Bird-watchers in Paris have for years noticed something odd about the city's pigeons: Many of the omnipresent avians are missing one or more toes.
Now, scientists think they know why, and it's a bit of a head-scratcher: A new study suggests that human hair might be the culprit.
Previous research had hinted that pigeons could incur foot damage from bacterial infections caused by standing in their own poop. But a closer look later revealed remnants of strings and often human hair caught between the digits, according to research published in 2018 in the journal Natures Sciences Sociétés.
By observing 1,250 pigeons along 46 blocks in Paris, researchers at the Center for Ecology and Conservation Science in Paris found that 20% of the birds were missing at least one toe. Matching these numbers with data on human activity and pollution at the level of city blocks, the researchers found more missing-toe pigeons in areas with high concentrations of hairdressers as well as densely populated blocks with high air and noise pollution.
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Traffic movement in these blocks could transport hair strands and plastic strings used to tie garbage bags to larger areas where pigeons encounter those objects, said Frédéric Jiguet, an ecologist at the Center for Ecology and Conservation Science and lead author of this study, published in the December issue of the journal Biological Conservation.
As pigeons strut across pavements and cobbled streets, their feet can get tangled in human hair. "It's not easy for them to take it off with their beaks," Jiguet told Live Science, referring to the strands of hair. "The more they try to take it off, the tighter it gets around the toe."
The strangling hairs restrict blood flow, potentially causing the pigeon's toe to fall off.
Such foot deformities could affect pigeons' movement and access to food in urban spaces. Researchers said the injuries could also affect reproduction in the species, as missing toes could cause males to lose their balance while on top of female birds during copulation.
In future studies, the research team hopes to place sticky mats across the city to get an actual measure of how much hair these urban birds encounter, the scientists said. They also want to see if foot damage in pigeons across other large cities is similarly linked to humans.
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Originally published on Live Science.
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Priyanka Runwal is a California-based freelance science journalist. She has a master's degree in Biodiversity Conservation from the University of Oxford and a master's in Science Communication from the University of California, Santa Cruz. She covers news and field-reported environment stories in the U.S. and India. Her work has appeared in The NYTimes, Science News, Science, Mercury News, Mongabay and The Wire.
This is totally plausible. Having chickens and other fowl has shown me that, if there is something they can find that has blown in from wherever, which they can get tangled in, they will manage to do so. I have had birds lose toes before, before I knew to watch for such things. I even had one unfortunate young turkey poult lose a lower leg from a piece of fishing line that blew in from someone's trash! It basically cut right through the joint, and when I found her, she was being attacked by the other birds, like the little feathered velociraptors they are. 🙄Reply
I fought to save that poor dear for months, trying to help her heal up the stub enough to fit a fabricated lower leg onto her stub! The two vets I called simply said to put her down, but she had such a will to live, and was so happy when she got cuddle time, that I could not possibly consider taking away her chance to survive
She broke my heart, though, by apparently getting a fast-acting new infection that I didn't catch in time. I literally cried, and suffered guilt, for months! I blamed myself for so long. Thinking maybe I should have saved her the suffering. Thinking I should have caught whatever infection she picked up soon enough to treat it like I did the previous two I had beaten. I still fear I was at fault, and I could have somehow done something to prevent losing her!
Anyway, enough of my continued guilt about my poult. It's just that loose string and hair and other trash versus birds is a bad mix for the birds. I didn't mean to go on so much about my pretty turkey poult I lost to trash entanglement. It brought back unpleasant memories, I must admit. I simply meant to say that this is extremely logical, as I have seen what can happen, myself.