I believe it's 90-120 days and they can retain sperm from the previous summer/fall, so could be even longer Glad to hear you're releasing Tina and most of the babies. I think you've made a good choice in the two "easy feeders." Hopefully your son will understand. Maybe talk to him about how Tina is used to being free. Make some comparison to something important to him, like what if some stranger picked you up and you never got to come home... although that one might be a bit too scary for him, just come up with something important to him that he would miss if he couldn't do it anymore. Then compare the babies to human babies being adopted. You guys will be their new mom and dad. Seems kind of corny, but if you can find a way to make the connections in his head to things he's already familiar with so that he can understand why you're releasing Tina he'll feel like he's doing a wonderful, unselfish thing, instead of just something mom and dad made him do.