As anyone who has ever tried to eat french fries on a beach will confirm, stealing is not uncommon behavior in birds. Indeed, many birds are quite adept at daring and audacious theft.
Scientists have documented several species of birds, including magpies, bowerbirds, and black kites, which loot everything from discarded plastic to expensive jewelry to decorate their nests. And then there are birds that want hair and try very hard to get their beak on it.
Hair from dogs, raccoons, and even humans has been found in bird nests, which scientists believe may better insulate the nests. For a long time, scientists assumed that birds had to collect lost hair or clean it from the carcasses of mammals. However, a new study published last week in the journal Ecology shows that several species of birds, including titmice and titmouse, not only eat up hair, they steal it.
The study, which is largely based on analysis of YouTube videos, reveals numerous examples of birds pulling tufts of hair from living mammals, including humans. This phenomenon, which the study’s authors called Kleptotrichy, has been well documented by online bird watchers, but this is the first time scientists have officially recognized it.
“This is just another example of something that was overlooked in the scientific literature but was well known in the bird watching and bird-feeding community,” said Henry Pollock, postdoctoral fellow in ornithology at the University of Illinois and co-author of New Learn.
Last spring, Dr. Pollock was attending his university’s annual spring bird census when a tufted tit caught his eye. It scurried near a raccoon that was fast asleep on a branch and came closer and closer to it. Then the little bird began to look at Dr. Pollock’s amusement at plucking tufts from the raccoon’s fur. The tit managed to steal over 20 beak fulls of the raccoon’s fur without waking it.
After Dr. Pollock witnessed this delightful theft, he began scouring the scientific literature to see if anything like it had ever been documented.
He found only 11 recorded cases of birds stealing hair from living mammals, including reports of honey-eaters plucking koala’s hair and a 1946 observation of a tit plucking hair from a red squirrel’s tail. Dr. Pollock looking for examples of this behavior outside the scientific literature. This turned out to be much more fruitful. A simple search on YouTube found nearly a hundred videos of birds roaming around with mammalian fur. Ninety-three percent of the videos that Dr. Pollock found showed tufted tits that pluck hair from domestic dogs and humans (in this case, without much success).
The remaining seven percent of the videos showed parids, the bird family that includes titmice, titmouse, and titmouse who sneak up on and steal hair from raccoons, cats, dogs and, in one video, a North American porcupine. Dr. Pollock realized that this behavior was not only widespread, especially among parids, but was also known to bird enthusiasts.
“I saw it in person,” said Daniel Baldassarre, an assistant professor at SUNY Oswego who studies the behavioral ecology of city birds. “I used to live somewhere where I had birdhouses on my porch railing and my yellow lab was on the deck and tits landed on it and tore its fur off,” said Dr. Baldassarre, who was not involved in the project, learn. “This is the cutest thing you’ve ever seen.”
Dr. Baldassarre is not surprised that kleptotrichy appears to be widespread in paridae because the birds in this family are “the kind of species that would find out this behavior. You are very brave, inquiring and clever. “
Both Dr. Baldassarre and Dr. Pollock suspect that the birds who commit these acts of theft in order to isolate their nests. Tufted tits and other parids “nest in early spring when the weather is still pretty cold, so it is definitely important to keep the nest warm,” said Dr. Baldassarre. A review of the scientific literature on the nests of 51 species of paridae found in 44 mammalian hairs. The seven species with fur-free nests all live in areas with warmer climates.
Dr. Pollock hopes further research will help scientists determine the costs and benefits of kleptotry and how widespread it is in birds. He also hopes this study will demonstrate the value of community knowledge and other non-traditional sources of information.
“As a scientist, you have to be open to exploring alternative sources of information. I think the usefulness of popular literature is often underestimated, and the bird watching community in particular is often underestimated. “