Crows and Magpies use anti bird spikes in their nests.

[Catherine]

Buildings all over use metal spikes to keep birds from landing. Crows and Magpies have been pulling up these spikes and using them in their nests. They seem to be using them as protection for their nests, the way we protect our buildings.

https://ca.style.yahoo.com/crows-magpies...43425.html

Crows and Magpies are very clever. I think they probably do know what they are doing. The spikes are positioned in a way that protects the nest.
It makes you wonder what other things they are going to learn to use.