A leopard frog gets ready to hibernate for the season along the Green River. The hibernation period begins in October or November and continues through March. Northern leopard frogs may bury themselves in muddy lands or swim to the bottom of semi-frozen lakes in order to hibernate; hibernation may also take place in caves. The creatures live for an average of somewhere between 5 and 8 years. They sound like a small motor boat engine, and will scream loudly when frightened or captured.