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Episode 365: Sizing up the Saltwater Crocodile

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The enormous saltwater crocodile (image from the BBC)

As if crocodiles couldn’t be any more intimidating, the saltwater crocodile is the largest reptile on earth, reaching impressive lengths of up to 6 meters and maxing the scales at 1500 kilograms. There are even historical reports of salties reaching around 6.2 meters, and skulls found indicate that they once reached frankly monstrous sizes of 7 meters! In the 20th century, many saltwater crocodiles were hunted for their skin, with the largest preferentially taken, so these huge sizes are no longer seen. These enormous reptiles can be found cruising throughout mangrove swamps, river deltas, estuaries and oceans in Eastern India, Southeast Asia and Australia. In the tropical wet season,  saltwater crocodiles will spend their time in swamps and rivers, and in the dry season they can be found in estuaries. Unlike other crocodile species, which are generally very social and share food and basking spots, saltwater crocodiles are very competitive over their territories, with dominant males snapping up (no pun intended) the best locations on river banks, pushing less dominant crocs to smaller river systems and into the oceans. 

They will prey on almost all animals, fish, crustaceans, mammals (and yes that includes humans!) reptiles, birds and even other large predators like sharks!

A living dinosaur: behavioural ecology of the saltwater crocodile

All crocodiles have the ability to enter saltwater, as they have salt glands to excrete salt when passing through marine waters, but only salties have the ability to spend significant time in the seas. Crocodiles fitted with GPS tags by researchers found that they will conserve energy by using ocean currents to travel as far as 590 kilometers in 25 days. They will often shelter in bays until the currents change in the direction they want to go. They can spend weeks at sea searching for land, and have even been spotted with barnacles growing on them! Salties are pretty good at conserving energy when they need to, and will spend long hours basking in the sun. These strategies allow them to go months without food. 

A typical basking location of a saltwater crocodile (image from phys.org)

When they are finally hungry however, they are incredibly efficient and dangerous predators, agile and able to move quickly when needed. Although many people think of them as primitive, practically prehistoric animals, salties display incredible intelligence, able to learn complex tasks with minimal conditioning. Scientists suspect they have far more advanced communication than thought, and are even capable of tracking the migration routes of prey animals around river and estuary systems. 

They hunting methods are no different than other crocodile species; they will submerge themselves in the water and swim quietly up to their prey, then strike quickly upwards. 

Never smile at a crocodile: how dangerous are salties? 

Saltwater crocodiles are incredibly aggressive and territorial, and this, coupled with their enormous size, makes them incredibly hard to study. Researchers use huge poles and hooks usually reserved for sharks that can restrict their jaws, but even this heavy duty equipment is not enough to restrict crocs over 4 meters. Any crocs of that size simply get observed from a safe difference!

Along with Nile crocodiles, salties are some of the most dangerous predators to man. A direct predatory attack from a saltie is pretty much non survivable. Unlike alligators, with whom people can co-exist to some extent, the best way to live alongside saltwater crocodiles is to completely avoid them; they are far too large and aggressive! 

A typical sign indicating the presence of saltwater crocs in the region

In Australia, despite the prevalence of salties, attacks are fortunately relatively rare. Between 1971 and 2016, 106 deaths from crocodile attacks have been recorded. This is largely down to the hard work of wildlife officials, who work to preserve saltwater crocodile habitat and keep people away with hazard signs and educating locals of the danger. It is entirely possible however that there are more, less publicized attacks in other poorer, more rural parts of the world, where people can’t avoid the crocodiles as they rely on their habitat for food or washing. In some areas, some people claim there are thousands of attacks, although there is some suspicion this is wildly overexaggerated and may stem from leather companies keen to scare people and reduce any protests against crocodile hunting for their skins. In reality, despite their aggressive nature, like most animals, salties are very wary in most cases. Attacks that do occur are very often territorial in nature rather than predatory; for example, they frequently attack boats as they view them as a threat. Most fatal attacks are usually caused by crocodiles over 4 meters. They have a fearsome reputation, but there is some evidence that their smaller relative, the Nile crocodile is behind more attacks. However, rather than levels of aggression, this may be due to the fact that many poor rural communities in Africa rely on rivers for their livelihood, bringing them into regular contact with crocodiles inhabiting the same waterways.

Scary but important: the conservation status of the Saltwater Crocodile

Fortunately, these fearsome aquatic predators are currently listed as least concern by the IUCN red list. They are also protected under the CITES act 1 and 2, preventing all commercial trade in live animals or animal parts except in certain parts of Australia and Papua New Guinea. 

During the 20th century, saltwater crocodiles were subject to intensive unregulated hunting for their meat, eggs and skins. By 1971, their numbers had fallen by a staggering 95%, and in 1974, they were placed under full legal protection in all Australian states. Despite this, the legal protection is not entirely effective in all places, including Australia but especially countries such as Sri Lanka, where it is now incredibly rare to see any large males. 

Habitat loss is also a significant problem, as their rivers and estuaries become degraded and reduced. Many nesting areas are being destroyed to make way for agricultural developments, especially in regions like the Andaman Islands. Unfortunately, with their prehistoric looks and fearsome reputation, it is very difficult to drum up support for crocodile conservation. 

Fortunately though, many people do care about crocodiles, and one organization spearheading saltwater crocodile conservation is Steve Irwin’s Australia Zoo. This should come as no surprise, given Steve Irwins’ love and passion for reptiles. The Zoo manages several large research projects and are a huge force driving a change in the way people view reptiles. They will also monitor the movements and behavior of saltwater crocodiles with GPS tags (and a team of brave scientists who will get close enough to attach them!). This helps to understand how salties use their environment and how to reduce potential human wildlife conflict. To learn more about their work with salties, visit Petition – Stop the Harvesting of Crocodile Eggs (australiazoo.com.au)

Awesome videos!


Amarasinghe, A.T. Madawala, M.B. Karunarathna, D.S. Manolis, S.C. de Silva, A. Sommerland, R. (2015) ‘Human-crocodile conflict and conservation implications of saltwater crocodiles in Sri Lanka.’ Journal of Threatened Taxa

Caldicott, D.G.E. Croser, D. Manolis, C. Webb, G. Britton, A. (2005) ‘Crocodile attack in Australia: an analysis of its incidence and review of the pathology and management of crocodilian attacks in general.’ Wilderness and Environmental Medicine

Campbell, H.A. Dwyer, R.G. Irwin, T.R. Franklin, C.E. (2013) ‘Home range utilization and long range movement of estuarine crocodiles during the breeding and nesting season.’ PLOS ONE

Campbell, H.A. Watts, M.E. Sullivan, S. Read, M.A. Choukron, S. Irwin, S.R. Franklin, C.E. (2010) ‘Estuarine crocodiles ride surface currents to facilitate long-distance travel.; Journal of Animal Ecology

Crocodylus porosus (Saltwater Crocodile) (iucnredlist.org)

Das, C.S. Jana, R. (2018) ‘Human-crocodile conflict in the Indian Sundarban: an analysis of spatio-temporal incidences in relation to people’s livelihood.’ Oryx

Doody, J.S. (2009) ‘Eyes bigger than stomach: prey catching and retrieval in the saltwater crocodile.’ Herpetological Review 

Evans, L. Jones, T. Pang, K. Saimin, S. Goossens, B. (2016) ‘Spatial ecology of estuarine crocodile nesting in a fragmented landscape.’ Sensors

Kar, S.K. Bustard, H.R. (1983) ‘Saltwater crocodile attacks on man.’ Biological Conservation

Kay, W.R. (2005) ‘Movements and home ranges of radio tracked Crocodylus porosus in the Cambridge Gulf Region of Western Australia.’ Wildlife Research

Lang, J.W. (1987) ‘Crocodilian behaviour: implications for management.’ Wildlife management: crocodiles and alligators

Leach, G. Delaney, R. and Fukuda, Y. (2009) ‘Management program for the saltwater crocodile in the Northern Territory of Australia, 2009-2014. Department of Natural Resources

Nayak, L. Sharma, S.D. Priyadarshini, P.M. (2018) ‘Conservation and Management of Saltwater Crocodile in Bhitarkanika Wildlife Sanctuary, Odisha, India.’ Environmental Management of Marine Ecosystems

Read, M.A. Grigg, G.C. Irwin, S.R. Shanahan, D. Franklin, C.E. (2007) ‘Satellite tracking reveals long distance coastal travel and homing by translocated estuarine crocodiles.’ PLOS ONE

Spennemann, D.H.R. (2021) ‘Cruising the currents: observations of extra limital Saltwater Crocodiles in the Pacific Region.’ Pacific Science 

Tisdell, C. Nantha, H.S. Wilson, C. (2007) ‘Endangerment and likeability of wildlife species: how important are they for payments proposed for conservation?’ Ecological Economics

Webb, G.J.W. Messel, H. (1979) ‘Wariness in Crocodylus porosus.’ Wildlife Research


December 06, 2023
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