Great advice, friendly people, and lots of frogs!
Bertie's sides were contracting in and out twice and at the same time there was a medium-pitched, broken croaking sound. I didn't see his throat so I can't be sure it was him but I'm sure the sound and his sides moving were simultaneous! He's only about 10-11months old but it seems we may have a boy! We'll find out for sure in the next few months