Geographic distribution, habitat, reproduction, and conservation status of crocodilians in the Americas

The chapter gives an introductory overview on the biology of the 11 species of crocodilians inhabiting the Americas. Geographical distribution is broadly discussed in the light of biogeographical and evolutionary origins. As a broad generalization, crocodilians are morphologically, genetically, and ecologically conservative and show a high dispersal ability, which together complicate the delimitation of species boundaries. Furthermore, distinct clades of crocodilians are a result of environmental selection for different adaptive characteristics. Gene flow occurs between clades, but distinct morphological varieties are sometimes a result of environmental filters. Thus, many taxa of crocodilians can be considered ecological species. Reproductive characteristics, such as nest-site choice and female reproductive output, influence reproductive success and thus population trends, so we discuss reproductive and habitat characteristics in the light of conservation genetics. Finally, the status of crocodilians is discussed both in terms of past hunting pressure and current conservation and management initiatives. In general, crocodilians can look after themselves if they have sufficient habitat, but some species are critically endangered by hunting, even though much of their original habitat remains intact. Conservation actions must be applied locally, taking into account threats and dispersal between source and sink populations. Given the difficulty of studying the dispersal of crocodilians by direct observation in most places in Latin America, the definition of effective management units will depend on genetic studies that can be linked to economic or conservation goals.