Living with Crocodiles

Family: Crocodylidae
Scientific names: Crocodylus porosus (Estuarine crocodile) Crocodylus johnstoni (Freshwater crocodile)

Crocodiles in the environment

Freshwater and estuarine (saltwater) crocodiles are found in the NT. Freshwater crocodiles, which are also referred to as ‘freshies’, can be found throughout inland river and lagoon systems across the Top End, including the Katherine, Victoria River and Mataranka regions. Contrary to what their name suggests, saltwater crocodiles (also known as estuarine crocodiles or more commonly ’salties’) are found across a wide range of habitats, including freshwater and saltwater environments. Estuarine crocodiles inhabit all Top End coastal waters, rivers and wetland systems and may be found in watercourses more then 300km inland.

Both species of crocodile rely on external heating (known as thermoregulation) and can often be seen basking out of the water in cooler weather.

Feeding

Crocodiles are carnivorous and feed on a wide range of animals, including fish, frogs, birds, mammals, crustaceans and reptiles (including other crocodiles). Freshwater crocodiles are restricted to smaller prey items due to their slender snout, such as fish and freshwater crustaceans. Estuarine crocodiles, on the other hand, utilise their bulky powerful snout and jaws to feed on just about any animal living in or entering the water, including wallabies, pigs, turtles, horses and occasionally humans.

Crocodiles are important predators and help maintain healthy ecosystems through population control of species such as wallabies, fish and waterbirds. Crocodiles are also known to prey on a range of introduced pest animals, including feral pigs and dogs.

Threats

In the early 1970s, saltwater crocodiles were on the brink of extinction, with broad scale unmanaged hunting occurring throughout the Top End. In 1971, crocodiles were awarded full protection under the Territory Parks and Wildlife Conservation Act which allowed for populations to recover. Today, the Northern Territory has the largest saltwater crocodile population in Australia. Researchers continue to monitor estuarine crocodile populations and permitted annual harvesting.

Recent reports suggest that freshwater crocodile populations may suffer with the spread of the cane toad which has enough poison to kill a small crocodile. Anecdotal evidence suggests that freshwater crocodiles will perish as a result of consuming a cane toad; however the impacts on their populations are largely unknown. In urban areas, crocodiles may also occasionally fall victim to boat strikes and accidental drowning in fishing nets due to their close proximity to humans.

Interactions with people

In areas occupied by humans, crocodiles take advantage of opportunistic food supplies, regular visitation by potential prey such as livestock and pets, and easy land access via boat ramps and crossings. The Parks and Wildlife Service actively manages problem crocodiles. Interactions between humans and crocodiles should be minimised were possible, particularly in areas known to support saltwater crocodiles.