Birds have employed human "weapons" against other birds, with fortress-like nests stunning scientists (photos included).

Human cities have long attracted other animals, which can find safe spots from predators among the high-rise buildings. The humans themselves do not always appreciate this cohabitation and try to protect their apartments with various devices, such as bird spikes. However, sometimes animals exploit our technologies for their own purposes.

In recent years, researchers have discovered that magpies use metal spikes to build their nests. This was reported in a study published in the Natural History Museum journal in Rotterdam.

While it is unknown exactly when magpies figured out how bird spikes work and how to use them to their advantage, the first attention to this phenomenon was drawn in 2023. At that time, biologist Auke-Florian Hemstra, while in a hospital in Antwerp (Belgium), noticed a peculiar structure in a tree, which he later described as an "impregnable fortress."

The "fortress" turned out to be a magpie nest constructed from 1500 outward-facing metal spikes.

"It's like a joke, really. Even for me, as a nest researcher, these are the craziest bird nests I've ever seen," he described the find.

After this, the scientist and his team turned to the internet for assistance and found even more examples of how birds use human "anti-bird weapons" for their own purposes. The researchers are confident that these spikes are used in the same way we do — to deter other birds.

Instances were found in Belgium, the Netherlands, and Scotland, primarily involving magpies and crows, which are considered some of the smartest birds in the world. Additionally, the feathered creatures have also realized that they can benefit from other sharp objects like knitting needles, barbed wire, and even syringe needles.

These are not the only human items being used as nesting materials. Other found objects include sunglasses, windshield wipers, plastic flowers, and even contraceptives.

"If even sharp spikes designed to deter birds are being used as nesting material, then apparently, these days, anything can end up in a bird's nest. Nothing could be crazier, right?" said Hemstra.

It seems that pigeons have also caught on, as their urban nests often feature distinctive protection.

As reported earlier, a pair of orcas managed to drive away all the great white sharks off the coast of South Africa. Meanwhile, in other regions, they have learned to hunt even whale sharks, the largest fish in existence today.