Citizen science is ripe with benefits. Programs can involve hundreds, sometimes thousands, of volunteers who collect reliable, long-term and geographically widespread data. These people donate their time for a cause (or just for fun).
For biodiversity conservation, these kinds of data are invaluable to enable important large-scale projects, from assessing wildlife recovery after bushfires to shedding light on how warming oceans threaten fish.
But we’ve found the benefits of citizen science extend well beyond data collection.
In a new research paper, we show how our environmental citizen science program TurtleSAT
is not only an important source of knowledge and skill development, but also influences participants’ attitudes and behaviours towards the environment.
TurtleSAT has so far engaged more than 1,600 volunteers who collect observations of freshwater turtles. Almost 10,000 sightings have been registered since it launched in 2014. The data will ultimately help turtle conservation and management across the country.
Turtles live in most freshwater habitats across mainland Australia, from wetlands to rivers, and are a vital component of the ecosystem. For example, in previous research, we revealed turtle scavenging can remove fish carcasses from the water five times faster than natural decomposition, dramatically improving water quality.
But turtle numbers have been in steep decline since the 1970s, mainly due to fox predation, road collisions, diseases and poor water quality.
The benefits of the TurtleSAT app to scientists have been clear from the start. Most recorded turtle sightings (alive and dead) have involved turtles crossing roads and nests that are either intact or have been destroyed by foxes.
However, the benefits to participants were less clear. So, we surveyed them to gauge any changes in behaviour or attitudes since they got involved.
Of the 148 participants who responded, most (70%) said they’ve learned more about turtles and feel like they’re helping them by participating. After one of our school workshops, for example, a parent told us she didn’t know turtles could live outside the ocean until her daughter began participating in TurtleSAT.
After learning about the turtle population decline, 39% of respondents started restoring habitats, 35% protected nests and 30% implemented pest management mechanisms, such as fox control and predator exclusion fences.
Importantly, 70% of respondents said participating in the program made them more worried about turtles than they were before.
These findings show how a mostly self-directed project can provide benefits to citizen scientists, while also providing a platform for them to contribute to the conservation of animals they love.
Citizen science programs link the fields of science and the humanities to create an educated and informed public that knows how to solve problems and, most importantly, care enough to do so.
One reason many people aren’t motivated to address climate change and other global issues is the effects are relatively distant from their day-to-day living.
Most people aren’t forced to confront the specifics of climate change (such as extreme weather disasters) in their everyday lives, and so can treat it as an abstract concept. Simply put, this doesn’t motivate people to act.
Citizen science programs, however, can show how climate change does actually affect participants. They become equipped with the information and tools to make significant positive changes to their local area and, most importantly, see direct outcomes.
For example, when citizen scientists spot migratory birds in their neighbourhood, it can help researchers develop long-term databases to evaluate whether changes in migration timing can be attributed to average spring temperature changes.
Likewise, we’re monitoring the timing of turtle nesting with TurtleSAT, as many turtles in eastern Australia are cued to nest in late spring. Similar research found Loggerhead sea turtles were nesting earlier due to warmer ocean temperatures.
This knowledge wouldn’t have been possible without long-term citizen science data.
Making a difference at a local level can even address global issues, such as extinction risks. Citizen science may now re-define the phrase “think global, act local” to “think local, act local, network global”.
The I Spy a Wollemi Pine survey, for example, encourages people from all around the world to log sightings of Wollemi pine. These trees are cultivated in many countries, but fewer than 1,000 remain in the wild.
The simple act of paying attention to nearby trees means scientists can learn what environments the Wollemi pine can tolerate, and better protect it from extinction.
Technology advances have largely driven the explosion of citizen science projects over the last decade. Most people have a computer, camera and GPS in their pockets when they carry their smartphone, so taking part in a citizen science project has never been easier.
If you’re interested in joining a project, you can jump on board one that’s already established, or even develop your own for a common environmental issue in your local area.
You can search for citizen science programs through the Australian Citizen Science Project Finder. To help you get started, check out:
WomSAT: if you have a passion for wombats and are concerned about road mortality and disease (such as mange)
Sea Slug Census: snorkelers and divers can upload photos and discuss the identities of some of these weird and wonderful creatures
Australia’s wetlands are home to a huge range of stunning flora and fauna, with large snakes often at the top of the food chain.
Many wetlands are located near urban areas. This makes them particularly susceptible to contamination as stormwater, urban drainage and groundwater can wash metals — such as arsenic, cadmium, lead and mercury — into the delicate ecosystem.
We know many metals can travel up the food chain when they’re present in the environment. So to assess contamination levels, we caught highly venomous tiger snakes across wetlands in Perth, and repurposed laser technology to measure the metals they accumulated.
In our new paper, we show metal contamination in wild wetland tiger snakes is chronic, and highest in human-disturbed wetlands. This suggests all other plants and animals in these wetlands are likely contaminated as well.
Urban growth and landscape modification often introduces metals into the surrounding environment, such as mining, landfill and waste dumps, vehicles and roadworks, and agriculture.
When they reach wetlands, sediments collect and store these metals for hundreds of years. And if a wetland’s natural water levels are lowered, from agricultural draining for example, sediments can become exposed and erode. This releases the metals they’ve been storing into the ecosystem.
This is what we suspect happened in Yanchep National Park’s wetland, which was supposed to be our “clean” comparison site to more urban wetlands. But in a 2020 study looking at sediment contamination, we found this wetland had higher levels of selenium, mercury, chromium and cadmium compared to urban wetlands we tested.
And at Herdsman Lake, our most urban wetland five minutes from the Perth city centre, we found concentrations of arsenic, lead, copper and zinc in sediment up to four times higher than government guidelines.
In our new study on tiger snake scales, we compared the metal concentrations in wild wetland tiger snakes to the concentrations that naturally occurs in captive-bred tiger snakes, and to the sediment in the previous study.
We found arsenic was 20-34 times higher in wild snakes from Herdsman Lake and Yanchep National Park’s wetland. And snakes from Herdsman Lake had, on average, eight times the amount of uranium in their scales compared to their captive-bred counterparts.
Tiger snakes usually prey on frogs, so our results suggest frogs at these lakes are equally as contaminated.
We know for many organisms, exposure to a high concentration of metals is fatally toxic. And when contamination is chronic, it can be “neurotoxic”. This can, for example, change an organism’s behaviour so they eat less, or don’t want to breed. It can also interfere with their normal cellular function, compromising immune systems, DNA repair or reproductive processes, to name a few.
Snakes in general appear relatively resistant to the toxic effects of metal contamination, but we’re currently investigating what these levels of contamination are doing to tiger snakes’ health and well-being.
Snakes can be a great indicator of environmental contamination because they generally live for a long time (over 10 years) and don’t travel too far from home. So by measuring metals in older snakes, we can assess the contamination history of the area they were collected from.
Typically, scientists use liver tissue to measure biological contamination since it acts like a filter and retains a substantial amount of the contaminants an animal is exposed to.
But a big problem with testing the liver is the animal usually has to be sacrificed. This is often not possible when studying threatened species, monitoring populations or working with top predators.
In more recent years, studies have taken to measuring metals in external “keratin” tissues instead, which include bird feathers, mammal hair and nails, and reptile scales. As it grows, keratin can accumulate metals from inside the body, and scientists can measure this without needing to kill the animal.
Our research used “laser ablation” analysis, which involves firing a focused laser beam at a solid sample to create a small crater or trench. Material is excavated from the crater and sent to a mass spectrometer (analytical machine) where all the elements are measured.
This technology was originally designed for geologists to analyse rocks, but we’re among the first researchers applying it to snake scales.
Laser ablation atomises the keratin of snake scales, and allowed us to accurately measure 19 contaminants from each tiger snake caught over three years around different wetlands.
Our research has confirmed snake scales are a good indicator of environmental contamination, but this is only the first step.
Further research could allow us to better use laser ablation as a cost-effective technology to measure a larger suite of metals in different parts of the ecosystem, such as in different animals at varying levels in the food chain.
This could map how metals move throughout the ecosystem and help determine whether the health of snakes (and other top predators) is actually at risk by these metal levels, or if they just passively record the metal concentrations in their environment.
It’s difficult to prevent contaminants from washing into urban wetlands, but there are a number of things that can help minimise pollution.
This includes industries developing strict spill management requirements, and local and state governments deploying storm-water filters to catch urban waste. Likewise, thick vegetation buffer zones around the wetlands can filter incoming water.
Sun, sea … snakes: all three are synonymous with the Australian summer, but only the first two are broadly welcomed. And of all Australia’s snake species, brown snakes are among the most feared.
To some degree, this is understandable. Brown snakes are alert, nervy and lightning-fast over short distances. When threatened, they put on a spectacular (and intimidating) defensive display, lifting the front half of their body vertically, ready to strike.
They are also fairly common, and well adapted to suburban life – especially the eastern brown species. And of course, certain species have a highly toxic venom designed to immobilise the mammals they prey on.
Besides my work as a sociologist, I’m also a professional snake catcher and handle scores of venomous snakes during the warmer months. I don’t expect people to love snakes, but I believe greater knowledge about them will help with their being respected more as keystone ecological creatures.
Around two Australians die each year from snake bites, and the brown snake family causes the most human – and likely pet – fatalities. But compare that figure with the annual road toll (1,188 deaths in 2019) or the 77 people killed by horses and cows in Australia between 2008 and 2017. You can see why many herpetologists – or snake experts – feel our fear of snakes is somewhat misplaced.
Where does this fear come from, then? It partly arises from the representation of snakes throughout human history as menacing. The fact snakes are cold-blooded, with an unblinking stare, means humans have often depicted them as callous and cold-hearted. Examples include the serpent who corrupts Eve in the Book of Genesis, and monstrous mythological characters such as Medusa.
Partly because of these and other depictions, snakes are often considered something to be feared. When they slither into our manicured back yards, they are seen as a “problem” that has transgressed our sanitised domestic lives. And this fear is often transferred down the generations.
In my snake-catching work, I have extricated snakes from backyards and homes, a shopping centre, parks and school classrooms. I’ve even removed snakes from a woman’s boot, under a soccer team’s kit bag and inside a weapons bunker! About 85% of the snakes I work with on callouts are eastern browns.
Many callers wanting a snake removed experience intense emotions, from shock and hostility to awe and reverence. Most want the snake taken as far away from their property as possible.
After catching a snake, I release it into a suitable non-residential environment. I always wonder what happens to it next. The threats snakes face are numerous. They can be harmed or killed by humans, pets, feral animals or predators. They are also threatened by habitat loss, climate events and contaminated prey items.
I release each with the departing words: “Good luck fella, stay safe, stay out of trouble.”
Eastern brown snakes are timid and reluctant to strike unless provoked. They are generally solitary animals except during breeding periods. They perform a crucial ecological role by eating vermin such as mice and rats, controlling the numbers of other native species and providing a food source for various animals.
Information on how brown snakes move through and use urban space is limited. We urgently need more understanding of their daily habits, especially as urban development encroaches on their natural habitat, increasing the chances of conflict with humans or pets. More insight is also needed on whether it’s damaging to relocate hundreds of snakes each year.
A study in Canberra funded by the Ginninderry Conservation Trust aims to answer these issues. A team of researchers, including myself, will track the movements of 12 eastern brown snakes in the urban environment. We will do this using telemetry – tracking technologies fitted to the snakes. Some devices will be implanted into the snake under the skin, and others attached externally above the tail.
We will examine:
movements of adult male and female eastern browns
how far they travel
the times of day and temperatures when they are active
where they go dormant in the cooler months
the refuges they use to navigate the hostile environment they live in.
Our team will also explore the effects of catching a snake and releasing it into new habitat within a designated range (5km in the ACT, and 20km in NSW). We will examine how the snake responds to the stress of being captured and moved, the risks it might confront in an unfamiliar landscape, and whether it survives. We will also explore the implications for other snakes in the release habitat and the genetic consequences of interbreeding between geographically distinct populations.
We anticipate the study’s findings will help educate the public about how snakes operate in suburbia. It will also inform translocation policies and conservation efforts.
We also hope to show how eastern browns are vital – not superfluous or undesirable – parts of thriving ecosystems. The better we understand snakes, the less we might fear them. This may also mean we are less disposed to relocating or harming them.
How do we save whales and other marine animals from plastic in the ocean? Our new review shows reducing plastic pollution can prevent the deaths of beloved marine species. Over 700 marine species, including half of the world’s cetaceans (such as whales and dolphins), all of its sea turtles and a third of its seabirds, are known to ingest plastic.
When animals eat plastic, it can block their digestive system, causing a long, slow death from starvation. Sharp pieces of plastic can also pierce the gut wall, causing infection and sometimes death. As little as one piece of ingested plastic can kill an animal.
About eight million tonnes of plastic enters the ocean each year, so solving the problem may seem overwhelming. How do we reduce harm to whales and other marine animals from that much plastic?
Like a hospital overwhelmed with patients, we triage. By identifying the items that are deadly to the most vulnerable species, we can apply solutions that target these most deadly items.
In 2016, experts identified four main items they considered to be most deadly to wildlife: fishing debris, plastic bags, balloons and plastic utensils.
We tested these expert predictions by assessing data from 76 published research papers incorporating 1,328 marine animals (132 cetaceans, 20 seals and sea lions, 515 sea turtles and 658 seabirds) from 80 species.
We examined which items caused the greatest number of deaths in each group, and also the “lethality” of each item (how many deaths per interaction). We found the experts got it right for three of four items.
Flexible plastics, such as plastic sheets, bags and packaging, can cause gut blockage and were responsible for the greatest number of deaths over all animal groups. These film plastics caused the most deaths in cetaceans and sea turtles. Fishing debris, such as nets, lines and tackle, caused fatalities in larger animals, particularly seals and sea lions.
Turtles and whales that eat debris can have difficulty swimming, which may increase the risk of being struck by ships or boats. In contrast, seals and sea lions don’t eat much plastic, but can die from eating fishing debris.
Balloons, ropes and rubber, meanwhile, were deadly for smaller fauna. And hard plastics caused the most deaths among seabirds. Rubber, fishing debris, metal and latex (including balloons) were the most lethal for birds, with the highest chance of causing death per recorded ingestion.
The most cost-efficient way to reduce marine megafauna deaths from plastic ingestion is to target the most lethal items and prioritise their reduction in the environment.
Targeting big plastic items is also smart, as they can break down into smaller pieces. Small debris fragments such as microplastics and fibres are a lower management priority, as they cause significantly fewer deaths to megafauna and are more difficult to manage.
Flexible film-like plastics, including plastic bags and packaging, rank among the ten most common items in marine debris surveys globally. Plastic bag bans and fees for bags have already been shown to reduce bags littered into the environment. Improving local disposal and engineering solutions to enable recycling and improve the life span of plastics may also help reduce littering.
Lost fishing gear is particularly lethal. Fisheries have high gear loss rates: 5.7% of all nets and 29% of all lines are lost annually in commercial fisheries. The introduction of minimum standards of loss-resistant or higher quality gear can reduce loss.
Other steps can help, too, including
incentivising gear repairs and port disposal of damaged nets
penalising or prohibiting high-risk fishing activities where snags or gear loss are likely
and enforcing penalties associated with dumping.
Outreach and education to recreational fishers to highlight the harmful effects of fishing gear could also have benefit.
Balloons, latex and rubber are rare in the marine environment, but are disproportionately lethal, particularly to sea turtles and seabirds. Preventing intentional balloon releases and accidental release during events and celebrations would require legislation and a shift in public will.
The combination of policy change with behaviour change campaigns are known to be the most effective at reducing coastal litter across Australia.
Reducing film-like plastics, fishing debris and latex/balloons entering the environment would likely have the best outcome in directly reducing mortality of marine megafauna.
Lauren Roman, Postdoctoral Researcher, Oceans and Atmosphere, CSIRO; Britta Denise Hardesty, Principal Research Scientist, Oceans and Atmosphere Flagship, CSIRO; Chris Wilcox, Senior Principal Research Scientist, CSIRO, and Qamar Schuyler, Research Scientist, Oceans and Atmospheres, CSIRO
In recent months, three humpback whales were spotted in the East Alligator River in the Northern Territory’s Kakadu National Park. Contrary to its name, the river is full of not alligators but crocodiles. And its shallow waters are no place for a whale the size of a bus.
It was the first time humpback whales had been recorded in the river, and the story made international headlines. In recent days, one whale was spotted near the mouth of the river and scientists are watching it closely.
The whales’ strange detour threw up many questions. How did they end up in the river? What would they eat? Would they get stuck on the muddy river bank?
And of course, there was one big question I was repeatedly asked: in an encounter between a crocodile and a humpback whale, which animal would win?
The humpback whales were first spotted in September this year by marine ecologist Jason Fowler and fellow scientists, during a fishing trip. Fowler told the ABC:
I noticed a big spout, a big blow on the horizon and I thought that’s a big dolphin … We were madly arguing with each other about what we were actually seeing. After four hours of raging debate we agreed we were looking at humpback whales in a river.
The whales had swum about 20 kilometres upstream. Fowler photographed the humpback whales’ dorsal fins as evidence, and reported the unusual sighting to authorities and scientists.
Thankfully, two whales returned to sea on their own, leaving just one in need of help. There was concern it might become stranded in the shallow, murky tidal waters. If this happened, it might be attacked by crocodiles – more on this in a minute.
Experts considered a variety of tactics to encourage the whale back out to sea. These included physical barriers such as nets or boats, and playing the sounds of killer whales – known predators of humpback whales.
But none of these these options was needed. After 17 days, the last whale swam back to sea on its own.
The whale that spent two weeks in the river has recently returned and been spotted swimming around the mouth of the river. It appears to have lost weight – most likely the result of migration. It is now being monitored nearby in Van Diemen Gulf.
Questions are now being raised about the health of the animal, and why it has not headed south for Antarctic feedings waters.
There are various theories as to why they swam into the East Alligator River. Humpback whales are extremely curious, and may have entered the river to explore the area.
Alternatively, they may have made a navigation error – also the possible reason behind September’s mass stranding of pilot whales in Tasmania.
Long-term, a humpback whale’s chances of surviving in the East Alligator River are slim. The lower salinity level may cause them skin problems, and they may become stranded in the shallow waters – unable to move off the muddy bank. Here the animal might die from overheating, or its organs may be crushed by the weight of its body. Or, of course, the whale may be attacked by crocodiles.
In this case, my bet would be on the whale – if it was in relatively good condition and could swim well. Humpback whales are incredible powerful creatures. One flick of their large tail would often be enough to send a crocodile away.
If a croc bit a whale, their teeth would likely penetrate the whale’s skin and thick blubber. But it would take a lot more to do serious harm. Whale skin has been shown to heal after traumatic events, including the case of a humpback whale cut by a boat propeller in Sydney 20 years ago. Dubbed Bladerunner, it survived but still bears deep scars.
The whale sighting continues to fascinate experts. Scientists are hoping to take poo samples from the whale in Van Diemen Gulf, and could also collect whale snot to learn more about its health. However, the best case scenario would be to see the whale swim willingly to offshore waters.
This unusual tale will no doubt go down in Australian whale history. If nothing else, it reminds us of the vulnerability – and resilience – of these marine giants.
The author would like to thank Northern Territory Government whale expert Dr Carol Palmer for her assistance with this article.
The link below is to an article that addresses 6 myths concerning Australian snakes.
Environmental scientists see flora, fauna and phenomena the rest of us rarely do. In this new series, we’ve invited them to share their unique photos from the field.
Though it may not be as famous a stereotype as shrimps on the barbie, deadly snakes or Vegemite, Australia is renowned in certain scientific circles for being the “land of the lizards”.
Australia has a higher diversity of lizards than anywhere else in the world. The number of different species within a single part of remote, central Australia well exceeds similar desert environments, such as the Kalahari in Africa, or the US.
Over the last 50 years, scientists have tried to understand the cause of this extraordinary and unique diversity.
Some suggest unpredictable resources in the arid outback, such as sporadic rain, favour low-energy animals like lizards over birds and mammals. Others claim a high diversity of termites allows lots of different termite-eating lizards to co-exist.
Or perhaps the presence of shrubs, sparse trees and grass clumps provide a variety of niches (microhabitats) for tree and litter dwelling species. Despite these many hypotheses, no consensus has ever been reached.
My research explores the role of spinifex, a spiky clumping grass that’s typically found in the arid outback, often in conjunction with lizard diversity hotspots.
With many species found nowhere else on earth, some Australian lizards are threatened with extinction. Understanding how and why lizards use this iconic outback plant can help us conserve them, by predicting how they might respond to disturbances such as habitat loss and climate change.
Following many trips to the outback, I was surprised to find locals who had never encountered some of the species I was studying. Taking photographs of these often small and overlooked animals helps me to better engage the community and raise the wider public profile of lizards, compared to other, more “charismatic” native animals.
All 60 species of spinifex grasses (members of the Triodia genus) are found only in Australia. Although spinifex habitats cover more than one-fifth of mainland Australia, the plant is little-known and little-loved by non-naturalists.
But despite the close association of many lizard species to spinifex, we still don’t know exactly why reptiles like it so much.
Three ideas dominate. First, spinifex may contain lots of food for lizards, such as termites or ants.
Alternatively, the spiky, needle-like leaves of spinifex may offer small lizards a great place to hide from predators. And finally, temperatures deep within a dense spinifex hummock can be very cool compared to the searing desert heat, where temperatures can reach a scorching 50℃.
My research aim is to work out which, if any, of these explanations is true. I do this by measuring variables such as temperature, invertebrate abundance and risk of becoming prey, in spinifex and other plants.
Alongside my supervisors, I have also conducted behaviour trials on a couple of spinifex-loving lizard species: the mallee ctenotus (Ctenotus atlas) and the mallee dragon (Ctenophorus spinodomus).
We have recorded 230,000 temperatures, caught 16,089 invertebrates, constructed 112 lizard models and classified 143,627 behavioural observations. But such is the complicated nature of the work, we’re only partially closer to understanding the lizard-spinifex relationship. So far, our data suggests temperature is a key component.
The photos below are generally a result of good fortune and spending inordinate amounts of time in wild places. Pictures of some of the smaller, more skittish animals were taken upon release from pitfall traps.
The above two photos show my study species: the mallee dragon and the mallee ctenotus. Despite one lizard being a skink and the other a dragon, both species are strongly associated with spinifex. The skink tends to forage within spinifex, whereas the dragon emerges into open patches adjacent to spinifex to eat and “signal” to other dragons.
Spinifex grass, pictured above, with its spiky, needle-like leaves, creates valuable habitat for numerous species of birds, mammals and invertebrates — not just reptiles. Its abundance and influence on many species make it a “foundation species”.
This photo above shows a Burton’s legless lizard (Lialis burtonis) — a predator of my study species. These snake-like reptiles are specialist lizard hunters and often use the dense cover of spinifex to their advantage to ambush passing lizards.
Legless lizards might look a bit like snakes, but they have different ancestries and subtle distinguishing features, such as the lizard’s eyelids and external ears, which snakes don’t have.
But many other animals live in or near spinifex, and would happily make a meal of small lizards, including those shown in the following photos. The ability of numerous predators to access the centre of spiky spinifex clumps throws some doubt on the idea spinifex is used as protection from predators.
We can’t claim to have cracked the case yet. But we’re a step closer to unravelling the secrets behind one of Australia’s remarkable, and under-appreciated, biodiversity stories.
As we settle into spring and temperatures rise, snakes are emerging from their winter hideouts to bask in the sun. But don’t be alarmed if you spot one, it’s hard to imagine a more misunderstood group of animals than snakes.
Our interactions with snakes are conversation starters, with yarns told and retold. But knowing what’s fact and fiction gets harder with each retelling.
As is so often the case with wildlife, the myths pale in comparison to what science has shown us about these incredible creatures. So let’s debunk six misconceptions we, as wildlife ecologists, often hear.
This is a common old wives’ tale in southern Australia. The myth goes that if you see a red-bellied black snake or a blue-tongue lizard on your property, you’re unlikely to see the highly venomous brown snake, because black snakes keep brown snakes at bay.
This myth probably originates from observations of black snakes eating brown snakes (which they do).
But it’s not one-way traffic. There are many reported examples of brown snakes killing black snakes, too. Overall, no scientific evidence suggests one suppresses the other.
There is also no evidence blue-tongue lizards prey upon or scare brown snakes. In fact, many snakes feed on lizards, including brown snakes which, despite a preference for mammal prey as adults, won’t hesitate to have a blue tongue for lunch.
While the term poisonous and venomous are often used interchangeably, they mean quite different things. If you eat or ingest a toxic plant or animal, it’s said to be poisonous, whereas if an animal stings or bites you and you get sick, it’s venomous.
Why are some snakes so venomous?
Venom is a specialised type of poison that has evolved for a specific purpose. For venom to work, it needs a wound to enter the body and into the bloodstream. Snakes, therefore, are generally venomous, not poisonous.
But there are exceptions. For example, the American garter snake preys on the rough-skinned newt which contains a powerful toxin.
The newt’s toxin accumulates in the snake’s liver, and effectively makes this non-venomous snake species poisonous if another animal or human eats it. Remarkably, these snakes can also assess whether a given newt is too toxic for them to handle, and so will avoid it.
Approximately 20% of the world’s 3,800-plus snake species are venomous. Based on the median lethal dose — the standard measurement for how deadly a toxin is — the Australian inland taipan is ranked number one in the world. Several other Australian snakes feature in the top 10. But does that make them the deadliest?
If we define “deadly snakes” as those responsible for killing many people, then the list would be topped by snakes such as the Indian cobra, common krait, Russell’s viper and the saw-scaled viper, which occur in densely populated parts of India and Asia.
A lack of access to antivenoms and health care contribute substantially to deaths from snake bites.
Compared to other reptiles, such as monitor lizards, most snakes have poor eyesight, especially species that are active at night or burrow in soil.
However, snakes that are active by day and feed on fast-moving prey have relatively good vision.
One study in 1999 showed people are less likely to encounter eastern brown snakes when wearing clothing that contrasted with the colour of the sky, such as dark clothing on a bright day. This suggests they can see you well before you see them.
Some snakes such as the American coachwhip can even improve their eyesight when presented with a threat by constricting blood vessels in the transparent scale covering the eye.
And then there’s the olive sea snake, whose “phototactic tails” can sense light, allowing them to retract their tails under shelter to avoid predation.
This myth is based on the idea juvenile snakes can’t control the amount of venom they inject. No evidence suggests this is true.
However, research shows the venom of young and old snakes can differ. A 2017 study showed the venom of young brown snakes is different to adults, probably to facilitate the capture of different types of prey: young brown snakes feed on reptiles, whereas adult brown snakes predominantly feed on mammals.
Perhaps the most pervasive myth about snakes is they’re aggressive, probably because defensive behaviours are often misinterpreted.
But snakes don’t attack unprovoked. Stories of snakes chasing people are more likely cases where a snake was attempting to reach a retreat site behind the observer.
When threatened, many snakes give a postural warning such as neck flaring, raising their head off the ground, and opening their mouths, providing clear signals they feel threatened.
It’s fair to say this approach to dissuade an approaching person, or other animal, works pretty well.
Rhesus macaques display more fearful behaviour when confronted with snakes in a striking pose compared to a coiled or elongated posture. And showing Japanese macaques images of snakes in a striking posture sets of a flurry of brain activity that isn’t evoked when they’re shown images of snakes in nonthreatening postures.
The same is true for humans. Children and adults detect images of snakes in a striking posture more rapidly than a resting posture. And a study from earlier this year found human infants (aged seven to 10 months) have an innate ability to detect snakes.
Snakes are amazing, but shouldn’t be feared. If you encounter one on a sunny day, don’t make sudden movements, just back away slowly. Never pick them up (or attempt to kill them), as this is often when people are bitten.
Damian R. Michael, Senior research fellow, Charles Sturt University; Dale Nimmo, Associate Professor in Ecology, Charles Sturt University, and Skye Wassens, Associate Professor in Ecology, Charles Sturt University
Action came too late for the Christmas Island forest skink, despite early warnings of significant declines. It was lost from the wild before it was officially listed as “threatened”, and the few individuals brought into captivity died soon after.
Australia is home to about 10% of all known reptile species — the largest number of any country in the world. But many of our reptiles are at risk of the same fate as the Christmas Island forest skink: extinction.
In new research published today, we identified the 20 terrestrial snakes and lizards (collectively known as “squamates”) at greatest risk of extinction in the next two decades, assuming no changes to current conservation management.
While all 20 species meet international criteria to be officially listed as “threatened”, only half are protected under Australian environmental legislation— the Environment Protection and Biodiversity Conservation (EPBC) Act. This needs urgent review.
Many of these reptiles receive little conservation action, but most of their threats can be ameliorated. By identifying the species at greatest risk of extinction, we can better prioritise our recovery efforts — we know now what will be lost if we don’t act.
Our research team — including 27 reptile experts from universities, zoos, museums and government organisations across the country — identified six species with greater than 50% likelihood of extinction by 2040.
This includes two dragons, one blind snake and three skinks. Experts rated many others as having a 30-50% likelihood of extinction over the next 20 years.
More than half (55%) of the 20 species at greatest risk occur in Queensland. Three live on islands: two on Christmas Island and one on Lancelin Island off the Western Australian coast.
Two more species are found in Western Australia, while the Northern Territory, the Australian Capital Territory, Victoria and New South Wales each have one species.
Each of the 20 species at greatest risk occur in a relatively small area, which partly explains the Queensland cluster — many species in that state naturally have very small distributions.
Most of the top 20 occupy a total range of fewer than 20 square kilometres, so could be lost to a single catastrophic event, such as a large bushfire.
Reptile species are declining on a global scale, and this is likely exacerbated by climate change. In Australia, where more than 90% of our species occur nowhere else in the world, the most threatened reptiles are at risk for two main reasons: they have very small distributions, and ongoing, unmitigated threats.
The Cape Melville leaf-tailed gecko meets this brief perfectly. This large and spectacular species was only discovered in 2013, on a remote mountain range on Cape York. It’s threatened by virtue of its very small distribution and population size, and by climate change warming and drying its upland habitat.
Habitat loss is also a major threat for the top 20 species. Australia’s most imperilled reptile, the Victoria grassland earless dragon, used to be relatively common in grasslands in and around Melbourne. But the grasslands this little dragon once called home have been extensively cleared for agriculture and urban development, and now cover less than 1% of their original extent.
For most reptile species, there has been less conservation work to address the declines, partly because reptiles have historically received less scientific attention than birds or mammals.
We also still don’t fully understand just how many species there are in Australia. New reptile species are being scientifically described at an average rate of 15 per year (a higher rate than for other vertebrate groups) and many new reptiles are already vulnerable to extinction at the time of discovery.
To make matters worse, few reptiles in Australia are well-monitored. Without adequate monitoring, we have a poor understanding of population trends and the impacts of threats. This means species could slip into extinction unnoticed.
Reptiles also lack the public and political profile that helps generate recovery support for other, (arguably) more charismatic Australian threatened animals — such as koalas and swift parrots — leading to little resourcing for conservation.
Only one Australian reptile, the Christmas Island forest skink, is officially listed as extinct, but we have most probably lost others before knowing they exist. Without increased resourcing and management intervention, many more Australian reptiles could follow the same trajectory.
But it’s not all bad news. The pygmy bluetongue skink was once thought to be extinct until a chance discovery kick-started a long conservation and research program.
Animals are now being taken from the wild and relocated to new areas to establish more populations, signifying that positive outcomes are possible when informed by good science.
And the very restricted distributions of most of the species identified here should allow for targeted and effective recovery efforts.
By identifying the species at greatest risk, we hope to give governments, conservation groups and the community time to act to prevent further extinctions before it’s too late. Neglect should no longer be the default response for our fabulous reptile fauna.