There are magpies that use spikes to repel other birds. – writes on the ScienceNews website.
In Antwerp, Belgium, a gnarled hollow is seen on a sugar maple tree, from the center of which no fewer than 1,500 long, sharp anti-bird shafts point outward. It’s a veritable lair for birds, says biologist Auke-Florian Hiemstra. It’s like an impregnable fortress.
The nest is one of five spiked anti-bird nests found in Europe. Heemstra and a colleague reported this phenomenon July 11 in Deinsea, the online journal of the Natural History Museum Rotterdam. Pointy strips of bird repellent usually line the friezes in cities around the world. Now they line up at some bird’s house.
The study began when a patient at a hospital in Antwerp looked out his window and saw the nest in question. He sent a photo to Hiemstra, who is researching nests and plastic pollution at the Naturalis Center for Biodiversity in Leiden, the Netherlands. After the breeding season, Heemstra and his team traveled to recover the nest and bring it back to the lab for study. When he wrote his account of the nest, he received advice about four similar nests in towns in Holland and Scotland.
The nests belong to magpies (Pica pica) and crows (Corvus corone). Crows use thistles as part of their nest structure. But Hiemstra believes magpies use it for what it was originally intended for: to ward off other birds.
Magpies are relatively small, so they build domed roofs over their nests to protect their eggs and young from birds of prey. Magpies often decorate their roofs with thorny branches for extra protection. But in big cities, thorns are hard to come by, so magpies get creative with whatever materials they can get their hands on, like nails, screws, or knitting needles. Researchers say anti-bird spikes serve as the ultimate replacement for the Anthropocene.
The observation is fascinating, and the application of citizen science commendable, says Zuzana Jagiello, an ecologist at the University of Warsaw who was not involved in the study. But he believes the paper lacks field experiments or observations to claim that spikes are used as a deterrent to birds in magpies’ nests. This is a starting point for a deeper exploration of the phenomenon.
Hiemstra ro With enough nests, you might even be able to study whether spikes improve the survival of young magpies.
(Source: ScienceNews: https://www.sciencenews.org/)
