Ack-Florian Hiemstra, a biologist who studies how wild animals reproduce human material, thought he had seen it all. In his research on the common coot, a water bird common in Dutch canals, he found nests containing windshield wipers, sunglasses, plastic carnations, condoms and envelopes used to package cocaine.
“So my definition of what constitutes a nesting material is already quite broad,” says Mr. Hiemstra said. “Almost anything can be part of a bird’s nest.”
However, he wasn’t prepared for what he found in July 2021 when he went to investigate a strange nest outside a hospital in Antwerp, Belgium. A Eurasian Magpie nested in the top of a sugar maple tree. A cyberpunk hedgehog, with thin metal rods sticking out in every direction.
“I couldn’t believe my eyes,” he recalled. “These birds make nests with anti-spikes.”
Rows of these sharp metal pins have become a common feature of urban environments, installed on roofs and ledges to discourage birds from roosting or nesting on buildings. But outside the Antwerp hospital – where, as it happens, many of the roof spikes are missing – the magpies have managed to turn the hostile architecture into a home.
“They’re outrunning us,” Mr. Hiemstra said. “We’re trying to get rid of the birds, the birds are collecting our metal spikes and actually making more birds in these nests. I think it’s just an amazing comeback.
And the Antwerp Magpies were not alone. Over the next two years, Mr. Hiemstra and his colleagues discovered several other nests built by Eurasian magpies and carrion crows that had anti-bird spikes. They described their findings in a paper published this week in the journal Deansee.
“It’s absolutely fascinating,” he said Mark Mainwaring, an expert on bird nests at Bangor University in Wales, was not involved in the new study. “It shows how intuitive these birds are and a certain amount of flexibility to find these new things and use them.”
Magpies and crows are members of the corvid family, a group of birds known for their intelligence and problem-solving skills. Magpies often build dome-shaped nests, attaching thorn branches to the roofs designed to protect against predators. Mr. In the nests found by Hiemstra and his colleagues, magpies use anti-bird spikes for the same purpose, turning them into a spiky nest cover.
“The Antwerp nest is really like a bunker for the birds,” says Mr. Hiemstra said, calculating that he had about 50 meters worth of anti-bird strips and 1,500 visible spikes. “It’s really safe to sit in the middle knowing there are 1,500 metal shards or pins to protect you.”
Although the researchers did not catch the magpies in the act of tearing strips from the hospital roof, spikes disappeared from the area near the birds’ nests, and other birds were observed tearing such spikes from buildings. And scientists note that sharp, human objects, including barbed wire and knitting needles, have previously been found in magpie domes. (“It must be a happy magpie coming home to the nest with this big knitting needle in its beak,” mused Mr. Hiemstra.)
Crows used spikes differently by driving sharp pins into the nest. Although the idea has not been proven, placing the spikes in this way may provide more structural support for the nest, Mr Hiemstra hypothesized.
It is not entirely clear whether the birds are simply using the spikes because they are available – in the urban forest, they may come more easily than thorny twigs – or whether they may be better suited for the job than natural materials.
But the use of artificial nesting materials is common throughout the avian universe, Dr. That’s according to a new review of the scientific literature by Mainwaring and his colleagues, published Monday in the journal Philosophical Transactions of the Royal Society B. They found reports of tens of thousands of nests — built by 176 different bird species, on every continent except Antarctica — containing artificial materials including plastic bags, strips of clothing, fishing line, paper towels, dental floss, rubber bands and cigarette butts. .
“Where there’s an opportunity to install man-made things, man-made things, in your nest, you’re probably going to do it as a bird,” said author Jim Reynolds, an ornithologist at the University of Birmingham in England. A new review. “Some of this raises eyebrows among our field ornithologists, because you think, really?”
The findings reflect how much trash humans leave behind, Dr. And research indicates that the use of artificial nesting materials is becoming more common, Reynolds said.
Long-term effects are unknown. Shiny or colorful objects can help a bird attract a mate – or attract the attention of predators. Research suggests chemicals in cigarette butts help protect nests from parasites — but are toxic to birds. And there are many reports of chicks entering the nest after being entangled in plastic string or twine.
Regarding the use of anti-bird spikes, Dr. Mainwaring was curious to see “if the behavior spreads, if other magpies see their neighbors using these spikes in their nests and think, ‘How do you build a nest?’ “And even the offspring raised in those nests grow up thinking it’s completely normal and natural.”
Mr. Hiemstra suspects there are more spike nests there. They certainly think there are.
“I’m definitely rooting for the Birds, cheering for the Birds and enjoying the fact that the Birds are fighting back a little bit,” he said. “Because they deserve a place in the city just like us.”
