As spring kicks in, wild turkeys begin mating play. Groups gather in lawns and fields – and sometimes in the middle of the street. The males puff out their iridescent feathers, fan their tails, and drag their wings across the ground in a fight for the right to breed. Their faces and necks take on dazzling hues of blue and red.
Once rare and elusive inhabitants of American forests, these heaviest galliform birds (chickens and their relatives) have become urban. Wild turkeys live in residential neighborhoods around my home in Madison, Wisconsin.
A few years ago, their elaborate courtship displays fascinated me so much that I started photographing them – and, as I’ve learned, there’s more going on than meets the eye.
For starters, turkeys from a feather flock together. The males, known as toms, can form lifelong herds with their brethren. Dr. Alan Krakauer, a biologist and fellow photographer, studied this as a graduate student at the University of California, Berkeley. He discovered that toms in a herd ranged from full to half-siblings. These bands of brothers cooperated in courting females, or hens, and chasing competing males.
Remarkably, however, only the dominant male mated and sired offspring. Subordinate brothers served as “wingmen”, “bodyguards” or “auxiliary dancers”, to use Dr. Krakauer’s colorful descriptions. “They have what I consider to be a supporting role,” he said.
Despite the potential for lifelong celibacy, the wingers benefited from the arrangement, Dr Krakauer found – at least by the crude evolutionary calculus. On average, dominant males with wingers produced seven cubs per season, while solitary males produced less than one. Since the males were closely related, these seven offspring contained more winger genes than if they had sired a single chick themselves.
“They help their brother get a lot more females than either of them would get on their own, so this cooperation seems particularly helpful,” Dr. Krakauer explained. “It seemed surprising to people at the time.”
Anyone who has had a sibling knows the vicissitudes of sibling relationships. While the brothers typically cooperate during mating season, intense fights break out at other times as they jostle for rank. Turkeys have formidable weapons: big bodies, powerful wings and spurred legs. On one occasion I saw a fight so violent that spit flew – like when a boxer is hit with a knockout punch.
Although males are aggressive with each other, they are not aggressive towards females and do not force copulations, despite being twice as large as their mating partners. So while the males may strut around with abandon, the females ultimately choose their mates. They are picky about partners and know what they want: men with long snoods.
Snoods are the fleshy, finger-like protuberances that collapse on a turkey’s beak. Animals can contract and relax muscles and blood vessels in the head and neck, causing changes in the length and color of the organ. A tom sporting a long red snood catches the hens’ attention like flies to honey – though, to their credit, the hens manage to be shy about it.
Dr. Richard Buchholz, a professor at the University of Mississippi, has spent his career studying wild turkeys. He examined the role that various male adornments – including snoods, wattles (pebble-like bumps on the head and neck), skullcaps (thickened skin on top of the head), spurs (talons on the legs) and beards (tufts of hair-like feathers projecting from the chest) – play in the choice of female partner. He found that the length of the snood was the main factor in explaining which male a female chose as a mate. Even a few extra millimeters made a difference.
“That surprised me, especially since the snood doesn’t seem like a very functional thing to choose,” Dr. Buchholz said. “Why the snood and not all the other adornments on men?”
The answer lies in a phenomenon deeply rooted in biology: fancy accessories can indicate good genes. For turkeys, a male who can afford to wear a killer snood must have sufficient resources, which ostensibly reflects the quality of his DNA. Dr. Buchholz found that males with longer snoods had fewer coccidia parasites, which do not harm adults but can sicken or kill chicks, and have genes that can make them resistant to coccidia.
“At first, there’s probably a big impact on chick survival,” Dr. Buchholz said, so by choosing longer males, females can provide their babies with life-saving parasite resistance.
Dr. Buchholz is still unsure what role some other male adornments play. Like snoods, other fleshy structures on a turkey’s face and neck can change color during displays. For example, the males will drain all the blood from the wattles so they are as white as a sheet of paper, Dr. Buchholz said. It remains unclear what the change in wattles might signal, or why it matters.
And what about those fancy feathers? “I don’t know if women care,” Dr. Buchholz said. The feathers of male turkeys infected with coccidia reflect less ultraviolet light, which turkeys (but not us humans) can see. However, no one has studied whether females scoff at dull feathers the way they do at puny snoods.
Much remains to be learned about wild turkey mating behavior. “For a bird that is such a great conservation achievement, that is so common and interesting to people, and that has a cultural connection to American Thanksgiving, for us, not knowing more about its behavior really a shame,” Dr. Buchholz said. .
This is perhaps not entirely surprising. Wild turkey populations are currently thriving in many parts of the country, thanks to conservation efforts; in places like New England, Madison, and Berkeley, they’re now so common that they’re about as noticed by motorists as a traffic cone.
But this has not always been the case. Until recently, wild turkeys were rare in the United States — “which seems crazy now,” Dr. Krakauer said, “since they’re in town and blocking traffic.”