Perilous passage: tackling Tasmania’s roadkill problem

Perilous passage: tackling Tasmania’s roadkill problem

In January 2020, shortly before lockdown measures disallowed travel, I was fortunate enough to visit Tasmania with my family. The state is in a unique position when it comes to Australian wildlife. By virtue of Bass Strait, foxes and dingoes have never made it to the island, allowing a great concentration of native fauna which draws many tourists.

While introduced predators pose little threat to Tasmania’s animals, our cars do. The state’s roads are notorious for roadkill, with dead animals lining the roads far more frequently than I have ever seen before, and in numbers many times greater per kilometre than in Victoria.

With almost 50% of visitors to Tasmania participating in some type of wildlife-based activity while visiting the state, roadkill has a two-pronged negative effect on tourism. It both kills the animals which people come to see and can have an offputting effect for tourists due to the gruesome sights. Roadkill also begets more roadkill, as carnivores that come to the road to feed can be hit by vehicles in turn.

On average, 32 animals are killed every hour on Tasmanian roads. This totals almost 300,000 animals per year — the world’s highest rate of animal deaths per kilometre of road. The risk of collisions is heightened in the state, as nearly all of Tasmania’s mammals are nocturnal, and most are dark-coloured for camouflage, making them hard for motorists to see. These collisions don’t necessarily kill the animal — they may injure it, inflicting pain which can linger for the remainder of the creature’s life, whether hours or years.

Tasmania’s most charismatic and recognisable animal species is naturally the Tasmanian Devil, but Tasmania is also home to many other species, both vulnerable and adorable. The latter is important to the state’s economy because it draws tourists to the state. Due to its recognisability, 154 roadkill surveys in the early 2000s identified the Tassie Devil more than all but seven other species, despite its rarity. The Save the Tasmanian Devil Program Roadkill Project was launched in 2009 to track the Devil road toll and has found  over 350 on average are killed on roads each year.

Tasmanian Devils were classified as ‘least concern’ by the International Union for Conservation of Nature just a few decades ago, but due to the persistent and fatal facial tumour disease, this classification has increased to ‘endangered’. Intense government action and deliberate isolation of infection-free populations have been important conservation measures as insurance against the disease.

The outlook for the Tasmanian Devil is looking brighter – but they are still very vulnerable to road traffic. Image: Mathias Appel via Flickr [CCO 1.0]
Another notable species in Tasmania is the near-threatened Tiger Quoll, which is now much worse off than it was just a few years ago, as its range overlaps heavily with the 2019/20 summer’s fires. In a far worse state, however, is the Eastern Quoll. The species was wiped out on the mainland in the 1960s, but several reintroduction programs since 2002 have aimed to re-establish mainland populations within fenced sanctuaries. The survival rates for these mainland quolls are gradually improving, but for the time being the survival of the species rests predominantly on its success in Tasmania.

 

In the decade before 2004, three people in Tasmania were killed in car accidents involving wildlife while 72 were injured, and over five million dollars of vehicle damage caused. Roadkilling of wildlife disadvantages all Tasmanians, with the danger to drivers, unpleasant roadside scenes and economic loss affecting everyone.

Government action is a crucial factor in addressing roadkill, but solving the problem is not as simple as throwing money at it. I visited East Coast Natureworld and spoke to one of their staff about the issue. Though he was from the UK, he was passionate and strongly committed to protecting Australian wildlife. He said that different methods of preventing roadkill work for different animals, making finding a solution complex.

There is a general lack of knowledge about the effectiveness of different methods in preventing roadkill. Tunnels under roads allow some animals to cross safely, while bridges work for others. The lack of a one-size-fits-all solution makes preventing roadkill difficult, as it means that any money spent requires supporting some animals over others.

There is shockingly little research on the effectiveness of most methods of preventing roadkill. Some methods include wildlife signage, renovating roadsides to flatten land, and the aforementioned bridges. One small study used a combination of rumble strips, animal signage and vegetation clearing to great effect. A thorough, scientific comparison of the effectiveness, and just as importantly, the cost-effectiveness of these methods would be extremely useful. However, such a study would require significant financial resources.

road signs are one method of attempting to reduce roadkill
Road signs are one method of attempting to reduce roadkill. Image: Sarah Thomson

One promising new method is installing virtual fences — a series of posts along roadsides that, when hit by car headlight, produce noise and light intended to drive animals away. Evidence for their effectiveness is mixed — some studies find great benefit, while another noted reduced roadkill in only one of the four studied species. It makes sense that the effectiveness of virtual fences depends on the local conditions; the technology may not work as well on a fast, wide road. Costing $9000 per kilometre to purchase, more research is also needed to ensure its cost-effectiveness.

Constructing tunnels beneath roads is one of the few methods known to reduce roadkill, but many unknowns remain as to the species for which they are effective. This is because a number of factors prevent animals from using them — for instance, fear of predators and avoidance of enclosed, dark spaces or even just the ground itself. These are likely to vary significantly based on the size and shape of the passage, but large tunnels can be prohibitively expensive. The Natureworld staff member noted that, in the case of carnivores like Devils, tunnels can cause the animals to spend more time around roads by hunting prey that traverse them. He also said territorial animals can occupy the tunnels and stop others from using them.

Roadkill peaks in summer with young mammals leaving their dens and pouches and beginning to disperse. Amplifying this risk is the lack of new plant growth, which forces animals to travel further to find food. Water runoff from roads encourages plant growth on the roadside, which can attract herbivores, meaning roadkill is worse in drought years.

We have some amazing fauna in Tasmania which are found nowhere else in the world, and we all need to play our part in keeping them safe. Here are a few tips to help them stay alive along roadways:

  • To avoid hitting animals when driving, don’t try to swerve, simply slow down.
  • Remove animal carcasses from the road to avoid attracting carnivores which can be hit in turn. Keep a pair of thick gloves and a towel in the car for this purpose.
  • Remember your own safety: only stop if it’s safe to do so, and never handle a Tasmanian Devil.

With new research giving us reason to be optimistic about the Tasmanian Devil defeating facial tumour disease, and the growing interest in their reintroduction to the mainland, we have all the more reason to do everything we can to protect some of our most beloved native fauna.

 


Banner image by Nico Smit on Unsplash

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