Road Block - are you commuting again?

Roads are essential for human existence. They are indispensable, unavoidable and the largest human artefact of all, spanning the entire globe, connecting everywhere with everywhere else. Despite all that, they are effectively invisible.

We almost never even think about them as we commute to work, or start to commute again as we uneasily emerge from the restrictions on travel that were imposed on everyone. As we start up the car, the natural world is probably regretting our return to driving. In many places, throughout the pandemic, the suddenly car-less roads and freeways were invaded by all sort of bewildered animals enjoying the peace and quiet. And the safety of not having to dodge speeding vehicles.

If we actually think about roads at all, it’s usually a simplistic ‘getting from A to B' as fast and directly as possible. In other words, a single line on a map. In reality, roads are webs or nets, spread over the landscape, severing connections between parts of the countryside and leading to fragmentation and isolation. As the network of roads expands, the land is sliced into pieces, now separated from each other. This perspective is new and unsettling but it is leading to some big changes in the way roads are envisioned and planned.

For most species, moving in any direction will unavoidably bring them to a road. For small country roads with little traffic, moving to the far side is virtually risk free, especially at night. As the traffic volume and road width increases, however, crossing safely becomes far more difficult and dangerous. For smaller, slower animals, the risks can be insurmountable.

Sometimes it’s possible to erect a fence to keep animals away from the traffic. However, this obviously makes the road an even greater barrier. It is crucially important that animals are able to travel through the landscape to seek space, food and mates. But they need to be able to do this safely. How is that possible?

If you are commuting to work by car consider this. Beneath virtually every road are pipes and culverts constructed to allow water to pass through the road corridor. Most of these passageways were built for water and are often too small or too wet to be useful. However, it doesn’t take much thought to design a culvert that can accommodate wildlife species instead. Fauna-specific underpasses have been constructed throughout the world, from frog-sized in Belgium during the 1950s to elephant-sized in Kenya only last year.

Not every species is able or wants to enter a dark concrete tunnel. Many are too large, however they might move over the road if that was possible via some structure. The first such structures were small wooden bridges built for deer in nineteenth century France. These simple overpasses have been up-scaled massively over the last couple of decades. Now, vast artificial hills span hundreds of multilane motorways and railways around the world. Every conceivable species now wanders safely across, hardly aware of the endless traffic passing beneath.

Purpose-designed wildlife overpasses were initially designed with specific, usually large, mammal species in mind. In Europe, the main species of concern are the various species of deer. Reducing collisions between cars and wildlife has been a predominant motivation for road authorities for years. But deer – and their Australian equivalent, kangaroos – are very wary of anywhere that might conceal a predator. As a result, most overpasses are simple grassy slopes providing a wide panorama for nervous herbivores to be able to see if the coast is clear. However, plenty of other species prefer the exact opposite: dense foliage or other habitat features that provide cover and places to hide. Encouraging these species to use the overpass required a rethink of design, resulting in some being planted with trees and shrubs stretching the entire length of the structure. These were immediately utilised by a wide variety of smaller and less conspicuous species such as ground-dwelling mammals, reptiles and amphibians.

In Australia, the Compton Road overpass in the Brisbane suburb of Kuraby was constructed to reduce collisions and allow wildlife to safely move between the conservation reserves on either side. Since being built in 2005, our research group based at Nathan has been looking at all the animals that might use the structure: snakes, lizards, frogs, mammals large, small and arboreal, bats and birds. Apart from the astonishing variety of species using the overpass most days and nights, two discoveries have been particularly noteworthy.

First, like most road ecologists, I saw the structure as a means simply for safely crossing the road. Yet, when we looked more closely, quite a number had made it their home; they live their lives in the planted ecosystem despite its artificial nature (every part of it had been put in place by people). In fact, more species of frog live on the structure than in the forest nearby.

Second, I freely confess that, even though I am a bird ecologist, I had not even thought about birds. They would simply fly across Compton Road, wouldn’t they? But I eventually realised the that many smaller species live in the thickets and understory of the forest and never move very far from this cover. Compton Road – and indeed every road that dissects a forest anywhere is effectively severing populations of the local small birds permanently. It was a shocking realisation.

But within five years of growth of the planted vegetation on the overpass dozens of species began to move freely through the expanding undergrowth and tree canopies. For the first time in decades, those little birds were able to cross the road and, more importantly, interact with their relatives on the other side.

As we start to reimagine our working lives, and what that means for our daily commute, we should also start reassessing what’s important. If we choose to work from home it’s because we are attempting to strike a work/life balance. The Covid era has led to a lot of deliberate refocusing of priorities

While these considerations are often about our individual needs and preferences, there are also benefits for the natural world. With less driving, we reduce consumption of non-renewable resources and carbon emissions. But less driving also means we can take a moment to consider what is often ignored, the actual roads themselves. They are a legacy of how we did things before. And everyone, including tiny birds and critters we rarely see, have been impacted.

What comes next?

Road ecology is more than simply building amazing structures for wildlife. In contemplating our return to work, we also need to think about something as fundamental as what sort of world we want in the future.

Professor Emeritus Darryl Jones is an urban ecologist, academic, lecturer, public speaker and author based at Griffith University in Brisbane. He is especially interested in the interaction between people and wildlife, particularly in cities. For over 30 years he has investigated the ecology of species such as brush-turkeys, magpies, possums, ibis and crows – all associated with conflicts – as well as the positive relationships. This has resulted in his books The Birds At My Table, Feeding The Birds At Your Table, Curlews on Vulture Street, & A Clouded Leopard in the Middle of the Road.

He has published seven books and over 200 scientific articles, and frequently appears in the media.