Johnston’s crocodile Traits, Behavior, and Conservation

Exploring the Unique Characteristics of Australia’s Freshwater Crocodile

The Australian Freshwater Crocodile (Crocodylus johnstoni), often referred to as the “freshie,” is a distinct species with unique traits that set it apart from its more notorious relative, the saltwater crocodile. The freshwater crocodile has a unique set of characteristics and behaviors that make it an intriguing subject of study.

These reptiles boast robust limbs, clawed webbed feet, and mighty tails. They are equally adept on land and in water, managing to zip along at speeds reaching up to 18 miles per hour.

The crocodile’s exterior is a blend of grey or olive-brown hues, complemented by a lighter belly, and adorned with darker mottling or bands stretching across the upper body, tail, and occasionally the snout. It features a sleek, narrow snout that tapers off, and its mouth is equipped with an impressive array of 68 to 72 razor-sharp teeth. Notably, the fourth tooth on either side of the lower jaw juts outward, remaining visible even when the creature’s mouth is shut.

During the dry season, female crocodiles lay approximately 20 eggs in sandy depressions, vigilantly guarding them until they hatch. Remarkably, the hatchlings begin calling from within their eggs before emerging. In response, the mother crocodile diligently digs up the nest, gently picks up the eggs in her mouth, and transports them to the water where they finally hatch.

 Juvenile crocodiles face a myriad of predators. Among the more formidable foes are adult crocodiles themselves, alongside hawks, turtles and sizable fish, all of which have been known to feast upon these young reptiles.

The nests of crocodiles are not spared from the attentions of predators either. Monitor lizards, dingoes, and even feral pigs are notorious for raiding these nests, seeking the eggs within.

It’s a harsh existence in the wild, where survival hinges on their ability to avoid so many threats.

Top freshwater crocodile facts

• Freshwater crocodiles can live for more than 50 years, showcasing a considerable lifespan that allows them to be key players in their ecosystems over many decades.
• Compared to their saltwater counterparts, freshwater crocodiles are smaller, generally growing to lengths of 2.5–3.5 meters. This more modest size influences their behavior, prey choices, and habitats.
• These crocodiles breed during the dry season (August–September). Females lay their eggs in holes they dig in sandy riverbanks, a strategy that protects the eggs from flooding and predation during the less rainy months.
• Unlike saltwater crocodiles, freshwater crocodiles are usually timid and avoid humans. However, they will defend themselves if threatened or cornered, though attacks on humans are rare and usually not fatal.
• Their diet is less diverse than that of saltwater crocodiles, primarily consisting of fish, crustaceans, insects, frogs, snakes, and small waterbirds. This diet reflects their adaptation to their specific freshwater environments.
• Freshwater crocodiles are found across northern Australia and are endemic to this region. They inhabit freshwater rivers, streams, and billabongs, preferring clearer waters where they can hunt their prey more effectively.
• Being endemic to northern Australia, the conservation of freshwater crocodiles is needed for maintaining the biodiversity and ecological balance of their natural habitats. They face different challenges compared to saltwater crocodiles, primarily from habitat loss and water pollution.

Freshwater Crocs in Australia

Freshwater crocodiles are found in the northern regions of the country, primarily inhabiting areas in Western Australia, Queensland, and the Northern Territory. These adaptable reptiles can be found in a variety of freshwater habitats, including rivers, creeks, lakes, and billabongs. Interestingly, they can also tolerate some level of salinity, allowing them to coexist with saltwater crocodiles in certain areas.

The difference between saltwater crocodile and freshwater crocodile

While both species are crocodiles, there are several key differences between saltwater and freshwater crocodiles:

1. Size – Freshwater crocodiles are significantly smaller, typically reaching lengths of 2-3 meters, while saltwater crocodiles can grow up to 6-7 meters.
2. Snout shape – Freshwater crocodiles have a longer, narrower snout compared to the broader, more powerful jaws of saltwater crocodiles.
3. Temperament – Freshwater crocodiles are generally considered less aggressive towards humans, although they can still bite if provoked.
4. Habitat preference – As their name suggests, freshwater crocodiles prefer freshwater environments, while saltwater crocodiles can thrive in both fresh and saltwater habitats.
5. Diet – Freshwater crocodiles typically feed on smaller prey, while saltwater crocodiles are capable of taking down larger animals.

Do freshwater crocodiles eat meat?

Yes, freshwater crocodiles are carnivorous and do eat meat. Their diet consists of a variety of prey, including:

1. Fish – A primary food source for freshwater crocodiles.
2. Insects – They often consume various aquatic and terrestrial insects.
3. Crustaceans – Crabs and shrimp are part of their diet.
4. Small mammals – They may occasionally prey on rodents or small marsupials.
5. Birds – Waterbirds can fall victim to these crocodiles.
6. Reptiles – Other small reptiles, including snakes and lizards, are sometimes consumed.

Freshwater crocodiles have adapted to catch smaller prey compared to their saltwater counterparts. They often use a “sit-and-wait” strategy, remaining motionless in shallow water before quickly snapping up passing prey with their narrow jaws.

Is it safe to swim with freshwater crocodiles?

Swimming with freshwater crocodiles is safer than swimming with saltwater crocodiles, but it’s not without risks.

• Freshwater crocodiles are not known to view humans as prey and are generally less aggressive than saltwater crocodiles.
• While rare, freshwater crocodiles may bite in self-defense if they feel threatened or are accidentally touched.
• There have been instances of freshwater crocodiles briefly attacking humans, likely mistaking a limb for their usual prey.
• In some areas, swimming with freshwater crocodiles is permitted and even promoted as a tourist activity. However follow local guidelines and warnings.
• If swimming in areas known to have freshwater crocodiles, it’s advisable to stay alert, avoid sudden movements, and keep a safe distance from the animals.
• If you choose to swim with freshwater crocodiles, it’s best to do so under the guidance of experienced local tour operators who understand the animals’ behavior.

Conservation Status and Threats

Despite their adaptability, freshwater crocodiles face several challenges:

1. Cane Toads – The introduction of poisonous cane toads has significantly impacted freshwater crocodile populations, as the crocodiles often die after ingesting these toxic amphibians.
2. Habitat Loss – Human development and alteration of waterways can affect their natural habitats.
3. Competition – In some areas, they face competition from the larger and more aggressive saltwater crocodiles.
4. Climate Change – Altering weather patterns and water availability could impact their breeding and survival rates.

The freshwater crocodile is an important species that plays a role in Australia’s freshwater ecosystems. While they may not be as well-known or feared as their saltwater relatives, these “freshies” are fascinating creatures in their own right.

As with all wildlife, it’s important to respect their space and natural behaviors. Whether you’re a wildlife enthusiast, a concerned citizen, or simply curious about Australia’s unique fauna, understanding and appreciating the freshwater crocodile contributes to the broader goal of conservation and coexistence with these ancient reptiles.