I have a grey Tree Frog as a pet. His name is tubby. I rescued his sisters and brothers and some of his froggy friends from my pool. I do it every year. When they turned to frogs I released them back into the wild. if you had them over winter I would wait until you can hear the Grey Tree Frogs calling outside. Than release them. I would release the one s that have all of their legs. The ones missing legs will not survive. they will be eaten or die on their own. so I sugest you keep those ones. you can give them a fighting change to survive.