Some bird nests are getting pretty metal.

Crows and magpies in Belgium and the Netherlands have constructed their nests using anti-bird spikes metal skewers that people place on buildings and sometimes even on trees to prevent birds from gathering there.

Even for me as a nest researcher, these are the craziest bird nests Ive ever seen, tweeted Auke-Florian Hiemstra , a biologist at the Netherlands Naturalis Biodiversity Center and lead author of a scientific paper on the phenomenon published in the journal Deinsea this week.