Makes you wonder how much of life "happens" in the UV and infrared spectrums that we can't see.

Does this let squirrels recognize each other in a dark forest without alerting predators? If so, did the predators adapt to that? It doesn't sound too uncommon from the other comments, but how much do the fluorescing wavelengths change? Is this another dimension of camoflauge and/or advertisement that we literally don't see?

Or is it just one of those weird things?