Man makes life difficult for many animals, but there are also species that do not give up, that even manage to use the omnipresence of humans for their own purposes. Magpies and crows, known for their high intelligence, also seem to poke fun at these strange two-legged creatures that cannot fly but build their dwellings high in the sky.
At least that’s the impression the Dutch biologist Auke-Florian Hiemstra of the Naturalis Biodiversity Center in Leiden had when he first saw a magpie’s nest made of bird-repelling spears in the courtyard of a hospital in Antwerp. The pointy, sharp metal constructions are actually intended to prevent birds from building nests and are therefore attached to window sills and roofs. “Even for me as a nest researcher these are the craziest bird nests I have ever seen”writes Hiemstra on Twitter.
“They seem to use the skewers the same way we do.”
A closer examination of the wire nest revealed that the animal architects had installed around 1500 metal spikes. The male, who is responsible for procuring the building materials at Elstern, pulled bird repellent needles about 50 meters from a roof overhang of the clinic.
In a publication in Deinseathe online journal of the Natural History Museum in Rotterdam, Hiemstra and his team describe other similar finds: In Rotterdam, the Netherlands, crows had also used bird deterrent spears to build their nest. “While we were working on our publication, another magpie nest made of antibird wire was discovered in Glasgow, Scotland,” the researchers write. “And during the review process, we were told about another such nest in Enschede, The Netherlands.”
Nest researcher Auke-Florian Hiemstra with one of his research objects.
(Photo: Alexander Schippers / Naturalis)
The crows seemed to have taken a liking to the anti-bird spikes as they helped make the nest sturdy and stable. The magpies went one step further. “They seem to use the skewers the same way we do,” Hiemstra says, according to a press release from the Naturalis Biodiversity Center. “To keep other birds away from their nest.” The pointed, sharp-edged skewers would turn their nests into an “impregnable fortress”.
In fact, magpies prefer to build their nests inside thorny bushes. There, the eggs and young are well protected from nest predators – which include crows. If the clever birds build their nest in a less well-protected place, such as in a tree, they change the architecture: The nests then have a curved shape with a kind of roof that is supposed to protect the offspring from enemies from above. The entrance is narrow. To make the nest even more secure, magpies collect thorny twigs, for example from hawthorn bushes or sloes. “To do this, they fly up to five kilometers,” write the biologists.
When there are no thorn bushes, the magpies seem to find the pointed anti-bird skewers a viable alternative. Hiemstra and his team see it as “an ultimate adaptation to life in the city”.