How big or old do red eye's have to be to be able to call? Because i'm trying to figure out if mine are male or female but so far i've not heard them call at all. Its entirely possible however i'm sleeping through it...

I have a feeling i have a male and female, but not to sure. I've tried looking at the feet but Yatzee doesn't like me touching him to much, he's still not happy about me cleaning out his tank last week.