Animals in mountainous areas around the world, in particular endangered, vulnerable, and near threatened mammals, are at risk of becoming roadkill as road networks expand further into these previously inaccessible terrains.

These mammals, which fall into the category of conservation risk according to the International Union for Conservation of Nature (IUCN) definitions, include African wild dogs (endangered), lions and leopards (both vulnerable), elephants (endangered), and honey badgers (NT – near threatened). Among the road-killed birds found in these areas are the hooded vulture (critically endangered) and the endangered steppe eagle.

This is according to Prof Aliza le Roux, Assistant Dean of the Faculty of Natural and Agricultural Sciences and Professor in the Department of Zoology and Entomology, who presented research during a session at the Southern African Mountain Conference (SAMC2025). Prof Le Roux, a behavioural ecologist studying how animals respond to risks and opportunities in the environment, did an oral presentation titled Patterns of wildlife-vehicle collision in montane environments during a session on Mountain biodiversity: animals.

The conference, under the patronage of UNESCO and organised by the University of the Free State (UFS) Afromontane Research Unit (ARU) – in partnership with the African Mountain Research Foundation (AMRF) and the Global Mountain Safeguard Research Programme (GLOMOS) – brought together researchers, policy makers, and practitioners from across Southern Africa and beyond. It delved into critical issues around mountain ecosystems, communities, governance, and transboundary cooperation.

For the research, Prof Le Roux, Dr Katlego Mashiane, Lecturer in the UFS Department of Geography, and Dr Clara Grilo from the BIOPOLIS project in Portugal, looked for published data/papers from 1971 to 2024, finding that most of the published literature on roadkill in Africa came from the 21st Century.

Heightens risks to wildlife

According to her, they found that amphibians were killed at the highest rate in the mountainous regions, while mammals were killed most frequently in the low-lying regions. Mammalian species classified as near threatened or more vulnerable to extinction on the IUCN Red List were most frequently found in the high-elevation mountains (7,7% of species killed in these areas), but also in low-lying areas (3,8% of mammalian roadkill). About 3% of the birds killed at moderate elevations were also of conservation concern.

“Increased vehicular traffic and better-paved roads in montane environments heighten the risks to wildlife inhabiting these regions, including the potential for more wildlife-vehicle collisions, leading to higher mortality rates. In terms of sheer numbers, many more small species (less than 1 kg in adult weight) are killed than larger species. This is probably because we either don’t see them or don’t care if we hit them. But we do care if our cars collide with something large like an eland – it does damage to us as well as them.”

“Unpredictable weather patterns and sudden topographical changes all contribute to these roads potentially being more hazardous for both drivers and any surrounding wildlife: the ruggedness of these terrains and tortuosity of roads can make it harder for drivers and wild animals to detect one another on mountain roads, increasing the likelihood of collisions,” writes Prof Le Roux and her colleagues.

The researchers estimated the roadkill rates for each observed species and then analysed the correlation with topographic aspects of the study sites. They used the 90m digital elevation model downloaded from the geospatial cloud-computing platform Google Earth Engine and classified ‘high’ elevation mountains as regions lying above 2 000 metres above sea level (masl), ‘moderate’ elevation mountains as lying between 1 500 and 2 000 masl, and ‘low’ regions as areas below 1 500 masl.

Limited data

Prof Le Roux and Dr Mashiane also extracted slope and the topographic ruggedness index. Roadkill rates were estimated for 15 different amphibian species, 98 reptilian, 261 avian, and 273 mammalian species, comprising 5 549 individual road kills.

“These findings indicate that roads in mountainous African regions pose a high risk to our indigenous wildlife. The accidents in mountainous areas are something to be aware of, as we are moving further into mountains where there is often vulnerable and unique biodiversity. When we do kill vertebrates through a collision, it is often a species that we would not find in low-lying areas.”

Unfortunately, Prof Le Roux says, they cannot say what the continental patterns are because so little data is available about biodiversity and roadkill patterns in the central and western parts of the continent. The data they found came from only 10 countries, and almost none of the studies took the form of systematic, longitudinal monitoring. The data sets were all ‘snapshots’ of roadkill in specific areas.