The sight of dozens of butterflies congregated in one spot might be beautiful, but if you know what they’re actually doing, you might not want to get too close. When butterflies get together like this, it’s usually to slurp up some nutritional goodies from an unexpected source—like, oh I don’t know, animal pee.

This behavior is often called “puddling” or “mudding”, though the insects don’t just suck on damp earth. To get missing nutrients like sodium which aren’t common in the nectars the