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How can you tell if a brown snake is poisonous?

As a hiker, camper, or gardener, it’s important to be able to identify venomous snakes for your own safety. While most snakes will avoid humans if given the chance, it’s still good to know the warning signs of poisonous snakes in case you encounter one unexpectedly.

Brown snakes in particular can be dangerous, especially in Australia where they are found in abundance. Out of the 35 known species of brown snake, 12 of them are venomous. With varying shades of brown, tan, and grey, it can be tricky at first glance to know if a brown snake poses a risk.

Look at the head and neck shape

One of the best ways to identify a potentially dangerous brown snake is to look at the shape of its head and neck. Venomous snakes tend to have arrow-shaped heads and narrow necks compared to nonvenomous species.

This is because venomous snakes have enlarged venom glands at the back of their heads. The glands release venom through fangs which venomous snakes use to subdue their prey. This enlarged head and narrowed neck helps accommodate their venom delivery system.

So if you spot a brown snake with an arrow-shaped head and thin neck, that’s a sign it may be poisonous.

Watch out for vertical pupil slits

Another key identifier is the snake’s pupils. Venomous snakes typically have vertical slit-shaped pupils, like that of a cat’s eye. This helps them better sense and focus on movements of potential prey.

Nonvenomous snakes usually have round pupils. So if you can get close enough to see a brown snake’s eyes and they are vertically-oriented slits, consider that a warning sign.

Look for fangs

Many venomous snakes including brown snakes have enlarged fangs used to deliver their toxic venom. While nonvenomous snakes have small teeth, venomous ones have long hollow fangs. These are attached to poison glands and can be folded back when the snake’s mouth is closed.

If you spot any fang-like teeth protruding from a brown snake’s closed mouth, treat it with extreme caution as those fangs likely indicate it’s venomous.

Identify key body features

There are a few other body features that can help distinguish a venomous brown snake from a harmless one:

  • Size – Venomous brown snakes tend to be smaller, ranging from 2-5 feet long. Nonvenomous brown snakes get larger, typically 3-6 feet in length.
  • Tail – The tail of a venomous brown snake comes to a fine point. Nonvenomous brown snakes have a blunt tail tip.
  • Scales – Venomous varieties have smooth scales while nonvenomous brown snakes scales are more keeled (having a raised ridge down the center).

Taking note of these body features in combination with the head, eyes, and fangs can help positively identify a dangerous brown snake.

Watch its behavior

Observing a brown snake’s behavior can also offer clues as to whether it’s venomous. Here are some behavioral warning signs:

  • Coiled posture – Venomous snakes may coil their bodies when threatened as preparation before striking.
  • Hissing or shaking tail – To warn away predators, venomous snakes may hiss loudly or vibrate their tails rapidly when aggravated.
  • Head positioned to strike – A venomous brown snake may pull its head back and rotate it slightly just before attacking, so it can strike accurately.
  • Quick retreat – If given the option, most venomous snakes will flee from humans and only strike as a last resort if they feel cornered or provoked.

Of course, not all snakes with these behaviors are dangerous, and some nonvenomous snake species may mimic these behaviors too. But being aware of a brown snake exhibiting them means you should treat it with maximum caution in case it is venomous.

Know the habitat

Knowing what kind of environment or habitat venomous brown snakes prefer can also help with identification. In Australia, these venomous species tend to thrive in the following areas:

  • Grasslands
  • Scrublands
  • Fields
  • Forests
  • Rocky outcrops

If you come across a brown snake in these habitats, the odds increase that it could be a dangerous variety. Exercise extreme care and try to retreat slowly to safety.


Being able to identify a venomous brown snake can ultimately save your life, or at least prevent a painful snake bite. While they may seem tricky to identify at first, looking for key physical features like arrow-shaped heads, vertical pupil slits, pointed tails, and smooth scales can help clue you in.

Observing the snake’s confrontational behaviors like coiling, hissing, and positioning to strike can also hint that a brown snake is likely venomous. Your safety is most assured if you simply give all brown snakes their space and do not try to touch or aggravate them in any way.

If possible, quietly retreat from the area and notify others nearby of the snake’s presence. Learning to be aware of your surroundings and identify signs of danger can help you appreciate nature safely!

Venomous Brown Snakes in Australia

Species Venom Toxicity (LD50)* Average Length Habitat
Eastern brown snake 0.0365 mg/kg Up to 7 feet Forests, farms
Western brown snake 0.006 mg/kg 3-5 feet Scrublands, dunes
Dugite 0.12 mg/kg 3-5 feet Scrublands, heaths
Gwardar 0.40 mg/kg 2-3 feet Grasslands, plains
Night tiger snake 0.225 mg/kg 2-3 feet Woodlands, farms

*LD50 is the estimated amount of venom per kg of body weight that would kill 50% of human victims