Reptiles - Crocodiles

Although the Estuarine Crocodile (Crocodylus porosus) is not confined to the Wet Tropics, it is by far the best known reptile of Tropical North Queensland. For an animal of such power and ability to exist over tens of millions of years, the crocodile is almost defenceless against the power that human fear creates.

There have been occasional attacks on people in developed and remote areas of Tropical North Queensland and these receive more than ample publicity. However, in many cases, such traumatic events have been the result of less than careful judgement. Cleaning fish on the edge of a river or near a boat ramp is to a crocodile what 'chumming' is to a shark. (Chum is a slaughterhouse concoction poured off the side of a boat to attract sharks.) Going for a midnight swim in an estuary is just as much a gamble as picking up a cobra and wrapping it around your neck! But such accidents have happened and these have a great impact on people's fear and hatred of the crocodile - an animal which deserves a healthy respect.

The estuarine crocodile is an ancient species and one which can live a long time - up to 100 years - but many of the oldest and largest crocs were hunted out by the 1970's. Crocodiles up to 8.4 metres (28 feet) long have been verified in the past but nowadays, most crocs only reach about 5 metres. They are fully protected (including their eggs) and regulated crocodile farms provide controlled products (meat and skins) for domestic and international trade.

 
Crocodiles have some very interesting capabilities:

• they can hold their breath underwater for up to one and a half hours
• they have a lingual gland at the back of the throat that removes salt from their body
• their brain is only the size of a walnut but it still allows enough 'processing' to take place to enable the animal to make a decision about whether to attack or not
• crocs replace their teeth by growing new ones inside old ones which eventually fall out
• the stomach of the crocodile is only about the size of a basketball and contrary to legends and 'old wives' tales', crocs do not store their food - they eat it right away
• of 23 species of crocodiles worldwide, ours is considered the most aggressive
  

While this powerful animal can easily tear a large animal apart, it also exhibits the gentlest behaviour with its offspring. The croc builds a mound to incubate its eggs (like the megapodes, the Scrub fowl and the Brush Turkey) and when its 50 or so eggs have hatched and the young have climbed to the surface, the female picks them up in her mouth and carries them carefully down to the water. Males can be predators of their own young but females are very protective and stay close to the mound during the three months the eggs are incubating (November to March).

The best and safest place to see crocodiles might be at a fauna park. There are river tours which feature the estuarine crocodile as a draw card, but it is dependent on the time of year as to whether wild crocodiles can be seen. The wet season temperatures are usually too hot so the crocodiles submerge to the river bottom during the day. However, in the cooler winter months, crocs bask on the banks of some rivers. After decades of hunting, however, many crocs have become wary of the sound of boat motors so even the winter visitor might only see the tell-tale "slide" on the bank instead of the animal (slides are the tail and footprint impression left on the muddy bank after a crocodile has darted into the water).

In Cairns, a crocodile removal program is in progress for all areas except the mangrove wetland system adjacent to Trinity Inlet (Cairns harbour). All Estuarine crocodiles are trapped and relocated to remote areas. While this trial program reduces the likelihood of a human-croc encounter in the Cairns area, it also involves a research component so that we can learn more about the crocodile's ecology and survival rates once moved.