I bought two breeder mice about two weeks ago. Both are white with red eyes, one is male the other is female.

I just noticed today while refilling their food bowl that the little girl had a patch of fur missing behind her neck. Kinda looks like the little boy was nibbling on her neck.

Do they do that with breeding? The little boy has a very small patch missing on his shoulder blade which leads me to believe rough play. But does that all coincide with breeding?

Thanks all!