Social Signals and Behaviors of Adult Alligators and Crocodiles

We compare and contrast the signalling systems and social behaviorsof Alligator mississippiensis, Crocodylus aculus, and Crocodylusmloticus. Our qualitative analysis focuses primarily on thebehaviors of adults during three phases of reproduction: I.Defense of Territory and Courtship, II. Nesting and Incubation,and III. Hatching and Post Hatching. Signals and signal elementsare very similar among the three species. For example, all havevocal, non-vocal acoustic, and visual signals, some transmittedthrough air or water and others through both media. In addition,each species' repertoire is composed of discrete, graded andcomplex signals. A few signals are unique to each species. However,their signalling systems differ in the temporal organizationof the behaviors, and in the relative frequency in which certainfunctional groups of signals occuror in which signals occurin a particular sensory mode. Apparently, the signalling systemsof C. acutus and C. niloticus are more similar to each otherthan either is to the signalling system of A. mississippiensis.The signalling systems of the crocodile species appear to beadapted to open water habitats in which visual signals are advantageousand to high density breeding groups and post-copulatory intersexualcontact. In contrast, the Alligatorsignalling system appearsadapted to a marsh habitat in which vocal signals are likelyfavored and to low density breeding groups.