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

Finally got a good video of the gray tree frog croaking..  he gray treefrog is a species of small arboreal holarctic tree frog native to much of the eastern United States and southeastern Canada Fun fact.. Survives freezing temperatures by producing glycerol and maintaining slower metabolic processes | Kyle Underwood photography