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It’s widely known that crows, ravens, and magpies are remarkably intelligent creatures. They’ve been observed using tools, are thought to recognize themselves in a mirror, and may be able to identify complex patterns.
But there’s still plenty about corvid behaviour that shocks even the most knowledgeable ornithologists. One such example was recently discussed in the Dutch journal Deinsea, a publication of the Natural History Museum Rotterdam. In an ironic twist, researchers found that birds had pulled up the strips of thin metal spikes meant to deter them from perching on buildings and other manmade structures.
And they didn’t stop there. Rather than being deterred, the crows and magpies clearly liked the look of the spikes and incorporated them into their nests, seemingly to protect themselves against predators or give structural support to their constructions.
Interestingly, the anti-bird spikes were used differently by different species. The researchers, who focused on examples in Scotland, Holland, and Belgium, observed magpie nests with spikes facing outward as a form of defense, whereas crows turned the spikes inwards.
- One magpie nest in Antwerp was found to have around 165 feet (50.3 m) of anti-bird strips, totalling over 1,500 spikes. The nest was found in a hospital courtyard, so the magpies clearly had plenty of anti-bird spikes to choose from on the hospital roof.
- There are a few potential downsides to using manmade materials instead of natural materials such as twigs and branches. The metal could be too cold for young chicks, and birds could unwittingly bring toxic substances into their nests. Manmade materials could also be easier to spot than well-camouflaged natural materials.
- Using human-made materials is certainly not unique to corvids, though the irony of birds using anti-bird spikes to build their nests is particularly satisfying. An unrelated study also published this month found evidence of items such as straws, candy wrappers, and plastic bags in the nests of 176 bird species, spread across the globe.