What does his diet consist of? I hope much more than nuts. I’m sure your problem is more food aggressive related than hormones. It’s going to be a loooong winter if you don’t make some changes. I think you’re correct that it gets too cold to release before Spring, but others are more familiar with your climate than me. I wonder if there’s enough time before freezing temps set in for him to be released??
First, I’d eliminate all nuts. The very scenario you describe is why I don’t give any nuts till my squirrels are in the release cage. You’re going to have to cage him and search your house for stashes.
Edit: I looked up Frazier Farms and see that you purchased this squirrel, and you also have a grey squirrel? Did you purchase the grey one, too? So your plan was to not release either of them? I hope Frazier Farms guided you on the proper diet for squirrels. If not here’s the link.
https://thesquirrelboard.com/forums/...-Pet-Squirrels