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Rebellious birds use anti-bird spikes to build their nests

Biologists have long known that many species of birds use human-made, often sharp materials to build their nests. With the first report of a crow’s nest made of barbed wire dating back to 1933, and recent observations of the use of materials such as nails, screws, and even drug users’ syringes in nest building, birds seem highly proficient in adapting to urban life by taking advantage of a variety of anthropogenic objects they find in the environment. 

Now, a team of researchers from the Naturalis Biodiversity Center in Leiden and the Natural History Museum in Rotterdam has discovered an even more surprising and innovative type of bird nests, made – quite ironically – from anti-nesting spikes.

Crazy bird nests

In cities, anti-bird spikes are found on many buildings. Although these sharp metal spikes are used to scare away birds, and stop them from building nests, the scientists have recently collected nests of a carrion crow (Corvus corone) and a Eurasian magpie (Pica pica) that were largely constructed with these materials originally designed to deter birds. 

“It’s like a joke, really,” said lead author Auke-Florian Hiemstra, a biologist at 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,” added co-author Cornelis Moeliker, the director of the Natural History Museum Rotterdam.

Using the tools to their advantage 

One of these nests was spotted in a courtyard of a hospital in Antwerp, Belgium by a patient. This enormous magpie nest consisted of nearly 1,500 metal spikes pulled from as many as 50 meters of anti-bird pins. “An impregnable fortress because the magpies appear to be using the pins exactly the same way we do: to keep other birds away from their nest,” Hiemstra explained.

Magpies usually look for thorny plants to construct roofs that prevent the robbery of eggs and offspring by other birds. However, urban life seems to be rich in other possibilities – not only for magpies in Belgium, but also for other species, such as crows, in the Netherlands or Scotland. Besides anti-bird spikes, other materials the scientists discovered include barbed wire, knitting needles, condoms, fireworks, cocaine wraps, windshield wipers, and sunglasses.

“This innovative use of bird spikes for nest construction can be seen as a modification of a pre-existing natural behavior and shows the flexibility of nest-building behavior and use of materials,” wrote the researchers.

“In today’s Anthropocene epoch, there is more anthropogenic material present than natural biomass, and it may thus not come as a surprise that these spikey alternatives are being adopted by urban birds. If even bird deterring material is used as nesting material, anything may become part of a bird’s nest today.”

The study is published in the journal Deinsea. The huge magpie nest discovered in Antwerp can be seen from July 11 as a new highlight in the LiveScience room of Naturalis, while a crow’s nest built of anti-bird pins is now featured at the Natural History Museum Rotterdam as part of the recently opened exhibition “National Park Rotterdam.”

More about bird nests

Bird nests are structures that birds create for laying eggs and raising their offspring. The size, shape, and materials used for the nest vary greatly depending on the species of bird.  

Types of bird nests

Cup nests

These are the typical nests most people envision when they think of bird nests. They are usually built in the forks of trees or shrubs and are shaped like a cup. They are often made of twigs, grass, and mud, and are lined with soft materials like feathers or moss. Examples of birds that build cup nests include robins and finches.

Platform nests

These nests are usually larger and flatter than cup nests. They’re often built on tree branches or on the ground, and can also be found on human structures like telephone poles or buildings. Eagles, hawks, and ospreys typically build platform nests.

Cavity nests

Some birds prefer to nest in cavities, which can be natural (like a hollow in a tree) or man-made (like a nest box). They may also excavate their own cavities in softwood trees or termite nests. Examples of cavity nesters include owls, woodpeckers, and some species of ducks.

Pendant nests

Some birds, like the oriole or weaver bird, construct elaborate hanging nests that resemble a pendant. These nests are woven from plant fibers and hung from tree branches.

Mound nests

Certain bird species, such as the mallee fowl and brush turkey, build large mound nests on the ground. These nests are often made from leaves, soil, and compost, and they use the heat generated from the composting process to incubate their eggs.

Burrow nests

Some birds, like kingfishers and puffins, dig burrows in the ground, in riverbanks, or even in snowbanks for their nests.

Scrape nests

These are simple nests that involve scraping a shallow depression in the ground or on a cliff ledge. The bird may line the scrape with pebbles or vegetation. Many shorebirds, like plovers and gulls, make scrape nests.

Nests not only serve as a place for laying eggs and rearing young, but also provide some degree of protection against predators. Different bird species have evolved different strategies for their nests, reflecting the diversity of environments and survival challenges they face.


By Andrei Ionescu, Staff Writer

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