Mulga

(Pseudechis australis)

The mulga snake (Pseudechis australis) is one of Australia’s largest and most widely distributed venomous snakes. Despite its name, the mulga, also known as the king brown snake, is actually a member of the black snake genus.

Other names

King brown snake or Pilbara cobra (nickname)

Description

This large and robust snake can reach a total length of 3.3 metres, although the average length is around 1.8 metres. Their colour varies geographically, ranging from red-brown, yellow-brown, olive-brown or brownish-black, and their scales commonly have a darker outer portion and a lighter base, creating a reticulated effect. Northern snakes can be relatively pale, while southern populations may be almost black.

Mulga snakes have a broad, round head and smooth scales. Their head colouring normally matches their body colouring and their belly is normally cream to salmon-coloured, sometimes with orange blotches. Their eyes are quite small, with a pale red-brown iris, and their cheeks are quite bulbous in appearance.

Juveniles of this species may not have a robust appearance like adults.

Important: Colour, markings and overall appearance can vary considerably between individual snakes. Photographs, descriptions and information on this website should not be relied upon to identify a potentially venomous snake. If you encounter a snake, keep your distance and leave identification and removal to trained professionals.

mulga-king-brown-pseudechis-australis-si

Mulga snake (Pseudechis australis). Photography: © Amanda Long

Identification

Midbody: 17 rows
Ventrals: 185-225
Subcaudals: 50-80, anterior single and posterior divided, occasionally all single
Anal: divided
Supralabials: 6
Temporolabial present

Distribution

With the highest distribution of any Australian snake, the mulga can be found throughout Australia, apart from southern and eastern coastlines. Their distribution extends beyond Australia, with the species also inhabiting south-eastern Irian Jaya and possibly western Papua New Guinea.

Habitat

Depending on its location, the mulga snake may be found in environments including monsoon forest, woodlands, shrublands, sandy deserts, and wheat fields. The variety of colours these snakes display helps them blend into their natural environment, keeping them safe and allowing them to ambush prey effectively. They often shelter in abandoned animal burrows, deep soil cracks, rock cavities, hollow logs, and under fallen timber and large rocks.

Diet

Mulgas typically hunt in the early morning and late afternoon, searching for other reptiles, reptile eggs, birds and small mammals. When food is scarce, they have been known to also consume invertebrates and carrion. Mulgas appear to be immune to the venom of the western brown snake (Pseudonaja nuchalis) and will sometimes consume them, with no ill-effects occurring if their meal bites back.

Reproduction

Combat behaviour has been observed in males of this species, with males entwining their bodies and using their heads to try to push each other over. Mating season commences from early to mid-spring, depending on location. Northern populations may differ, with mating coinciding with the wet and post-wet season. The species is oviparous. Approximately 39-42 days after mating, the female lays between 4 and 20 eggs, with an average clutch size of 9. The baby snakes take between 70 and 100 days to hatch, and incubation temperature influences the timeframe.

Venom

Mulga snake venom is highly toxic and produced in large quantities. Its effects on the human body can include:

Neurotoxic effects, affecting nerve cells and the nervous system
Haemolytic effects, causing the breakdown of blood cells
Cytotoxic effects, which can damage or disrupt cells
Myotoxic effects, which affect muscle tissue

While these effects can be dangerous to humans, snake venom is also a complex source of biologically active compounds. By studying how these components interact with the human body, scientists can better understand disease processes and explore their potential for developing new medicines and treatments. In this way, research into snake venom can help us turn something potentially harmful into knowledge that may ultimately benefit human health.

Predators

Fortunately for mulga snakes, they have few predators. Accidental poisoning from ingesting cane toads has impacted the species population, particularly in some northern areas. The species is also vulnerable to parasites, such as nematodes, with older specimens often being vulnerable to ticks. Small mulgas are also susceptible to birds of prey.

Conservation status

The IUCN Red List classifies the mulga snake as a species of least concern. The wide distribution of this snake throughout Australia reduces its vulnerability.

Fangtastic Fact

When threatened, the mulga snake spreads its neck and upper body into a flattened display, earning it the nickname “Pilbara Cobra” for its resemblance to a cobra’s classic threat posture. It may also emit a loud, forceful hiss to deter approach, and while holding its flattened stance, it often sways its head and neck from side to side in an intimidating motion. Although it will bite if it feels seriously threatened, these behaviours are primarily a means of protecting itself.

Disclaimer

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Content on this website is provided for general educational purposes and is not suitable for identifying snakes or guiding interactions with them. While reasonable care is taken to ensure accuracy, no guarantee is made regarding completeness or suitability for specific circumstances. Wild snakes should not be approached or handled, and professional snake catchers should be contacted if assistance is required. By using this website, users acknowledge and accept these terms.

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