Down at our local pond today there were dozens of Bufo bufo, all male, the females will turn up later. It reminded me that as kids we would catch the males by gently shaking a stick in the water, they would grab hold and could be lifted out. If you use two fingers to gently hold them just infront of their back legs they croak a call that is supposed to let other males know they have made a mistake! I would love to know if the American species do the same.