Mortality of Eggs of the Crocodile Crocodylus porosus in Northern Australia

Abstract

Most mortality of eggs of Crocodylus porosus in northern Australia is caused by flooding. Floods are of two types, short-term caused by the interaction of rainfall and tidal move- ments, and long-term caused by heavy rain. The duration of inundation necessary to kill eggs in laboratory experiments is longer than that normally experienced during tidal flooding, but less than that experienced during long-term flooding. Nests beside rivers are more likely to be flooded than those in swamps. Predation by varanids and humans causes fewer losses but this is probably because eggs are killed by floods in most years before predators have a chance to take them. The presence of an adult crocodile at the nest appears to deter varanids. Aboriginal hunters apparently are less efficient at finding nests in swamps than nests along rivers.