Vocalization in juvenile crocodilians.

Evidence is presented that the grunts and distress calls of juvenile alligators (Alligator mississipiensis) are examples of graded calls, which are given in different form depending largely on contest. Representative sonagrams of the distress calls of three other species of crocodilians (Caiman crocodilus, Crocodylus niloticus, and Crocodylus siamensis) are presented and compared with sonagrams of alligator distress calls. These findings are discussed in light of current knowledge of the bioacoustics of other vertebrates.