The Role of Habitat in Crocodilian Communication
Ph.D dissertation, defended April 1, 2011. Vladimir Dinets

Abstract. For full text please see

All crocodilian species have a particular category of signals, which are used as advertisement calls during the mating season. Each such call is a combination of a few components with different physical properties, such as body postures, vocal calls, headslaps or jawslaps, and infrasound vibrations. These components differ in their capacity to carry information about the animal's status and location, and their use can be expected to be adapted to habitat structure. In particular, vocal sounds should be used more in fragmented aquatic habitats where they are more effective, while slaps should be used more in continuous aquatic habitats. A comparison of signaling and preferred habitats by extant crocodilian species confirmed this prediction. Also, in species that are habitat generalists, animals in populations inhabiting only continuous aquatic habitats were found to use more slaps, while animals in populations inhabiting only fragmented aquatic habitats used more vocal sounds. But in populations inhabiting mixed habitats, individual animals did not adjust their signal composition to habitat parameters, indicating that the observed differences between populations and species are evolved adaptations. In the course of the study, novel information on signaling was obtained for many crocodilian species, providing insights into their ecology and evolutionary history.