Wildlife crossings: the road network for animals

Solutions such as ecoducts allow animals to bypass the fractures in the territory caused by transport networks. Even so, wildlife needs more green corridors that allow them to move through the territory.

Whenever a new transportation route is created, a key question arises: How will we respond to the fragmentation of space that this implies for people living on both sides of the territory? Although there are critical voices about the impact of these infrastructures in terms of noise levels or the destruction of territorial and social cohesion, work is being done on solutions such as underpasses or overpasses to alleviate the problem. But if humans have bridges and other tools, what about the animals that also live on either side of the space now intersected by a highway or high-speed rail?

For them, there are wildlife crossings. The Netherlands was the pioneer in creating these solutions, as Isabella Tree talks about in “Asilvestrados” (Captain Swing). “The Netherlands took the lead with the construction of green bridges, with more than sixty-two ecoducts built since 1988,” Tree notes in her book.

These green bridges were not intended for humans, but for nature itself. They were a way to give wildlife the tools to continue circulating in the territory without being exposed to the dangers of road traffic. The first of the Dutch ecoducts was planted with trees and in six years managed to become the pathway that many species used to move from one side to the other. In another, Tree notes, there are even “a series of amphibian access ponds and ramps.”

“This step is the measure to be applied in each infrastructure to minimize impact,” explains Luis Suárez, WWF Spain's Conservation Coordinator. In Spain, as Suárez points out, there are underpasses, which must respect minimum measures and certain conditions to allow animals to use them without issue, and those that are like bridges for nature, precisely what are known as ecoducts.

Ecoducts are not like pedestrian walkways, but are integrated into nature. What is interesting is that these proposals serve to allow animals to continue to move around, but also have a direct effect in neutralizing some of the risks to which they are exposed. Tree recalls how in Sweden ecoducts are used to reduce traffic accidents caused by moose and roe deer, which thanks to these infrastructures do not cross the road, and thus do not walk between cars; but other examples can also be found closer geographically. For example, they have played a role in preventing accidents affecting lynxes, a protected species in Spain.

As Suárez acknowledges, in places where there are “outstanding species” (those that the media and conservation organizations always end up paying more attention to), these steps have had a more established trajectory. This is the case in the Cantabria region with bears, or in Doñana, where much more can still be done to protect animals but where wildlife crossings have already achieved good success rates, as in the case of the lynx. “Doñana is a good example,” says the expert, because “blind spots” were detected and solutions were designed to prevent roads from killing wildlife in this protected environment.

In fact, it is data like this that confirms their potential. As Suárez points out, “if they are well designed,” they can be useful in reducing the impact on the environment and preserving the fauna in the areas where these transport routes have an impact.

But how to make them so that they are actually functional for the species and help reduce the impact of transport? To begin with, the question should be asked about the routes themselves. In a country where there is already a dense road infrastructure, Suárez points out that the first step is to “think very carefully about whether it is necessary when we are going to build a new infrastructure.”

If the step to construction is taken (or if we remember that the Spanish road network is made up not only of new roads, but also of much older ones developed when this was not taken into account), it is not enough to simply create ecoducts or underpasses for animals. Building a green bridge at a certain spot is not enough. It is necessary to understand what species live in that area, what their needs are and, above all, what their traditional pathways have been. This information is not difficult to obtain, as the expert points out, and allows the best decisions to be made, “depending on the type of species, to see which design best fits the layout.” Likewise, adding other deterrents, such as fencing, to bring wildlife in a somewhat organic way to these crossing points may help to encourage their use.

And, of course, despite all this, it is also crucial that when driving and you see signs warning of the possibility of wild animals on the road, you take them into account. We should not, the expert reminds us, undervalue them. Not only do they help reduce danger to drivers, but also to the species of animals that may come onto the road.

More highways for animals

Spain is the country contributing the largest amount of its territory to the European Natura 2000 Network. 27% of the Spanish territory is part of the network. And yet, its animal inhabitants face serious problems. There has been a 50% drop in the number of wild mammals living there and these natural areas are exposed to increasing fragmentation, as pointed out a couple of years ago in WWF's “Wild Animals” report.

Species have become increasingly isolated in their territories, spaces that are increasingly enclosed by transport networks or agriculture, and are also threatened by the effects of climate change. In doing so, not only is the biodiversity of each of these areas at risk, but animals also face an increased need for mobility. But, for the animal inhabitants of these spaces spread out throughout the territory, traveling from one to another is not easy. In some areas, Suárez points out, there are “bottlenecks”, since the spaces for the animals to pass through are only very specific points in the geography.

What the organization recommends is the creation of “wild highways”: twelve ecological corridors that ensure connectivity between these natural spaces, allowing these animals to move around. It is feasible and achievable, they say, and would not only meet the current needs of the Iberian fauna, but also the challenges of the very near future. “Not only is it something that wildlife already needs, but with climate change they will have to migrate more,” Suarez points out.