With Priss now it's fairly easy - he will croak at the slightest provocation. He also trys Amplexis with anything that moves when the rain is on (poor Jeffery discovered this the other day - so did Tori's leg and even William, one of the Spotted Grass frogs (Limnodynastes Tasmaniensis) who share the enclosure.
But when they're younger it's a little more tricky - there are MINOR differences in the structure of their hands and the throat - these are very difficult to spot in a moving slipery creature. During the breeding season (December to march in southern hemisphere) the nuptual pads will show up - that's a definate and easy to spot indicator of a boy - mature females will develop eggs which can be seen through the skin of the abdomen (usually easiest to see as they climb the glass - a darkened area of sometimes defined black blobs seen through the skin of the lower body sides) - but if your frog friends are immature then the eggs will not be there and the nuptual pads will not go dark brown (although they will turn up as a raised portion of green at the base of the thumb))
However the responding to recorded croaks is allways a good bet - I can send you a couple of WAVs to play to them - If you want them then email me @ spq@va.com.au
4 2 1 (litoria Caerulea)
2 0 0 (litoria Aurea)
2 2 5 (Limnodynastes Tasmaniensis)
2 2 0 (Limnodynastes Fletcher)
2 ? ? (Limnodynastes Interioris) (not enclosed)
1 1 0 (Homosapien caucasious)