Our Venomous Neighbours - Brown Snakes
If you’ve been following the Our Venomous Neighbours series so far, you might have thought that by week three we’d be taking a leisurely dip into the world of honey bees. And until a few days ago you’d have been right. Instead, with the discovery of 19 eastern brown snake hatchlings in a Canberra home, we thought that now would be a good time to take a cold plunge into the depths of one of Australia’s deadliest snakes. So sit back and feel relieved by the fact that it’s very unlikely there are any baby brown snakes currently in your house as we introduce you to your venomous neighbour, the brown snake.
If you live in Australia, you’ve no doubt heard about brown snakes. These fast-moving and highly venomous snakes are responsible for more venomous bites and deaths than any other group of snakes in Australia. This sounds terrifying, but in context the rarity of snakebite deaths in Australia means that brown snake bites only result in 1-2 deaths per year. That’s about the same number of deaths that are caused by bee and wasp stings each year.
Nothing says don’t come any closer than the hallmark S-shaped defensive posture of this eastern brown snake (Pseudonaja textilis). Image: Scott Eipper. CC 2.
Brown snakes grow to average lengths of between 0.5 and 2.0m long, depending on the species, and belong to the genus Pseudonaja, which means ‘false cobra’. This moniker is a reference to their impressive defensive displays where they lift their head off the ground and contort themselves into an “S-shape” ready to strike. Like a terrifying episode of playschool brought to you by the letter Ssssss.
From coast to coast
In addition to that one particular house in Canberra, brown snakes are found all across mainland Australia, though you won’t find any in the wild in Tasmania. Before you start packing your bags to move across the Tasman, know that you’ll still have to keep an eye out for tiger snakes, lowland copperheads and whitelipped snakes when you get there.
A Gwardar or western brown snake. Image: Stephen Zozoya.
There are nine species of brown snake scattered across the country. Those of us in the eastern states are probably most familiar with the aptly named eastern or common brown snake (Pseudonaja textilis). If you live out west, you may be more familiar with the equally creatively named western brown snake or Gwardar (Pseudonaja mengdeni),while those of you in Perth and the south-western parts of Australia may be most aware of the dugite (Pseudonaja affinis). These three brown snake species are the most likely culprits when it comes to venomous bites by browns, but the list doesn’t stop there. There’s the speckled brown snake (Pseudonaja guttata) which has a speckled appearance, the ringed brown snake (Pseudonaja modesta) which often has a ringed appearance, and the strap-snouted brown snake (Pseudonaja aspidorhyncha) which has a distinctive chisel-shaped snout. Then there’s the northern brown snake (Pseudonaja nuchalis) which is found in the north and the peninsula brown snake (Pseudonaja inframacula) which oddly enough is found lurking around the Eyre and Yorke Peninsulas. It’s at this point that the creativity of the scientific naming process reaches its limit and we round out our brown snake list with Ingram’s brown snake (Pseudonaja ingrami), named after Collingwood Ingram - a Brit who studied birds.
Not all brown snakes are brown snakes
But wait a minute, what about the king brown snake? Well as it turns out, although the king brown, or mulga snake, is certainly a brown coloured snake, it’s not a brown snake from a scientific standpoint. It’s actually a black snake, scientifically speaking.
The king brown or Mulga snake is a brown snake that’s scientifically speaking a black snake. Image: Scott Eipper . CC 2.
Just as some brown snakes aren’t classified scientifically as brown snakes, some scientifically classified brown snakes aren’t brown snakes. In fact, snakes within the Pseudonaja genus come in a range of colours and patterns, even within the same species. Just take a look at how much variability there is in Gwardar / western brown snakes.
The many colours of the Gwardar or western brown snake. Image: Brian Bush.
These colour differences can also occur in individual snakes as they age. Juvenile eastern brown snakes often have dark rings on their bodies and characteristic black banding on their heads (see for yourself here), which both fade as they age. The dark ringed bands seen on young ringed brown snakes also grow faint as the snake grows bigger and older, much like the memories of that emo phase you went through in high school.
The characteristic dark rings of the ringed brown snake often fade as the snake grows. Images: Stephen Zozaya.
With brown snakes coming in such a wide range of, well, mainly brown... snakes, using colour alone isn’t really sufficient to correctly identify what type of snake you may be looking at. As a result, researchers and snake experts, known as herpetologists, use other distinguishing features including scale textures, numbers, and layout, head and eye shape, and general size and appearance to accurately identify snakes. This often requires getting up close and personal with the snake and is best left to the experts.
From the paddock to the plate
When it comes to deciding where to live, brown snakes are highly adaptable. As a result, you can find brown snakes in most habitats across the country, though they tend to avoid rainforests for the most part, which is fair as they’re not for everyone. If given the choice these snakes do have a slight preference for the more open and drier regions of the country. So don’t be surprised if you find them wandering around farms or homes in rural Australia looking for their next meal.
An eastern brown snake makes a meal of an unlucky bearded dragon. Image: Michael Dignand. CC 2.
When it comes to food, brown snakes are like people. They’re fussy when they’re young, but will eat pretty much anything as they grow. Young brown snakes specialise in hunting and eating lizards. Adult brown snakes eat lizards too, but they’ll also mix things up by eating birds, frogs and even other snakes. Though it’s fair to say that their meal of choice is small mammals such as mice and rats. You could think of mice as their version of pizza. Their love of rodents is thought to be why brown snake numbers have increased in recent years, particularly in rural areas. As we build more homes in rural areas we also provide the food and shelter to bring more mice and rats into the area. And they in turn attract the snakes.
Going through venomous changes
The diet of brown snakes is also thought to be at least partially responsible for the difference in venom that was recently found between young brown snakes and their older counterparts. This study, featuring AVRU’s own Dr Timothy Jackson, found that the venom of younger brown snakes acts on the nervous system, which would be very effective against lizards, while the venom of adult brown snakes acts to coagulate or thicken blood, which would stop a mouse in its tracks.
Brown snake venoms are some of the most potent venoms in the world. Like mice, the main toxins that affect us humans are the ones that target our blood. In brown snakes, these toxins are known as pro-coagulants as they promote the coagulation or clotting of blood. Adding these toxins to blood is similar to the effect of adding jelly crystals to water, eventually the liquid will become jelly. Though it’s fair to say that one jelly is much tastier than the other.
The best offense is a good defense
Despite their fiery reputation, brown snakes only tend to bite defensively. Though given we don’t often know they’re around, we won’t often know when they’re feeling threatened.Eastern brown snakes put on a good show, but they’d rather find a quick exit than go on the attack. Image: David Williams.
If you see a brown snake, remain calm and back away to safety. Remember that though we’re scared of them, we’re also much bigger than they are and so we don’t want to make sudden movements as this may make the snake jumpier than it needs to be. They’re not interested in fighting if they don’t have to and will try and make a quick exit where possible.
If the snake’s in your yard, get inside with any family and pets that are with you, keep an eye on it from a safe distance and call a snake catcher. If it’s inside the house, close the door to the room it’s in and use a towel or something similar to block the bottom of the door. And again call a snake catcher.
If you’re out bush walking, you can decrease your risk of brown snake bites by wearing sturdy footwear and long pants made of denim or other coarse fabrics which are difficult for the brown snakes’ short fangs to penetrate. These simple measures, while not foolproof, offer a considerable degree of protection.
In case of emergency
Brown snake bites are frequently painless and don’t necessarily result in a visible wound so any contact between the head of a brown snake and bare skin should be considered an emergency. If this happens or if someone you are with is bitten by a snake, keep them calm, move them away from the snake and call an ambulance immediately.
Remove jewellery (watches, rings, bracelets) and apply a firm compression bandage starting at the fingers or toes and moving up the limb to the upper arm or thigh. Apply the bandage over whatever clothes they’re wearing to avoid the unnecessary movement of taking them off. Use a piece of wood or something similar to splint the leg and restrict unnecessary movement. And if you can mark the bite site with a texta. This first aid technique is known as the pressure immobilisation and more information can be found here.
It’s important that the person who has been bitten stays as still and as calm as possible. This helps to keep the heart rate down and lessen the spread of the venom. Keeping the limb below the heart, simply by not elevating the limb, will also help. It’s also best to avoid washing the bite site as the venom on the skin can be used to help identify the snake.
Being bitten by a snake is a terrifying thought, but thankfully in Australia we have access to some of the best antivenoms in the world. For brown snakes, the recommended treatment is aptly called Brown Snake Antivenom (BSAV), made by Seqirus. Knowing that there’s effective medicine at a hospital near you will hopefully go some way to helping you stay calm in the unlikely case that a bite occurs.
Dr Andrew Watt