Salt Water Crocodiles

The Saltwater Crocodile is a far more formidable animal than its freshwater relative, and it does eat people.While normally found in estuaries and tidal rivers, these crocodiles also inhabit fresh water and will go out to sea. The smaller Saltwater Crocodiles feed on insects, frogs, small fish and  reptiles.The larger ones will eat fish, birds, reptiles and whatever other suitably sized animals they can get, including wallabies.

In the wet season females construct a nest of vegetation and soil and lay their eggs within. The eggs are left to incubate in the heat generated by the rotting vegetation. Mortality of eggs in nests is high,often because flooding covers the eggs with water and the embryos drown.

The females remain near their nests and will defend them from intruders It has been estimated that about 20 per cent of the eggs laid in a season actually hatch, and less than 1 per cent will reach maturity. As with Freshwater Crocodiles, the female will remove hatchlings from the nest and take them to the water.

Freshwater Crocodiles

The Freshwater Crocodile is smaller than the Saltwater Crocodile and has a narrow snout. It feeds on such prey as frogs, shrimps, fish and insects but will take anything of a suitable size. It is not regarded as dangerous to swimmers, although a close eye would be need to watch over children. Freshwater Crocodiles will bite if harassed.

Found only in northern Australia, the Freshwater Crocodile inhabits permanent freshwater swamps, billabongs and rivers. it may also move into the tidal areas of some rivers where the Saltwater Crocodiles are absent or low in numbers.

Nesting and Growth

During the dry season a female crocodile digs out a nest on a sandbank, lays her eggs and covers it over with sand. Several females may use the same area to nest, so sometimes a nest of eggs will be excavated by another female as she digs her own nest.

When they are born, the young call from the nest and are dug out by an adult female, who till carry them to the water in her mouth. Females will remain with groups of hatchlings for several weeks to protect them from predictors. During this period the mothers can be very aggressive.

In the upper reaches of the Liverpool River in Arnhem Land in the Northern Territory, the Freshwater Crocodiles exhibit extremely stunted growth. This seems to be related to their habitat which is somewhat rocky and lacking in food. Although they are mature the crocodiles here are considerably smaller in both size and weight compared to those found on coastal plains where food is more plentiful.