I have been keeping dart frogs for several years, mostly D. tinc azureus and more recently a pair of green&black D. auratus. What got me started in the leaf business was a want ad for large quantities of Magnolia leaves. The up shot is that I traded about 40 cubic ft of leaves for four sub-adult Intermedius. I could never have afforded them and I am absolutely stunned by them.
Anyway, I've never once heard my azureus or auratus males calling. I did see the azureus male "call" once but didn't hear it.
Tonight one of the Imitators started to call and it was soooo cool.It was faint and I only heard it because I was sitting close to the viv, but I managed to ID the little guy. So, I know I have at least one male.
It's the little things that make me love this hobby so much.