November 24, 2010 | 6
It is well-known that when the bald eagle was picked for the emblem of America after six years of debate, Ben Franklin expressed his dismay that the turkey was not picked instead. In a letter to his daughter, he wrote,
For the Truth the Turkey is in Comparison a much more respectable Bird, and withal a true original Native of America . . . He is besides, though a little vain & silly, a Bird of Courage, and would not hesitate to attack a Grenadier of the British Guards who should presume to invade his Farm Yard with a red coat on.
Even still, we tend to think of the turkey as a fairly unintelligent bird, skilled at little more than waddling around, emitting the occasional "gobble," and frying up golden-brown-and-delicious. But…what if I told you that the domestic turkey (Meleagris gallopavo) could actually be quite clever, at least when it comes to social cognition? Apocryphal or not, Ben Franklin may have been on to something with the "Bird of Courage."
Wild turkeys, like many birds, are social creatures. About six months after hatching, the males from the same brood break away and form a sibling group that generally persists for life. Like any other group of siblings, they’re fiercely loyal to each other and extremely hostile to outsiders. And, like most groups of social animals, there is a very strict dominance hierarchy both within and between groups. If an outsider turkey wanders into the wrong side of the forest, the ensuing fight won’t be pretty. Feathers would fly and beaks would peck. Whatever injuries might be sustained in such a turkey altercation, though, aren’t usually particularly dangerous or life-threatening. But domestic turkeys are a different story. While they also display aggressive behavior towards each other, injuries due to pecking are much more severe and can result in death or can necessitate early euthanization of the bird.
"Assuming that individual recognition enables stable hierarchies to be established," write Swiss scientists Drs. Buchwalder and Huber-Eicher, "it has been suggested that large flocks continually attempt to establish dominance, leading to high levels of aggression." The problem is that domestic turkeys live in such large flocks that the neural computation and memory requirements to identify each member of the flock and to distinguish flock members from outsiders may be too great, resulting in failure. It is indeed the case that domestic turkeys live in much larger flocks than their wild ancestors (which have groups containing up to twenty individuals), but it was not known whether they are able to distinguish in-group members from out-group members. Buchwalder and Huber-Eicher reasoned that if domestic turkeys directed their aggression preferentially towards members of a different flock or social group, they might indeed be able to distinguish among individuals.
Thirty-two six-week-old turkey poults were bought from a breeder and randomly divided into four groups of eight, each with its own pen. The pens were arranged such that the different groups were unable to see each other. Seven weeks later, when the turkeys were 13 weeks old, four males randomly selected from each of two different groups were placed in a slightly larger experimental pen for one hour. This meant that each trial included eight male turkeys: four from one group, and four from a second group. Each group had an hour-long trial with each additional group, resulting in three trials per group and a total of six trials, which were conducted across three days. The entire pen was videotaped and the researchers collected data on the number and duration of aggressive interactions (fights, aggressive pecks and running leaps) between each individual.
A total of 61 full-fledged fights was observed across all six trials. Fifty-six of those fights occured between non-group members, and only five fights were observed between group members. In addition, 157 aggressive pecks (which did not escalate into fights) were observed between non-group members, while only 15 pecks were observed between members of the same group. Likewise, there were 58 leaps observed between non-group members and only 13 leaps between members of the same group. Each of these differences was statistically significant.
Although it is clear that domestic turkeys, by the age of 13 weeks, are able to distinguish in-group members from out-group members, it is not clear if they recognize others on an individual basis or if there is some other characteristic shared by group members that provides information about group membership more generally. Additional research is necessary to tease apart these possibilities. In addition, this experiment only used groups of four males. It is possible that as group size increases, the ability to detect strangers decreases, and further research could elucidate this question as well.
Who cares about social cognition among domestic turkeys? Well, turkey farmers should. Not only do fights among turkeys have the potential to seriously reduce their quality of life during the short time they’re alive (16 weeks, in case you were curious), but they can also result in financial losses for the turkey industry. It would be, therefore, in the best interests of turkey farmers to ensure the relative happiness of their turkeys by keeping groups isolated from each other, at least until they become plump enough to be slaughtered for serving on Thanksgiving tables across the country.
So, tomorrow night, while carving up your golden-brown turkey, take a moment to appreciate the complex social-cognitive abilities of these delicious birds. Domestic turkeys do more than just pair well with mashed potatoes and cranberry sauce: they can distinguish group members from strangers. And that’s nothing to gobble at: human infants can’t reliably distinguish among unfamiliar human faces until 19 weeks of age!
Buchwalder, T. (2003). A brief report on aggressive interactions within and between groups of domestic turkeys (Meleagris gallopavo) Applied Animal Behaviour Science 84 (1), 75-80 doi: 10.1016/S0168-1591(03)00149-7
ABOUT THE AUTHOR Jason G. Goldman is in his fourth year as a doctoral student in developmental psychology at the University of Southern California. His research focuses on the evolution and architecture of the mind and how different early experiences might affect innate knowledge systems. To investigate these issues, he conducts studies in three populations: human adults, nonhuman adult animals, and nonhuman infant animals. Studies of each population allow unique questions to be asked about the evolution and development of cognition. He is also psychology and neuroscience editor at ResearchBlogging.org and is the editor of the 2010 edition of Open Lab, the yearly anthology of the best science writing on the web. He writes the Thoughtful Animal blog and can be found on twitter: @jgold85.
The views expressed are those of the author and are not necessarily those of Scientific American.