In many cities around the world, anti-bird barbed traps are used to protect statues and balconies from birds. However, the birds now seem to have found ways to take advantage of these traps used against them.
Dutch researchers discovered that some birds use pointed objects as weapons around their nests and use them to keep pests away, just as humans do. Birds show incredible adaptability, says biologist Auke-Florian Hiemstra. “These are incredible castles – like a haven for birds,” he said in an interview with the BBC.
The use of man-made objects in bird nests is nothing new. There is evidence worldwide that many species use everything from barbed wire to knitting needles. Still, research by the Naturalis Center for Biodiversity and the Natural History Museum Rotterdam stands out as the first well-documented study that says birds position sharp spikes outward, maximizing protection.
Hiemstra’s research began in the courtyard of a hospital in Antwerp, Belgium, where a huge magpie nest containing about 1,500 spines was found. “For the first few minutes I stared at this strange, beautiful, strange nest,” Hiemstra said. “I saw the spikes pointing outward and forming a perfect armor around the nest.”
A trip to the hospital roof confirmed this. Strips of anti-bird nails had been torn off about 50 m from the building, leaving only traces of glue.
A larger, completed nest is located in the museum in Rotterdam and in the collection of the Naturalis Biodiversity Centre. Hiemstra says a lot more needs to be found to fully prove his theory, but there are a few features of the nest structure that suggest that birds use pointed traps as protection.
“So they don’t just make a roof – they create a roof made of barbed material for protection,” he says, noting that the first of these is that the spikes are on the roof of the nests.
Birds often use thorny branches to protect their nests, Hiemstra says, but because people don’t like such shrubs and trees, residential birds prefer the next best thing, man-made spikes. He also adds that the birds are remarkably adaptable to their surroundings, as well as showing how determined they are to protect their nests, as strong glue is used to attach the spikes to the buildings and the spikes are not easy to remove.
While this may be seen as a nuisance for people who pay to set up sharp objects, Hiemstra describes it as a “nice revenge”: “To keep them away, they use the material we produce to build nests to build more birds.”
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