Birds take revenge on humans with clever new trick
Anti-bird spikes are a common sight on many buildings but urban birds have turned the tables on us by developing an ingenious way of building nests.
The birds are taking the sharp metal spikes meant to scare them away and using them to protect their nests.
Researchers from two Dutch natural history museums collected nests of a carrion crow and a Eurasian magpie that were largely built with anti-bird spikes.
Researchers from Naturalis Biodiversity Center and the Natural History Museum Rotterdam have explained this remarkable behaviour as ‘an ultimate adaptation to life in the city’ in the scientific journal Deinsea.
‘It’s like a joke, really’ said biologist Auke-Florian Hiemstra of Naturalis. ‘Even for me as a nest researcher, these are the craziest bird nests I’ve ever seen.’
‘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 Kees Moeliker, director of the Natural History Museum Rotterdam and co-author of the scientific publication.
It started with the discovery of a huge nest in Antwerp, in the courtyard of a hospital, which was spotted by one of the patients. High up in a tree, magpies made a huge nest of up to 1,500 metal spikes.
For this particular nest, birds pulled as many as 50 meters (150 feet) of anti-bird pins from the eaves.
‘An impregnable fortress’, said Hiemstra, ‘because the magpies appear to be using the pins exactly the same way we do: to keep other birds away from their nest.’
Anti-bird spikes are often used in city centres to deal with large flocks of pigeons and are placed on rooftops and ledges of buildings.
Magpies make a roof on their nest to prevent the robbery of eggs and young, and they specifically look for thorny plants for this purpose. Now, magpies in cities are using anti-bird spikes to keep hungry egg robbers away.
‘They are literally made to keep birds at bay,’ said Hiemstra, ‘which is how they seem to be used by birds as well.’
It’s not just one pair of magpies that have figured out a creative use of these spikes. The article describes several magpie nests built with anti-bird spikes seen in the Netherlands, Belgium and Scotland.
Other sharp materials, such as barbed wire and knitting needles, are also used by magpies for the roof of their nests.
Crows also seem to be able to build nests with anti-bird spikes, with the spikes pointing inwards so they do not harm the bird.
It’s a known fact that birds are rebellious creatures and these sharp objects don’t scare them. In 2019, a video of a crow removing bird spikes from its perch went viral as a symbol of nature fighting back against humans.
The large magpie’s nest of anti-bird pins from Antwerp can be seen from 11 July as a new highlight in the LiveScience room of the Naturalis Biodiversity Center in Leiden, Netherlands, which can be visited free of charge.
The Natural History Museum Rotterdam has the crow’s nest of anti-bird pins on display in the recently opened ‘National Park Rotterdam’ exhibition, along with several other remarkable constructions of urban animals.
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