Why Clean Out Nesting Boxes?

I'm reluctant to potentially disturb residents, but this squirrel expired at home. This is the closest Bishop will ever get to one, as he is slow to catch the living!

Gnawed Nesting Box

This is a flying squirrel box. The entry hole is on the upper left, to allow gliders access from a tree trunk. A gray squirrel enlarged the hole. Moral: always buy boxes with reinforced holes!