How did the elephant cross the railway line?

By Hannah De Villiers

When I started my Masters in wildlife conservation and thought about what I would like to research, I didn’t really picture myself focusing on transportation infrastructure. Rather spending time in the bush with some of Africa’s beautiful wildlife species… right? But unfortunately, road and rail infrastructure are one of the largest drivers of habitat loss and fragmentation, and therefore biodiversity loss, worldwide. So, whilst it may not be the dreamiest of subjects…it is a topic of critical importance to saving our beautiful wildlife and wild places!

Elephants (Loxodonta africana)

Transport infrastructure plays a pivotal role in economic and social development through creating improved access to resources and associated livelihood provided. Railways are a critical component of sustainable transportation. They have many environmental and economic advantages over other forms of transport, seeing, therefore, a massive expansion globally. In Africa, more than 30 massive development corridors, including rail infrastructure, are planned or progressing. As a consequence, we are expecting the rail footprint on the continent to increase by 85% in the coming years. However, these corridors will pass through 400+ protected areas containing some of Earth’s most diverse and sensitive ecosystems.

Impalas (Aepyceros melampus)

In the Balule Nature Reserve, part of the 200 000 ha of Associated Private Nature Reserves (APNR – Timbavati, Klaserie, Umbabat, Thornybush, and Balule) that are open to Kruger Park, a 30 km stretch of railway line runs directly through the middle of the reserve. A railway line that is frequented by herds of Kruger’s elephant, buffalo, and impala. Where lion, leopard, and wild dog are often seen walking along it (and using it to hunt).

Elephants (Loxodonta africana)
Lion (Panthera leo)

As conservationists, we are concerned about two key ecological impacts of railways: the barrier effects and resultant habitat fragmentation it may cause for local wildlife populations, as well as the mortality it might cause through wildlife-train collisions. For some animals, the railway does not create a barrier in the landscape, and they often simply walk over it. But this means they are in danger of collisions with trains – which, unlike cars, cannot quickly slow down or swerve to avoid a collision. Over 500 wildlife-train collisions have been reported over the past 25 years in this reserve. They mostly affected buffalo, lion, impala, and giraffe. We think that perhaps many more collisions are going unreported. Other animals have been seen to simply avoid the railway line entirely – certain elephant groups and rhino individuals in particular.

Wild dogs (Lycaon pictus)

But what if animals could find a safe passage across the railway without the risk of collisions? A passage that would increase the permeability of the rail corridor and so improve habitat connectivity? Wildlife crossing structures provide just that! In addition, culverts or viaducts are a common design feature of all railways, typically built for drainage and topographical purposes. These pre-existing underpass structures can easily be modified to improve their use by wildlife. This ‘upgrade’ is regarded as the most economical and feasible form of mitigation for wildlife mortality and barrier effects. However, the economic advantages of this approach do not stop there. Train collisions with large mammals can be incredibly expensive, invariably damaging or derailing trains and often resulting in large-scale service disruptions.

The inside and entrance of a culvert.
Hannah for reference.

I am therefore starting to research the use of railway underpasses and drainage culverts by large mammals in the Balule Nature Reserve. To do it, I will be putting up camera traps at the underpass entrances to understand which species use them (or don’t use them). I will analyse how the structural dimensions, the nature of the habitat close to the structure, the surrounding landscape, and mammal characteristics affect their usage. The findings of this study will hopefully help inform the design of underpasses along new railways in the African context. They will also aid reserve management in feasible modifications to culverts along existing railways that would make them more attractive for large mammal use.

I look forward to updating you all with some special images from the camera traps in the next few months!