National Geographic : 1950 Apr
© National Geographic Society 515 Kodachrome by Arthur A. Allen Mate-calling, Big Western Toad Balloons His Vocal Sac and Blows a Minute-long Blast The klaxonlike call can be heard on a warm, still evening over half a mile across the Great Plains. A chorus of the harsh, low-pitched trills may reach twice as far. Almost deafened, the author dubbed this species (Bufo cognatus) "the boiler factory toad." Air driven back and forth between lungs and closed mouth twangs his vocal cords. The sac acts like a sounding board. Only male toads and frogs trill; females are usually silent.