The role of predation in shaping crocodilian natural history

Although adult crocodilians have few predators (mostly humans and other crocodilians), hatchlings and eggs are killed and consumed by a diverse array of invertebrates, fishes, anurans, reptiles, birds, and mammals. We review published literature to evaluate the incidence of predation in crocodilian populations, and the implications of that mortality for crocodilian life-history evolution. Presumably because predation is size-dependent, small-bodied crocodilian taxa appear to be more vulnerable to predation (across a range of life stages) than are larger-bodied species. Several features of crocodilian biology likely reflect adaptations to reducing vulnerability to predation. For example, the threat of predation may have influenced the evolution of traits such as nest-site selection, maternal care of eggs and hatchlings, crèche behavior in hatchlings, and cryptic coloration and patterning. Even for such large and superficially invulnerable taxa such as crocodilians, the avoidance of predation appears to have been a significant selective force on behavior, morphology, and ecology.