A Bird’s Sense of Irony

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Crows and magpies are building heavily fortified, near impregnable nests using anti-bird spikes, a discovery that scientists have called “the ultimate adaptation” to city life, the Independent reported.

The bird species belong to the Corvidae family, which are known for their superior cognitive skills, including the ability to use sticks and stems as tools.

In a new paper, Dutch biologists reported finding a number of nests made up of anti-bird spikes across the Netherlands and Belgium. Those spikes are usually placed on the eaves of buildings to keep birds away.

Researchers said that one nest had up to 1,500 metal spikes. They noted that these spikes served a defensive purpose – “to keep other birds away from their nest.”

“Just when you think you’ve seen it all after half a century of studying natural history, these inventive crows and magpies really surprise me again,” said study co-author Kees Moeliker.

Moeliker and his team noted that anti-bird spikes weren’t the only material: Some magpie nests were made up of barbed wire and knitting needles.

Birds are known to use a number of discarded objects to build their nests, including face masks, cigarette butts and sunglasses.

Still, this is the first time that birds have been found to use the very material deployed by humans to deter them as nesting material.