From near extinction to more than 100,000 in the Northern Territory, one of the world’s deadliest predators on the planet has SNAPPED BACK!
The population increase of these fearsome beasts is the result of this apex predator changing its diet from Surf to Turf!
As their numbers increase these cold-blooded predators are not only stalking the coast but moving inland to prey on any terrestrial being that enters its watery domain and almost always winning the fight!
1. Why have crocodile numbers increased?
Over 50 years ago crocodiles were heavily hunted until their numbers became increasingly low. Those remaining fed predominately on marine prey.
As the crocodile population recovered, they moved back to their river and floodplains systems in the Northern Territory where Feral pigs are abundant. As these Saltwater crocodiles changed their diet from marine animals to mammals, scientists say this could be why their numbers have rapidly climbed in northern Australia.
Competition for food resources, together with the increased number of hoofed animals on the floodplains are likely to be the key drivers of this dietary shift to more plentiful land-dwelling animals and hence the increased population.
This dietary shift coincides with the exponential increase in the Northern Territory’s crocodile population in the past 50 years. The significance of increasing terrestrial prey availability is contributing to large carnivore population recovery.
2. What evidence is there of this dietary shift from marine to terrestrial?
Bone samples from crocodiles that were killed around the 1960s had been stored at the Museum and Art Gallery of the Northern Territory. These samples together with bone samples of present-day saltwater crocodiles have been compared.
Naturally occurring carbon and nitrogen isotopes can be extracted from the crocodile’s bones and other tissue. These isotopes are derived directly from the animal’s diet and can be compared.
The present-day crocodiles in the Northern Territory have significantly lower values of both Carbon-13 and Nitrogen-15 isotopes. This reflects a shift from marine food sources to terrestrial prey. The researchers have also discovered that crocodiles which eat more land-based species have a less diversified diet than their predecessors.
3. How have crocodiles adapted to hunting terrestrial animals?
As the crocodile-hunting era finished the crocodiles have had more freedom to roam and increase their exposure areas. This together with the reduction in estuarine prey and the increase in number of feral pigs in freshwater floodplains has enabled the crocodiles to adapt to hunting terrestrial animals.
The high nutritional value of feral pigs is contributing to the increase in the size of the crocodiles. Bigger crocodiles are far more able to hunt terrestrial animals than their predecessors and consequently control the feral pig population further. In the Northern Territory the biomass, that is size, and the number is averaging 388kg per kilometre. The decline in the proportion of crocodiles in the 1-3 metre size range and increase in proportion for crocodiles to 3-4 metre size range has been observed
4. Can crocodiles help to control feral pig numbers?
Feral pig numbers in freshwater floodplains have increased dramatically and are having a detrimental effect on the environment.
Crocodiles are eating what they encounter and if more terrestrial food is available including feral pigs, then this supports a crocodile population boom. Moreover, they are then helping control the feral pig numbers.
Another change is that at the same time these apex predators are increasing the flow of land-based nutrients into floodplain, river, and estuarine aquatic ecosystems.
5. Are urban areas seeing an increase in crocodile sightings?
In the Northern Territory, there has been an increase from 3,000 crocodile sightings 50 years ago to 100,000. Consequently, rangers are now used to seeing crocodiles on their patrols. Despite their name, saltwater crocodiles or “Salties” are not exclusively found in saltwater. They are commonly found in freshwater pools and rivers many kilometres inland.
Last year a crocodile nest with eggs was found less than 1km from the suburban fringe of Palmerston, a city of around 40,000 people only a 15-minute drive from Darwin. This discovery is a sign that the Top End’s migratory crocodiles are venturing into new places as the good crocodile breeding habits are getting saturated by the rapid increase of numbers.
6. Why are crocodile attacks increasing?
Crocodile attacks in Australia have increased in recent years. As urban cities in the Northern Territory expand, they are encroaching on crocodile habitats, particularly mangrove swamps.
The soaring crocodile sightings are showing more than a 38% increase with reports the crocodiles are expanding their territory into areas traditionally thought to be crocodile free.
Saltwater crocodile attacks normally result from the unnatural proximity of human communities to crocodiles. Wildlife experts are advising locals to take extra precautions during the breeding season and steer clear of their habitats.
Increased rainfall should bring caution as this causes a sharp rise in water levels in lakes, forcing animals from their natural habitat into drier conditions.
To minimise the risk of lives implementing a crocodile conservation program has been suggested to include relocating residents away from crocodile habitats, as the need for livelihood and residential spaces continues to raise risks to the ecology and lives of people.
Anglers have been warned to be warier as attacks against men in pursuit of their hobby puts them close to crocs when fishing.
7. Why have crocodiles driven to extinction 50 years ago?
Crocodiles are ancient reptiles with their ancestors around before the age of the dinosaurs. What makes them so long-lasting is that they are perfectly adapted to their environment. They simply only move if the prey is worth catching, in order to preserve energy.
Indigenous Australians had historically kept crocodile numbers in check by harvesting their eggs. A balance in numbers was also reached by them killing crocodiles for their meat.
However, fifty years ago crocodiles hunting for their skins pushed them to the brink of extinction. The availability of .303 rifles after World War 2 provided the calibre to kill crocodiles reliably, rather than the lighter rifles. The political unrest in Africa reduced the supply of crocodile skins increasing prices through a shortage of supply making crocodile hunting more lucrative.
Crocodile hunting was a dangerous pursuit and many ex-servicemen and women who were keen on an adventure and a trophy hunt enjoyed the sport. Crocodile hunting took off in a big way after 1945. As a result, there was a dramatic decline and the crocodile population teetered to a perilously low of 3,000.
In 1962, freshwater crocodiles were protected in WA and in 1970 protection was given to the saltwater crocodiles. In 1971 complete protection was given to crocodiles in the NT. In 1974 the Australian government put the species under federal protection
8. How can a crocodile see prey without moving his head?
From snout to tail these reptiles are built to ambush prey. Using their impressive strength and enormous size they can effectively take down prey as they are startled. Concealed by their armoured skin, which looks like bumpy rocks or logs adds an advantage, but it is the adaption of their eyes which give them an edge too.
Part of the retina called the foveae has tightly packed receptors that deliver sharp vision and, in the crocodile, it is a horizontal streak instead of the usual circular shape. The retina in the eye is elongated in this way for sharp central vision as they lurk at the water line. The visual horizon along the riverbank has increased visual clarity allowing the crocodile to see fine detail without moving their head.
Small prey is crushed by the predators’ powerful jaws and swallowed. Larger prey may be dragged to deeper water before being dismembered and eaten.
9. Do Crocodiles eat humans?
Given the opportunity, crocodiles can eat whatever prey they come across including humans! The most common crocodile attacks are on men, usually locals. They have been around crocodiles for a long time and have become careless. All it takes is for a person to be in the wrong place at the wrong time and you will be dinner for a croc!
Crocodiles are one of the most terrifying animals that live in water. The tail of a crocodile alone can break bone with one smooth swing and will easily knock a man off his feet. Hidden between their jaws are 60-80 long pointed teeth. Perfect for tearing, clenching, and grabbing and they are constantly replaceable. Their bite is 3 times more powerful than a lion which explains how dangerous these animals are and gives you a genuine reason to be afraid of them. In the Northern Territory’s waterways, big crocodiles are now abundant in places where people once swam without fear. The larger the crocodile the larger the prey!
Saltwater crocodiles are known to prey on people all through human evolution Their aggressive attacks can brutally wound a human body when they kill them as their prey.
Anytime you are near a creek, billabong, river the beach or other swimming holes in the northern part of Australia you should be aware that there is a chance of a crocodile living nearby. Due to the increase in crocodile numbers, crocodiles are being found further south every year, so everyone should always be on the lookout if near water.
As one of the oldest species to still walk the Earth. If you do see one you have the closest thing to staring down a carnivorous dinosaur!
10. Are crocodiles fast on land?
Even though crocodiles can swim up to a top speed of 20kph when travelling on their belly they can only reach a speed of about 12kph. They have been known to run as fast as 17kph and travel 20-30 metres in a sprint They cannot run for long distances as they quickly tire.
They can also make a reasonable attempt to climb fences, but they can lunge at much faster speeds making the crocodile lethal should the prey not make it away in time.
If a person was being chased by a crocodile, they would have a good chance of making it out unharmed but if ambushed in the water their chances of making it out are not as high.
