Estuarine crocodiles are distributed throughout the coastal regions of northern Australia, from Broome in Western Australia to Rockhampton in Queensland.
It is found primarily in mangrove-lined tidal rivers up to 200 km from the coast, in creeks and freshwater swamps up to 100 km from the coast.
Adults have even been found swimming 1000 km out to sea.
Estuarine crocodiles can be found basking on the exposed mud of tidal riverbanks during cooler months, but in the summer spend their time in the water and shade coming out to hunt at night.
Saltwater crocodiles are found in higher densities where there are good nesting sites and lots of food.
Hatchlings are born with very sharp teeth and will begin feeding almost immediately. Juveniles will take a wide variety of small prey such as insects, shellfish and small fish. Adult saltwater crocodiles will take dingos, wallabies, shore birds, other crocodiles, large reptiles, domestic animals, cattle and even people.
Their teeth are designed for holding rather than cutting and they help to crush the prey with their incredibly powerful jaws. Large prey is broken into small pieces by a violent flick of the head, or a twisting/rolling action of the body.
Swallowing must occur above the water surface, or water will flood the lungs.
The estuarine crocodile will wait close to the water’s edge and pounce upon prey which ventures too close.
Estuarine crocodiles lay between 40 and 60 eggs depending on the size and age of the female. The eggs weight around 113 grams and measure 80 mm x 50 mm. Estuarine crocodile hatchlings weigh around 72 grams and measure 29 cm in length.
The biggest estuarine crocodile ever documented was 7 metres long, and over 1000 kg in weight. The average size is 5 to 6 metres.
Males live to at least 70 years and possible even 100 years old.
Growth generally continues throughout life, but is much slower in older animals.
Large crocodiles can be aged by the number of growth rings in their bones.
Unregulated hunting up the 1970s brought the estuarine population to the brink of collapse. But in 1971 (and 1974 in Queensland) saltwater crocodiles have been protected allowing the population to show an excellent recovery rate.
Most attacks by crocodiles occur in the wet season, when they do most of their feeding and growing. In general crocodiles do not attack fishing boats and there have been 14 deaths caused by crocodiles throughout Australia in the last 27 years.Read More: Spiny Anteater