SAVING SPOTS AND STRIPES
Road infrastructure is a common feature wherever humans have settled. South Africa is rated as the 25th largest country in the world and ranked 18th in relation to the total road length (65,600 km paved, 689,000 km unpaved) and 74th in the total number of cars per 1,000 people. Roads are critical in providing access to primary health care, education, markets, and employment, ultimately improving livelihoods.
However, South Africa is the third most biologically diverse country in the world, and it is increasingly clear that roads and road users affect the functioning of ecosystems in which they occur. Direct collisions with wildlife have the most obvious impact, but the indirect disruption of ecological processes is equally important. Habitat loss, degradation, and population fragmentation, and disruption of the processes that maintain regional populations are just some of the ways roads can affect biodiversity.
Development is taking place rapidly, with new roads and housing developments mushrooming and trans-continental rail and road developments being expedited. In the past, such developments were planned without much thought to their impact on biodiversity, but the EWT has been working hard to improve road-user safety – that of both the occupants of vehicles and the wildlife living adjacent to or crossing our roads. We’ve been collecting data in a variety of ways, including the use of citizen scientists (data submissions from the general public), planned surveys and, importantly, using the road patrollers that drive our highways daily to deal with any hazard they come across, including the removal of dead animals from the road.
The EWT analyses roadkill data regularly, and one of the species that has caught our attention is the Serval. This mostly solitary, nocturnal species was considered extinct, or near-extinct, in the latter half of the 20th century, largely due to the mistaken belief that it caused damage to agricultural crops and compounded by competition from other carnivores such as jackal. Reintroductions and range expansions have led this species to recover to an estimated adult population of somewhere between 4,509 and 13,654 individuals, but the population is again considered to be declining due to a loss of its wetland habitat.
Serval (Leptailurus serval)
Servals are predominantly solitary except when mating or before young would leave their mothers at around eight months old. Like Leopards, the young females form territories adjacent to that of their mother, with males having larger territories that overlap that of several females.
The N3 Toll Concession, which manages the 412 km stretch of road from Heidelburg (Gauteng) to Cedara (KwaZulu-Natal), has been extremely supportive of our efforts to mitigate roadkill along the Toll Route and is concerned about the safety of both the road users and the wildlife living alongside the road.
In addition to our usual reports to the N3 Toll Concession, the EWT has been looking into why the Serval is one of the most common species reported (Figure 2) and why their roadkill numbers show an upward trend.
We plotted the location of the roadkill along the N3 and noted that although roadkills were spread along the length of the road, there was a cluster along the northern parts of the route. This area is predominantly highveld sourveld and is either farmed for cattle or game or planted with mielies.
We also looked at the proximity of water to the road. Servals are wetland specialists, which are likely to be clustered close to water bodies. Water is spread fairly evenly across the landscape, and where perennial rivers are not available, farmers have created artificial water points for livestock and/or game. The diet of Servals consists mainly of Vlei Rats, so the abundance of water along the N3 does create the ideal habitat for them.
Our work is still in its infancy, and we plan to keep investigating the drivers of roadkill for this species by investigating the following:
- Whether Serval prefer artificial or natural water bodies;
- The abundance of prey species;
- Whether or not Serval use underpasses (tunnels and culverts) to cross the road; and
- If the Serval being killed on the road are young dispersing males or breeding adults, and the impact of this on the local and broader population.
Thank you to the N3 Toll Concession for their ongoing support of our work and Ford Wildlife Foundation for keeping us on the road.
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