Teaching wildlife road-crossing tricks


Do you know the most common question I get about wildlife crossing structures? Surprisingly, it’s not ‘do they work?’. It’s ‘how do you teach them how to use it?’. I understand why people are skeptical. Sure, a big, safe bridge for wildlife sounds like a great idea, but animals aren’t smart enough to know the difference between a safe spot and a dangerous spot. Are they? After all, they can’t even read! said no animal ever Thankfully, we don’t have to rely on wildlife commonsense. We road ecologists have a few tricks up our sleeves to make sure that animals do use these structures and don’t just cross wherever they feel like.

Location location location

Ideally, we’ve had a chance to study the animals living nearby before the road and crossing structures are put in. We spy on them with cameras, track them with GPS collars and generally stalk them about the country-side. If we can’t track them, we often know a bit about where they like to move through – do they travel along gullies or follow forest patches? From this we can build a map that shows their main movement corridors and pathways. Then we overlay where the new road will be built. Wherever the animal path crosses the road path is a good place for a structure. That way the animals don’t have to change their behaviour too much. They were going that way anyway.

A little bit of guidance

Still, animals have minds of their own and ultimately, can cross wherever they see fit. Maybe one day a new family moves in and decide they’d like to make a new path, a few 100 m away. How do we stop all our careful planning going to waste?

The fencing around the bottom to guides these Christmas Island crabs up and over

The fencing around the bottom to guides these Christmas Island crabs up and over

A fence. I know, it’s obvious when you think about it. We can put up fences where we don’t want animals to cross. Fences serve two important functions. First, they stop animals getting onto the road, creating traffic havoc and potentially getting killed. Second, fences guide animals to the structures, so that the structure is the only place the can cross. Unfortunately, fences can’t go on forever (that’s a lot of fencing!) but targeting them around key movement paths and crossing structures can be really effective.

It doesn’t happen overnight

Even with great planning and fencing, there can be a learning curve. Imagine you’re a deer. You’ve woken up in the morning and are heading off to your favourite waterhole for a quick drink before a day of frolicking (I assume this is how deer behave). Trotting merrily along, all of a sudden you come across this…thing, in your path. A strange, hard tunnel. You can see the waterhole on the other side, but the tunnel smells odd, and looks funny and generally gives you the heeby-jeebies. Better not risk it. Next time you come across the tunnel you’re feeling braver. The smell is fading and grass has started to grow around it. You might take a few steps inside before you chicken out. Then you take a few steps more, and more, until one day, you’ve made it all the way through. You think ‘Nothing bad happened. Maybe I’ll try that again… ‘ Anthropomorphism aside, animals usually take time to get used to the structures. How much time depends on the species. Black lion tamarins used a canopy bridge “as soon as it was assembled” (Valladares-Padua 1995), while larger, long-lived animals could take decades to adapt. My own work on squirrel gliders showed took up to 2 years before they started regularly using canopy bridges and glider poles (Soanes et al 2013).

Not just a cute idea

So, that’s how we do it. Scientists, engineers, road planners and environmental managers put a lot of thought into making each one as good as possible. After a structure is built there’s more work to do, figuring out how well it works and perfecting designs to make future structures even better. I’m not saying we’ve got it all figured out yet – there’s still a long way to go – but we’re learning all the time how to make safer roads for people and animals. Although this guy seems to have the situation under control…

“Don’t worry, ecologists. I got this.”

References and further reading

Valladares Padua C, Cullen Jr L and Padua S (1995) A pole bridge to avoid primate road kills. Neotropical Primates 3, 13-15.

Soanes K, Lobo MC, Vesk PA, Moore J, McCarthy MA and van der Ree R (2013) Movement re-established but not restored: Inferring the effectiveness of road-crossing mitigation for a gliding mammal by monitoring use. Biological Conservation 159, 434-441.

van der Ree R, Gulle N, Holland K, van der grift E, Mata C, Suarez F (2007) Overcoming the barrier effect of roads – how effective are mitigation strategies?, In International Conference on Ecology and Transportation. eds C.L. Irwin, D. Nelson, K.P. McDermott, pp. 423-431, Centre of Transportation and The Environment, North Carolina State University, Raleigh, North Carolina and Little Rock, Akansas, USA.

Conservation at the cross-roads

In August I had the absolute pleasure of hosting a road ecology symposium at the ICCB-ECCB, an international conference on conservation biology. It was a pleasure not just because it was summer in the south of France (ooh la la) or because I got to eat chocolate croissants and soft cheese every day, but because of the quality of the people I was able to work with and the enthusiasm they brought to our symposium.

Dan Smith, Clara Grilo, Rodney van der Ree and myself wanted to organise a symposium that showcased the global importance and diversity of road ecology research, and highlight how critical this issue is to conservation. With over 30 authors across 15 countries contributing to the presentations, we think we achieved that! The topics ranged from building predictive models to guide mitigation efforts, to the complex challenges facing management in developing nations, the importance of road-free areas and the opportunities for citizen science.

We’ve compiled the abstracts from our symposium into a ‘mini-proceedings’ booklet, which includes links to relevant papers and websites as well as the authors’ Research Gate profiles so that you can easily find out more about their work.

Click on the cover page to download pdf
Conservation at the Crossroads_cover

It was fantastic to see that weren’t the only ones talking about road ecology at the conference, with several other sessions dedicated to the topic. It’s exciting to see how the field is growing! Thanks to the magic of live-tweeting, you can catch up on all the presentations, discussions and papers with this handy Storify newsletter.

I hope you find these resources helpful, particularly for those who were unable to attend the conference. Feel free to spread them through your networks.

Until next time, I’ll leave you with this snapshot which sums up the atmosphere in Montpellier. If only the cat were wearing a beret. So Francey.
le chat noir_ksoanes

Threat: Terror-firma for urban arboreals


How do arboreal mammals cope living in urban areas? It can be a bit of a balancing act. See this post from the Urban Safari Guide for more…

Originally posted on Urban Safari:

Welcome to the first of my ‘Threat’ posts, where I describe some of the challenges facing urban wildlife.

I spotted this poor old possum on the side of the road in Torquay a few weeks ago. And another just yesterday. For tree-dwelling mammals, city-living can be as dangerous as it is lucrative.
Unlucky possum Unlucky possum

In most cities and towns across Australia, the only small native mammals you’re likely to see will be the arboreals – the tree-dwellers. Koalas, possums and gliders can be spotted in even major cities.

One of the reasons arboreal mammals have managed to survive in the urban jungle is because they spend a lot of their time out of harm’s way. High in the canopy they’re safe from cars, cats, dogs and foxes. Interconnected tree branches and overhead power lines mean they can roam unrestricted by fences, making the most of the lush banquet provided by…

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Roads, wildlife and a finished thesis

With the thesis finally vanquished (more on that in a later post), it’s high time I put together a bit of a summary of what I found. Thankfully I had the opportunity to write an article for the Ecological Society of Australia’s Bulletin which does exactly that, so I’ll repost it here. Make sure you check out the rest of the ESA Bulletin (here). It’s a cracker of an issue if you’re interested in anything to do with urban ecology.

So, with no further ado, here’s a bit of an overview of my field, my study and some very cool Australian mammals.

Roads, (huh) what are they good for?
People depend on roads. We use them to get to work, to move goods around the country or to take an iconic road trip. That’s probably why in Australia we have over 800 thousand kilometres of roads, driven by more than 15 million vehicles. But our need to travel can take a toll on the environment, especially our native wildlife.

The spread of roads across Australia. The areas in dark green are more than 1 km from the nearest road. The white areas are not. (credit Google Earth Engine)

The spread of roads across Australia. The areas in dark green are more than 1 km from the nearest road. The white areas are not. (credit Google Earth Engine)

The most obvious issue is roadkill. We’ve all seen the carcasses that litter the roadsides and maybe we’ve even been unlucky enough to hit an animal ourselves. Most motorists wouldn’t realise that the roadkill problem reaches far beyond the unlucky individual. When many animals are killed it can drain the local population, reducing numbers to a point where species can become locally extinct.

Then there are effects that aren’t so obvious. Some animals avoid walking out on to the road’s harsh, unfamiliar surface or shy away from the noise and open space. Others can’t physically make it across the gap a road creates in their habitat. This means they’re trapped on one side of the road, unable to reach food, shelter or mates on the opposite side.

I work in the field of road ecology, where we try and understand the environmental impacts of roads, trains and other linear things and find ways to put a stop to all of this carnage. When it comes to wildlife, we often build wildlife crossing structures – bridges over roads or tunnels under them – to allow animals to cross safely on their own. But how well do these structures work? I aimed to answer this question for one of our threatened mammals, the squirrel glider.

A threatened species in a threatening landscape
The squirrel glider is a small gliding marsupial that is threatened with extinction in the south-eastern parts of its range. They move by gliding from tree to tree, with an average distance of 30–40 m. Gliders depend on mature woodland with big old hollow-bearing trees. Unfortunately, in my study landscape of north-east Victoria, all that’s really left of the pre-European woodland occurs in linear strips, mostly along roadsides. So to conserve this species we need to make sure that they can survive and flourish in roadside habitats.

The only woodland that's left is along roadsides, paddocks and waterways.

The only woodland that’s left is along roadsides, paddocks and waterways.

One such roadside is the Hume, a four-lane interstate freeway. It’s travelled by about 10,000 vehicles per day, 25% of which occurs at night when native mammals like the squirrel glider are most active. The freeway ranges from 50–100 m wide and has been this way since it was upgraded around 40 years ago.

The problem
Those of you who are great at maths will have noticed that the width of the freeway is generally further than a squirrel glider can glide. Some researchers got to work investigating what sort of impact this had on squirrel glider populations. Through radiotracking studies they discovered that where treeless gap across the freeway was wider than 50 m, glider movement was heavily restricted (only 1 out of 50 crossed). Researchers also conducted mark-recapture surveys over 2.5 years and found that the survival rates of squirrel gliders living next to the freeway were 60% lower than those living further away. Gliders living along the freeway were facing a few challenges.

That's quite a gap for a small animal!

That’s quite a gap for a small animal!

Safe crossings for high-flying mammals
As a solution, two types of crossing structure were installed along the Freeway in 2007 – canopy bridges and glider poles. Canopy bridges are a kind of rope ladder, allowing animals to scurry across above the traffic. Glider poles are tall, wooden poles placed in the roadsides and centre median, and act as ‘stepping-stones’ for gliders to cross in a few short glides. Given that prior research had highlighted two key problems – barrier and survival effect – I wanted to see if crossing structures would increase movement across the road and improve the survival rates of squirrel gliders that lived alongside the freeway.
A rope bridge over the Hume Freeway in Victoria (left) and glider poles on the Hume Freeway in New South Wales (right)

A rope bridge over the Hume Freeway in Victoria (left) and glider poles on the Hume Freeway in New South Wales (right)

Spying and stalking
The first thing I looked at was animal movement, installing motion-triggered cameras to see if squirrel gliders would actually use canopy bridges and glider poles to cross the freeway. It took about two years before squirrel gliders got used to the structures and started crossing them regularly. In the seven years since, we’ve detected 1000’s of crossings. Gliders weren’t the only species making the most of the crossing structures. We also spotted brushtail possums, ringtail possums, sugar gliders, brush tailed phascogales and even a lace monitor making the trek across the freeway.
Squirrel Glider on a rope bridge over the Hume Freeway in north-east Victoria.

Squirrel Glider on a rope bridge over the Hume Freeway in north-east Victoria.

I was also able to look at movements in a little bit more detail. There were microchip scanners installed on the bridges so that if an already tagged animal went across, we’d know who it was. This showed me that several different individuals crossed the canopy bridges, some of them multiple times each night to reach habitat on both sides of the road. I worked with a masters student Meli Carmody, who repeated that earlier radiotracking study to investigate how road crossing behaviour had changed after the structures were installed. It turned out that where canopy bridges or glider poles had been installed, squirrel gliders were now able to cross the freeway at sites that had previously been a barrier to movement. At sites that were left with no structures, the freeway remained a barrier. This shows us that regular movements across the Hume Freeway wouldn’t be possible without crossing structures in place.
Our monitoring set up, complete with camera, microchip scanner and solar panels.

Our monitoring set up, complete with camera, microchip scanner and solar panels.

Gene flow
All this crossing activity was great, but did it result in gene flow? Were the animals that crossed the road “getting lucky” on the other side? To find out, mark-recapture surveys were conducted along the freeway to obtain tissue samples from squirrel gliders before and after the structures were installed. I was then able to use their genetic data to conduct a parentage analysis – identifying paternal and maternal relationships between individuals that lived on opposite sides of the freeway.

The analysis revealed that at sites where crossing structures were present, offspring occurred on the opposite side of the freeway to one or both of their parents. Somebody had to cross the road for this to happen! By cross-checking the identity of these family members with data from the cameras and microchip scanners, I was able to confirm that they had used the canopy bridges to cross the freeway. This reproductive success is an important component of gene flow and the effectiveness of crossing structures. Overall, I found that installing a crossing structure resulted in detectable improvements to gene flow within just five years.

A slide from one of my presentations, showing how family members occur on opposite sides of the freeway where a rope bridge is present.

A slide from one of my presentations, showing how family members occur on opposite sides of the freeway where a rope bridge is present.

Surviving in the danger zone
Finally, how did the crossing structures influence survival rates? The earlier mark-recapture study had identified a negative effect of the freeway on glider survival. I repeated that study, surveying for an additional five years after the structures were installed to see if survival rates had improved.

The results were surprising. It turns out that many of the animals that were missing and presumed dead at the end of the first study, were actually alive, and detected during later surveys in the second study. So the longer sampling period gave us a better estimate of survival rates because we had more of an opportunity to recapture previously tagged animals.

In light of all the other information, this finding actually makes a bit more sense. Radiotracking showed that gliders rarely crossed the road at sites where there were no crossing structures. If they’re not crossing the road, they can’t get hit by cars and so we wouldn’t expect survival to be reduced.

Monitoring effort matters
There’s more work to do, but ultimately my research suggests that crossing structures successfully reduce the effect of the road on squirrel gliders. I’ve showed that canopy bridges and glider poles can allow squirrel gliders to regularly cross the Hume Freeway, giving access to habitat on both sides as well as facilitating genetic exchange. But what I’ve really tried to show is that by using a comprehensive monitoring program we can be much more confident about how effectively crossing structures mitigate the negative impacts of roads on wildlife. Having information on movement, gene flow and survival collected before and after structures are installed was critical to getting the full picture.

When new roads are built, crossing structures are often installed as part of the environmental conditions of approval – granting permission for a road to potentially cause damage, on the assumption that a wildlife bridge or eco-tunnel will do the trick. If it turns out that these structures don’t work as well as we expected, not only are we wasting money on ineffective conservation measures, but we won’t know if we should be trying other things instead, or even seriously reconsidering where we allow roads to be built. Scientifically robust monitoring programs are the only way to truly understand these issues and make smart decisions for conservation.

As human populations spread, very few landscapes will remain road-free. Roads already cut through our national parks, conservation reserves and protected wildlife corridors. We must find ways of getting where we need to go without spoiling our natural heritage.

Related publications
Soanes K, Carmody Lobo M, Vesk PA, McCarthy MA, Moore JL, and van der Ree, R. (2013) Movement re-established but not restored: inferring the effectiveness of road-crossing mitigation by monitoring use. Biological Conservation. 159: 434–441.

McCall S, McCarthy MA, van der Ree R, Harper MJ, Cesarini S and Soanes K (2010) Evidence that a highway reduces apparent survival rates of Squirrel Gliders. Ecology and Society 15.

van der Ree R, Cesarini S, Sunnucks P, Moore JL, Taylor A (2010) Large gaps in canopy reduce road crossing by a gliding mammal. Ecology and Society 15.

How to spot a late-stage PhD student

one does not simply, finish a phd

Yep, I’ve reached that stage of PhD research. The stage when you suddenly realise your analyses are mostly completed. You have graphs. You have answers. The only thing left is to figure out what the hell you think about them. And then to write it all down.

As a late-stage PhD researcher, you may exhibit some or all of the following behaviours.

You’ve stopped going to lab meetings. You no longer attend interesting seminars. You forgo group BBQs and faculty morning teas, except to quickly swoop through and pilfer some free food.

You start skipping committee meeting and workshops. At first you respond to invitations with thoughtful apologies. But eventually the list of unread or ignored emails looms large.

Your dependence on performance enhancing substances increases; caffeine, sugar and alcohol, all in your favourite forms (I like redbull, chocolate and wine).

You might even find yourself annoyed when you are forced to attend weddings, birthdays and other social distractions that other (normal) people look forward to.

I could say, ‘Maybe it’s just me…’ But I know I’m not alone. I know you’re out there. Single-mindedly dedicated to finishing your thesis, while at the same time desperately trawling the internet for anything, ANYTHING, to distract you. Perhaps you’ve stared at a word on the screen for so long that you’re sure it’s misspelled. Perhaps that word is your name.

Then again, maybe not. You might be a well-organised and well-adjusted individual. You might work solidly until 5pm then go home, not giving your thesis a second thought until you return at 9am the next morning. I might like to hide thumbtacks in your chair.

Try not to feel guilty about the borderline-antisocial behaviour that comes with late-stage thesis writing. It will pass. You’ll be a doctor soon! It’s right there. Tantalisingly and tortuously close.

In the mean time, take care of yourself and embrace your membership to this club of recluses. You can recognise other members by their complete ignorance of current movies or music and the inability to talk about anything other than their thesis.

Fear not my friends, for this is the stage of finishing! Finally your story comes together. All you have to do, is re-arrange that argument for the 100th time – then delete it entirely.

Further reading
Evidently, for some of us this is also the stage where we can no longer bear the self-imposed embargo on writing anything other than the thesis, and we rebel with a cheeky blog post. I recommend the following:
A letter to my thesis – Samantha Prendergast (One of my favourite reads)
Dear Thesis Whisperer, I’ve got Stockholm Syndrome – Ben from Literature Review HQ (via the Thesis Whisperer)
The nowhere-everywhere place – Maia Sauren (via the Thesis Whisperer)
When are you really finished with a PhD?– Lauren Gawne (via the Thesis Whisperer)

Introducing the Australasian Network for Ecology and Transportation

If you’ve read any of my previous posts, you’ll know that roads and traffic take a toll on the environment. You’ll also know that there is a whole field of research devoted to understanding and fixing the problem. Road ecology.

ksoanes_wildlife crossing

All over the world, road agencies, environment groups and scientists work to reduce the impacts of roads on the environment. They might build wildlife overpasses, reschedule construction so it doesn’t disrupt mating season, close roads during sensitive times or avoid building roads through protected areas. The details of these stories – successes, failures, and surprises – are often filed away on office shelves and forgotten. That’s the beauty of road ecology organisations like ICOET in the US and IENE in Europe. These networks hold regular meetings and conferences, ensuring that valuable lessons are shared.

Now one more group has set out to make information on road ecology more available – the Australasian Network for Ecology and Transportation, or ANET. To lift text straight from their website:

“We are a professional network dedicated to the research, design and implementation of environmentally-sensitive linear infrastructure (rail, roads and utility easements) across Australasia. ANET acts as a hub, providing links between government, industry, scientists and community groups to ensure all have access to current evidence and best-practice.”

While the network’s focus is on Australia, New Zealand and Asia, it’s open to anyone to join (it’s free) and contribute. In July 2014 the first ANET Conference will be held in Australia, showcasing the latest road ecology research.

Check out their website, Facebook and Twitter (@ecoltransnet) for more info and updates on road ecology, both here and abroad. Full disclosure, while this post isn’t on behalf of ANET, I am involved in the steering committee and run the Facebook and Twitter pages – so I’m not entirely impartial. Even so, I think it’s all pretty great and I’m excited to see how the network grows!