You've no doubt seen the metal spikes that are placed on the outside of buildings to keep birds from roosting. Well, it has been discovered that magpies and crows are actually using those spikes in their nests – appropriately enough, to keep other birds away.
The very ironic use of such a nesting material is the subject of a study recently conducted by scientists from the Netherlands' Naturalis Biodiversity Center and the Natural History Museum Rotterdam.
It all began when a patient at an Antwerp hospital spotted a large and unusual magpie nest, high up in a tree in the facility's courtyard. Upon closer examination, that nest was found to contain approximately 1,500 anti-bird spikes. They had been pulled by the birds, from about 50 meters (164 ft) of the hospital's eaves.
The magpies placed the spikes so they protruded outward from the roofed nest, in order to discourage other birds from going in and eating the eggs or chicks. Magpies and other related birds regularly use other sharp building materials, such as barbed wire and thorny branches, for the same purpose.
Speaking of other members of the corvid family, the researchers also documented a Dutch carrion crow's nest which incorporated the spikes. What's more, it turns out that magpies have already been seen using the spikes in other parts of the Netherlands, and in Scotland and Belgium.
"It's like a joke, really" said biologist Auke-Florian Hiemstra of the Naturalis Biodiversity Center. "Even for me as a nest researcher, these are the craziest bird nests I've ever seen."
A paper on the research was recently published in the journal Deinsea. The original spiky magpie nest can currently be seen in Naturalis' LiveScience room (free of charge), while the crow's nest is on display at the Natural History Museum Rotterdam.
Source: Naturalis Biodiversity Center