Just when you thought avian protests couldn’t get any classier than Cockatoo Eating A Croissant on a “no stopping” sign, researchers have discovered that in some places, birds are using metal spikes meant to deter them as nesting material. Seems humans’ attempts to make anti-bird spikes have worked a treat.

The metal nests don’t look exactly comfortable but may come with the benefit of protecting their eggs from other birds and predators. And as incorporating human-made materials into nests goes, they look cool as hell.

Crows are famously bold birds (not to be confused with ravens, though both are smart) that have been wowing with their extreme nesting materials as far back as 1933 when they were documented using barbed wire. In the proceeding decades, all manner of trash has rocked up in the nests of various bird species, but a new paper marks the first well-documented case of anti-bird spikes being used as nesting material.

Ripping off anti-bird spikes has been seen in a number of species, including Carrion crows in Rotterdam, The Netherlands, and Eurasian magpies in Belgium and Scotland. Now, it seems some are going a step further to incorporate them into their nests where they may even serve a functional role beyond just infrastructure.

“Magpies may use the anti-bird spikes not just as ordinary nest material, but specific placement in the dome, overarching the nest, hints at functional use,” write the authors of a new study. “The anti-bird spikes may be used by birds in the same way as they were intended to be used by humans: to ward off (other) birds.”

It’s probably the one thing the creator of anti-bird spikes didn’t want to happen.

It’s a smart move on the part of these famously clever birds, as magpie nests are predated by crows. Typically, they use thorns to keep hungry birds at bay, but as we are shifting into an era where the face of the planet is changing due to human activity, seeing human-made objects as functional parts of habitats may become increasingly common.

“In the Anthropocene, now that living biomass is outweighed by anthropogenic mass, alternative nesting materials are increasingly being adopted by urban birds," the authors explain. "With birds even using bird deterring materials like anti-bird spikes as nesting material, anything may become part of a bird’s nest.”

For those unfamiliar with the phrase, the Anthropocene has been designated an epoch in which humans are influencing the climate and environment, although it will be a long time before anyone knows if this is the right decision. The longest geological categories are Eons, followed by Eras, which are broken down into periods that in turn consist of epochs and ages. Whether or not humanity will be around long enough for our dominance to qualify as an epoch remains to be seen, but if we’re all gone it seems the point could well be moot.

In which case, we defer to our corvid overlords.

We spoke to researcher Auke-Florian Hiemstra to find out more about the novel nest designs.

How well do these bird spikes function as nest material? Are they safe for fledglings?

I think they work really well! Bird spikes are designed to keep birds away, and that may be exactly what the magpies are looking for. We even share the observation of barbered wire and even, and I think this is hilarious, knitting needles being incorporated into the dome of a magpie. Isn't that just fantastic? That must be one lucky magpie. The Antwerp nest looks like a bunker for birds, it has 1,500 sharp nasty metal spikes, that is 50 meters [164 feet] of anti-bird spikes!

I don't think the fledglings are harmed by the bird spikes, they have a specific placement within the nest, placed on the roof. The young ones are in the middle of the nest, feeling very safe, being guarded by 1,500 metal spikes, and here in the middle is the nesting bowl which is made out of twigs and soft materials. Magpies have a small opening in their nest in which they go in and out.

You've worked on other strange things that have turned up in nests, can you tell us about a few?

My definition of "nesting material" is quite a broad one. Coots in the canals of Leiden make their nest of plastic pollution, so of all the trash they can find. I always said: "almost everything can become nest material", but after I saw these birds using the anti-bird spikes I now know for sure: everything can become part of a bird’s nest!

What do you enjoy most about studying nest-building behavior?

I study "animal architecture" and I can really admire these beautiful structures they make. My research on bird nests really shows how dramatically our world has changed. Naturalis has a collection of more than 42 million natural history objects and has a big nest collection of thousands of nests, some collected 200 years ago. Then everything they build was natural, that birds now make nests with trash and plastic pollution really reflects how we humans have changed our world.

What are you working on next?

It would be really cool to analyse more anti-bird spike nests. And to see if they use these spikes purely as a replacement for thorny branches, or if these anti-bird spikes would work even better! That would bring an evolutionary advantage then to switch to this artificial material! But for that, we need more observations, and there must be many more nests like this!

If there are many people together, there must be many pigeons around, resulting in many bird spikes, which may lead to a magpie thinking: Mmm, I can use that material! I think it's funny that all these nests which are world news now, were found in the middle of big cities.

That's the fun of urban ecology! Even in the middle of a big city, you can find something that no one has ever seen!!

The study is published in Deinsea.