Impalas on the road


There are papers of which I am particularly proud because of how much I learned working on them or because I believe they represent (more) important contributions to the literature. Then there are papers that were just lots of fun to do. My most recent publication falls into this last category for several reasons. First, I worked with my good friends Mara Mulero and Marcello D’Amico. We are the “equipo MA”, and you know you are having fun when you give yourself a nickname! Second, we worked in the amazing Kruger National Park, a place bursting with the type of wildlife one sees in nature documentaries. It was also my first time in Sub-Saharan Africa, and Africa has captivated me. Third, this study meant a come-back to field research for me, something I missed during my postdoc years and, which brought me back to more tangible, local-scale, conservation problems.

Roads are found almost everywhere in the planet. And we are building more and more. Many of these roads link cities or towns but in many National Parks or protected areas in Africa these roads are actually a way to facilitate tourism. When lions roam free, walking around to see wildlife can be a risky business, so most tourists in open-habitat African parks use motorized vehicles to enjoy nature. Tourism can be a good thing for conservation as it provides an economic reason to preserve natural areas and wildlife. But when tourism means roads, one needs to think about how this is impacting the natural areas and wildlife we seek to protect. Our study is a just a small contribution to the road ecology literature that seeks to understand exactly that issue: the interactions between road systems and the natural environment.

We studied a common ungulate (hoofed mammal) species, the impala Aepyceros melampus. We determine how often impala that are near roads run away when a vehicle passes by. This is called a flight response: an escape reaction to a potential danger. We found that impala rarely ran away, suggesting these animals may no longer scared of vehicles. This may not be surprising as Kruger National Park was founded 90 years ago and currently receives over 1.6 million visitors per year (that is a lot of cars!). Because impala are not shot within the park, except with cameras, animals may have learned that vehicles do not represent much danger and so they continue to eat and rest when a car drives by. However, we did find that impala tend to avoid the close proximity of well-traveled paved roads. Although cars may not be dangerous lots of traffic can be bothersome. In some areas we counted >1 vehicle per minute; sometimes it felt like rush hour in the main roads! So impala may not be threatened by vehicle presence but probably do not like the noise and disturbance cars represent, so their distribution in relation to the road, how far they stay eating and resting, which we measured as tolerance distance,  is affected by roads and traffic.


While this is a relatively small study looking at a single species, our work suggests that we need to be careful about how we build roads and manage traffic within protected areas. Limiting the number of visitors, redirecting traffic, encouraging group visits (fewer vehicles for the same number of tourists), and avoiding road development in some areas are all potential solutions. We all want to see the most amazing animals but sometimes they would rather not see us.

UPDATE from 29 June 2017: The Journal of Zoology published a commentary on this paper and our reply. Email me for copies if you cannot access these.



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