A new study reveals an unusual behavior among tufted titmice and their bird relatives. A bird will land on an unwary mammal and carefully and stealthily pluck out some of its hair. Dozens of online videos show unusual behavior among tufted titmice and their bird relatives. A bird will land on an unwary mammal and carefully and stealthily pluck out some of its hair.
A new paper in the journal Ecology documents this phenomenon, which the authors call “kleptotrichy,” from the Greek roots for “theft” and “hair.” The authors discovered dozens of more examples of the behavior in online videos posted by birders and other bird enthusiasts, despite finding only a few descriptions of the behavior in the scientific literature. The thief in almost all of the videotaped cases is a titmouse plucking hair from a cat, dog, human, raccoon, or, in one case, porcupine.
A new paper documents an unusual behavior among tufted titmice and their closest bird kin. A bird will land on an unsuspecting mammal and, cautiously and stealthily, pluck out some of its hair.
Many species of titmice, chickadees, and tits – all members of the family Paridae – are known to line their nests with hair or fur, according to Mark Hauber, a professor of evolution, ecology, and behavior at the University of Illinois Urbana-Champaign who led the study with postdoctoral researcher Henry Pollock. The role of hair in the nest is still being debated, though it is more commonly used by birds nesting in temperate climates, so keeping the nest warm is thought to be one advantage.
A chance sighting sparked the idea for the study. U., one of the study’s co-authors, I am. Professor of natural resources and environmental sciences Jeffrey Brawn first noticed the behavior in Pollock while on a spring bird count in central Illinois.
According to Brawn, scientists previously assumed that birds with hair in their nests had collected it from the carcasses of dead mammals or found hair that had been shed into the environment. “However, the titmouse I saw was plucking hair from a live animal,” he pointed out. “This was from a live raccoon, complete with claws and teeth, and the raccoon didn’t seem to mind because it didn’t even wake up.”
A search of published research yielded only nine studies that documented 11 instances of the behavior, but Hauber said a YouTube search yielded many more cases. The target animals were asleep at times and awake at others.
“Of course, we know that birds line their nests with a variety of materials,” Hauber explained. “But why are these birds risking their lives to approach these mammals?” he asks, implying that the benefit of lining the bird’s nest with hair outweighs the risk to the bird.
The birds may simply require the hair to insulate their nests, but the presence of mammal hair – and the associated odor of the mammal – could also deter nest predators such as snakes or other birds, according to the researchers. “There’s a local species called the great crested flycatcher, which is a cavity nester like the titmouse and actually puts shed snakeskins into its nest, possibly to deter predators,” Brawn said.
“In Africa, there are finches that put mammalian fecal material on top of their enclosed nests, presumably to confuse and thus keep predators away,” Hauber explained. According to him, the hair may also repel nest and nestling parasites, which are a common threat to chick survival, particularly in cavity nests like those of titmice.
Regardless of the reason for the behavior, the new paper is the first to document so many instances of bird hair-plucking in a single report. It not only cites nine papers on the phenomenon, but it also links to dozens of online videos. The videos show titmice – and, in one case, a black-capped chickadee – plucking hair from 47 people, 45 dogs, three cats, three raccoons, and a porcupine.
“Unexpected interactions like these remind us that animals exhibit a wide range of interesting and often overlooked behaviors, and they emphasize the importance of careful natural history observations in shedding light on the complexities of ecological communities,” Pollock said.