Birds using humans' anti-bird spikes to build their nests: Dutch researcher

Birds, specifically magpies, are using the spikes humans install on their balconies and roofs to keep birds away to build and protect their nests, Dutch biologist and researcher Auke-Florian Hiemstra discovered. “That they use it so cleverly is insane,” he told RTL Nieuws. “That anti-bird material is used to make a nest, which in turn creates more birds, I find that hilarious.”

Magpies always use sharp items to keep predators and other birds away from their nests, but thorny plants are often hard to find in cities. So they’ve turned to humans’ anti-bird spikes. “The cool thing is that those magpies take the spikes off roofs and place them on their own nests.”

Hiemstra doesn’t know how long magpies and other birds have been doing this. The nests he studied date from recent years. But it could well be that no one has noticed it before, he said.

He found one magpie nest made with hundreds of spikes in the courtyard of a hospital in Antwerp. “You can still see a trace of glue on the roof, where the spikes used to be,” he said. “The magpie pried it loose.”

While the anti-bird spikes apparently don’t work well to keep magpies off roofs and balconies, they are very effective for protecting nests, Hiemstra said. “Landing on such a nest to steal eggs or youngsters becomes a lot more complex if all those sharp spikes stick out,” he explained. “1,500 metal spikes, 50 meters of anti-bird material in one heap. You really don’t just enter there as a crow.”

Hiemstra also found other materials birds used to protect their nests, including barbed wire. “My favorite is a magpie that used knitting needles in the roof of the nest. I think he came home very happy, like: look what I’ve found,” he said. “It’s such rebellious behavior. I cheer for the birds.”

The nest from the Antwerp hospital is currently on display in Naturalis.