How old were they when they started 'chirping'? I raised from egg and released 130 Cope's Grey over last summer. When the first cold snap came the first of Nov. I still had 5 and REFUSED to let them go in the cold! So...they spent a very nice snuggy winter inside being VERY well cared for. I'm suspecting 3 were female (Bertha, Lulu and Clara) and 2 male (Bert and Ernie). We released them the day after Mother's Day this year, so give or take they were about 7-8 mo. old. So far this year I've got 6 in the 'nursery' that are about 3 wks. old and later today will transfer 4 more in. They've got all their legs, tail is gone and climbing up the sides of the 'morph container'. There are literally HUNDREDS more in various stages. It's a labor of Frog Love.