Some birds steal hair from living mammals, study finds

Date:
July 30, 2021
Source:
University of Illinois at Urbana-Champaign
Summary:
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.



FULL STORY ========================================================================== Dozens of online videos document 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.


==========================================================================
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 found only a few descriptions of the behavior in the scientific literature but came up with dozens more examples in online
videos posted by birders and other bird enthusiasts. In almost all the videorecorded cases, the thief is a titmouse plucking hair from a cat,
dog, human, raccoon or, in one case, porcupine.

Many species of titmice, chickadees and tits -- all members of the family Paridae -- are known to use hair or fur to line their nests, said Mark
Hauber, a professor of evolution, ecology and behavior at the University
of Illinois Urbana-Champaign who led the write-up with postdoctoral
researcher Henry Pollock. The hair's role in the nest is still debated, although it is more commonly used by birds nesting in temperate climates,
so maintaining warmth in the nest is thought to be one advantage.

The impetus for the study came from a chance sighting. Study co-author
U. of I.

natural resources and environmental sciences professor Jeffrey Brawn
first observed the behavior with Pollock while on a spring bird count
in central Illinois.

Scientists once 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, Brawn said.

"But the titmouse I saw was plucking hair from a live animal," he
said. "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." A search
of published research turned up just nine studies that documented 11
instances of the behavior, but a YouTube search yielded many more cases,
Hauber said. Sometimes the target animals were sleeping, and sometimes
they were awake.



==========================================================================
"We know, of course, that birds use a variety of materials to line their nests," Hauber said. "But why are these birds risking their lives to
approach these mammals?" The behavior suggests that the benefit of
lining its nest with hair outweighs the danger to the bird, he said.

It may be that the birds simply need the hair to insulate their nests,
but the presence of mammal hair -- and the associated odor of the
mammal -- could also deter nest predators like snakes or other birds,
the researchers said.

"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," Hauber said.

The hair also may repel nest and nestling parasites, which are a common
threat to chick survival, especially in cavity nests like those of
titmice, he said.

Regardless of the purpose of the behavior, the new paper is the first to document so many examples of hair-plucking by birds in a single report. In addition to citing nine papers about the phenomenon, it also links to
dozens of online videos. Collectively, the videos show titmice -- and
in one case, a black-capped chickadee -- plucking hair from 47 humans,
45 dogs, three cats, three raccoons and a porcupine.

"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.

========================================================================== Story Source: Materials provided by
University_of_Illinois_at_Urbana-Champaign. Original written by Diana
Yates. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Henry S. Pollock, Sean E. MacDonald, Jeferson Vizentin‐Bugoni,
Jeffrey D. Brawn, Zachary S. Sutton, Mark E. Hauber. What the pluck?
Theft of mammal hair by birds is an overlooked but common behavior
with fitness implications. Ecology, 2021; DOI: 10.1002/ecy.3501 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/07/210730104316.htm

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