast fluctuate in their associations, forming new associations in a way that integrates new members.
Counting how often an individual seeks out social contact and with whom, whether with the same or varying individuals, Kohn has measured degrees of sociability in the society of brown-headed cowbirds. And these differences add up into telling patterns.
An ordinary, even somewhat drab looking brown and black bird, cowbirds at the Animal Behavior Farm have been the unwitting proponents for a line of reasoning that puts social networks into the foreground of theories about learning and development, not only in cowbirds, but in numerous social species. The unique conditions at the Farm/Lab, have allowed for this. As the largest aviary in Indiana, with a complex of four interconnected aviaries the size of a football field, the Animal Behavior Farm is specially equipped, unlike almost any other lab in the country, to both recreate conditions in the wild and maintain a certain amount of control.
In the wild, for example, it is extremely difficult to track the consistency of social interactions among cowbirds. Yet, here they have a system for labeling and observing the same cowbirds over time and bringing together or varying group populations.
Laying their eggs in the nests of other species, cowbirds, Kohn explains, which are raised by other species, would seemingly be the perfect candidate for a genetically programmed view of development. How else would they find their way back to their kind and reproduce?
Yet, Kohn contends, “The opposite is true.” Decades of studies at the Animal Behavior Farm suggest that “external stimulation from the social environment teaches them how to be cowbirds.”
Cowbirds initially find their way back to the company of cowbirds in their search for the same food on edge habitats. There they interact with other cowbirds, who unlike other birds, will respond in kind to their characteristic head-down display. Getting this favorable response from other cowbirds, says Kohn, “may make them more likely to hang out with each other” and draws them into cowbird society.