Grey tree frog . Ever hear these? | Kyle Underwood photography

Watch this video with sound! Have you been hearing this sound? It is the hearty, resonating trill of the gray tree frog, which you will most likely hear during the late spring and summer months, especially on warm humid days and nights. Many people unknowingly mistake the frog's loud call for that of a bird, similar to how the call of a wood frog is often mistaken for feeding ducks. The gray tree frog is a true master of camouflage, so it is more often heard than seen. Thanks to Carl Lovisolo fo

Every summer about this time, gray tree frogs converge on Iowa ponds for mating and egg-laying, and with hundreds of frogs involved, the calling becomes a roar. They are commonly heard in forests from late spring to mid-summer, especially on quiet rainy days, but more frequently at night. Around these small breeding ponds, however, is probably the only time you'll hear them in super-concentrated numbers. The video doesn't do the overall noise level justice, because it is truly deafening. | Iowa