Sneaky birds are risking their lives to line their nests with something unusual —animal fur, or sometimes, even human hair.
But it’s not all fun and games for these shameless creatures. Mammal hair may provide the right type of insulation for birds’ nests, especially since the odor associated with it can help keep predators away, a new peer-reviewed study finds.
Mammal fur may also prevent pesky parasites from getting in the nest, which is one of the biggest threats to chick survival, scientists add.
Scientists originally thought birds had collected fur from the carcasses of dead animals or stumbled upon the hair in the environment, the study suggests.
But they soon discovered that was not the case.
“The titmouse I saw was plucking hair from a live animal,” co-study author and postdoctoral researcher Jeffrey Brawn told the Illinois News Bureau at the University of Illinois. “This was from a live raccoon with claws and teeth. And the raccoon didn’t seem to mind because it didn’t even wake up.”
Brawn first observed this phenomenon with fellow researcher Henry Pollock, a postdoctoral researcher at the University of Illinois at Urbana-Champaign.
The two were in a public park when they saw a “small gray-and-blue bird with a pointed black head crest,” Live Science reports. The bird was a frequent visitor to the park, but what it was doing was revelatory.
It stood on the raccoon’s back and just kept picking off hair from the animal. “At that moment, my curiosity was piqued,” Pollock told the news outlet.
Pollock searched scientific journals in hopes of understanding this unusual behavior. He stumbled on one paper published by researcher A. C. Bent, who saw a titmouse plucking fur from a red squirrel’s tail — but didn’t consider it to be more “widespread behavior,” the science news outlet adds.
Pollock and Brawn say they eventually found nine studies detailing 11 examples of this trend, but the real “aha moment” came from videos posted to YouTube by bird enthusiasts, the study says. Nearly all recorded case showed a titmouse — with one exception being a black-capped chickadee — “plucking hair from 47 humans, 45 dogs, three cats, three raccoons and a porcupine.”
It was only fitting that the researchers name this phenomenon “kleptotrichy,” deriving from Greek words for “theft” and “hair.”
The titmouse is not the only bird species with a keen interest for the unusual plucking.
“There’s a local species called the great crested flycatcher, which, like the titmouse, is a cavity nester, that actually puts shed snakeskins into its nest, possibly to deter predators,” Brawn said.
“There are finches in Africa that put mammalian fecal material on top of their enclosed nests, presumably to confuse and thus keep predators away,” Mark Hauber, a professor of evolution, ecology and behavior at the University of Illinois Urbana-Champaign, said in a press release.
The researchers’ findings were published in the paper ”What the pluck? Theft of mammal hair by birds is an overlooked but common behavior with fitness implications.” It’s the first study to document numerous examples of fur bird thieves in a single report.
“Unexpected interactions such as these remind us that animals exhibit all types of interesting and often overlooked behaviors and highlight the importance of careful natural history observations to shed light on the intricacies of ecological communities,” Pollock said.
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