"For the Truth the Turkey is in Comparison a much more respectable Bird and withal a true original Native of America..." wrote Ben Franklin in a 1784 letter to his daughter. "He is besides, though a little vain and 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."
Despite Franklin's protestations that the noble turkey replace the Bald Eagle as emblem of our great nation, we still 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. Perhaps this is all part of our own ongoing effort to create a sort of psychological distance between ourselves and the critters whose flesh we tear at with our teeth, but it turns out that the domestic turkey (Meleagris gallopavo) can actually be quite clever, at least when it comes to social cognition.
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, 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 birds of a different feather.
While they also display aggressive behavior towards each other, injuries due to pecking are much more severe and can result in death or can require that the bird be prematurely dispatched. "Assuming that individual recognition enables stable hierarchies to be established," write Swiss scientists 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. Indeed, domestic turkey flocks far outsize the flocks of their wilder ancestors, which live in groups of up to twenty individuals. But what was not known was whether turkeys can 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 - that's what you call a baby turkey - were bought from a breeder and randomly divided into four groups of eight, each with its own separate pen. For the first seven weeks, the groups were kept separate. They couldn't even see eachother. Then, 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 of four had an hour-long trial with each additional group of four, 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-on bird-on-bird fights were observed across all six trials. Fifty-six of those fights occurred between non-group members, and only five fights were observed between group members. That alone is an indication that turkeys preferentially attack strangers. 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. And 58 leaps were observed between non-group members and only 13 between members of the same group.
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. In addition, this experiment only used groups of four males. Could it be possible that, as group size increases, the ability to distinguish familiar turkeys from strangers decreases? More research could address each of those questions.
Who cares about social cognition among domestic turkeys anyway? Why does it matter, especially if they're all destined to have their cavities stuffed with aromatic vegetables and cubed bread, roasted, and served up to hungry families across America? Turkey farmers should care. 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 if a turkey becomes seriously injured, it has to be euthanized. Every turkey euthanized is a turkey that can't wind up in the meat case of your supermarket, which means financial losses for the turkey industry. It would therefore be 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.
Does this mean you shouldn't eat turkey? That's for you to decide. For me, I think there's simply value in knowing a bit more about the food I put into my mouth. 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
Image: Public domain domestic turkey flock photo via US Dept. of Agriculture/Wikimedia Commons
This post was adapted from one that originally appeared at the Scientific American Guest Blog on November 24, 2010.