I have a female clown but I will probably get her a comanion this summer so hopefully I will get to hear some calling too. My clown was a bit of a scaredy cat when I first got her. It took about 3-4 months and now she is fine. She will still bolt when I open the cage and it is extremely difficult to catch her but she now will come out and sit on the leaves right up in front and look out. Give your other one a little time and I'm sure he/she will eventually come out of his/her shell and you will have two frogs looking to entertain you. Although, just watch out the frog hobby is very addicting...it's almost impossible to stop with just one species.