Despite expanding road networks, there is limited understanding of the effects of roads on wildlife in East Africa. We present a baseline survey and describe the patterns of roadkill in the Tarangire–Manyara ecosystem of Tanzania. A 75 km stretch of the Arusha Highway that passes adjacent to Manyara Ranch and Lake Manyara National Park was studied for 10 consecutive days in November 2013 (the rainy season). Wildlife species killed on the road, roadkill frequency and road characteristics were determined. A total of 101 roadkill were recorded (0.13 roadkill km⁻¹) comprising 37 species from all terrestrial vertebrate groups, of which two species, house cat (Felis catus) and domestic dog (Canis lupus), were domesticated species. Birds were the most frequently killed taxon (50%), followed by mammals (30%), reptiles (17%) and amphibians (3%). Excluding birds, roadkill primarily consisted of nocturnal species (65%) versus diurnal species (35%). Most roadkill (77.3%) were encountered on road stretches adjacent to protected areas of Manyara Ranch and Lake Manyara National Park compared with 22.7% on the road stretches adjacent to non-protected areas. These findings highlight that roads are a potential threat to wildlife in East Africa and serve as a baseline for future comparisons.

Previous assessments of wildlife road mortality have not used directly comparable methods and, at present, there is no standardized protocol for the collection of such data. Consequently, there are no internationally comparative statistics documenting roadkill rates. In this study, we used a combination of experimental trials and road transects to design a standardized protocol to assess roadkill rates on both paved and unpaved roads. Simulated roadkill were positioned over a 1 km distance, and trials were conducted at eight different speeds (20–100 km·h⁻¹). The recommended protocol was then tested on a 100‐km transect, driven daily over a 40‐day period. This recorded 413 vertebrate roadkill, comprising 106 species. We recommend the protocol be adopted for future road ecology studies to enable robust statistical comparisons between studies.

Roads impact wildlife through a range of mechanisms from habitat loss and decreased landscape connectivity to direct mortality through wildlife-vehicle collisions (roadkill). These collisions have been rated amongst the highest modern risks to wildlife. With the development of “citizen science” projects, in which members of the public participate in data collection, it is now possible to monitor the impacts of roads over scales far beyond the limit of traditional studies. However, the reliability of data provided by citizen scientists for roadkill studies remains largely untested. This study used a dataset of 2,666 roadkill reports on national and regional roads in South Africa (total length ~170,000 km) over 3 years. We first compared roadkill data collected from trained road patrols operating on a major highway with data submitted by citizen scientists on the same road section (431 km). We found that despite minor differences, the broad spatial and taxonomic patterns were similar between trained reporters and untrained citizen scientists. We then compared data provided by two groups of citizen scientists across South Africa: (1) those working in the zoology/conservation sector (that we have termed “regular observers,” whose reports were considered to be more accurate due to their knowledge and experience), and (2) occasional observers, whose reports required verification by an expert. Again, there were few differences between the type of roadkill report provided by regular and occasional reporters; both types identified the same area (or cluster) where roadkill was reported most frequently. However, occasional observers tended to report charismatic and easily identifiable species more often than road patrols or regular observers. We conclude that citizen scientists can provide reliable data for roadkill studies when it comes to identifying general patterns and high-risk areas. Thus, citizen science has the potential to be a valuable tool for identifying potential roadkill hotspots and at-risk species across large spatial and temporal scales that are otherwise impractical and expensive when using standard data collection methodologies. This tool allows researchers to extract data and focus their efforts on potential areas and species of concern, with the ultimate goal of implementing effective roadkill-reduction measures.

Social media discussions highlight public concern for wildlife‐vehicle collisions (WVCs) inside protected areas. Using a quasi‐experimental field trial, we investigated factors affecting the likelihood of WVCs within Pilanesberg National Park, South Africa, and assessed the comparative effectiveness of wildlife‐warning signage (WWS) for altering driver behaviour. We laid a dummy snake crosswise on roads across four combinations of habitat and road shape and recorded 10 driver‐related variables for 1454 vehicles that passed the dummy snake, including whether there was a collision. An interaction between speeding and driver occupation (staff/visitor) was the best indicator for WVC. When driving below the speed limit, visitors were almost three times more likely than staff to hit the dummy snake. Collision probabilities increased when speeding and became more similar between visitors and staff, although still significantly higher for visitors. We then investigated the effectiveness of roadside signage in modifying driver behaviour by erecting four variations of WWS, depicting a snake or a cheetah, and in photographic or silhouette form. We positioned the dummy snake 100 m or 1 km after the signage and recorded our 10 variables (n = 6400 vehicles). Sixty‐one per cent of drivers who passed a WWS changed their behaviour when they saw the dummy snake, compared to 37% with no sign present. Further, this behaviour change significantly reduced collisions, where 98% of drivers who changed their behaviour avoided a collision. Finally, an interaction between the animal depicted and distance before the dummy snake affected collisions. A WWS depicting a snake, and placed 100 m before the dummy snake, was most effective at reducing collisions. Our results suggest that drivers adapt their behaviour to signage that portrays smaller animals and awareness retention is low. Ultimately, to reduce WVCs within protected areas, we suggest steeper penalties for speeding and WWS placed in WVC hotpot areas.

Using a standard protocol, we conducted vertebrate roadkill surveys in the Greater Mapungubwe Transfrontier Conservation Area (GMTFCA), South Africa, which is a World Heritage Site. A total of 991 roadkill were recorded on the paved roads and 36 roadkill on the unpaved roads. Identifiable roadkill comprised 162 species from 24 orders and 65 families. Ninety-three roadkill could not be identified to species level. Roadkill counts were strongly influenced by road type and season. More roadkill was recorded on the paved than the unpaved roads. Irrespective of road type, the proportion of roadkill was greatest in the hot/wet season (4.3 paved roadkill/km/day paved and 1.3 roadkill/km/day unpaved) and lowest in the cold/dry season (2.0 roadkill/km/day paved and 0.1 roadkill/km/day unpaved). The high numbers of vertebrates identified as roadkill suggests that road traffic has the potential to directly and negatively affect biodiversity conservation in this part of South Africa. We recommend continued roadkill d...

As the global road network expands, roads pose an emerging threat to wildlife populations. One way in which roads can affect wildlife is wildlife-vehicle collisions, which can be a significant cause of mortality through roadkill. In order to successfully mitigate these problems, it is vital to understand the factors that can explain the distribution of roadkill. Collecting the data required to enable this can be expensive and time consuming, but there is significant potential in partnering with organisations that conduct existing road patrols to obtain the necessary data. We assessed the feasibility of using roadkill data collected daily between 2014 and 2017 by road patrol staff from a private road agency on a 410 km length of the N3 road in South Africa. We modelled the relationship between a set of environmental and anthropogenic variables on the number of roadkill carcasses, using serval (Leptailurus serval) as a model species. We recorded 5.24 serval roadkill carcasses/100 km/year. The number of carcasses was related to season, the amount of wetland, and NDVI, but was not related to any of the anthropogenic variables we included. This suggests that roadkill patterns may differ greatly depending on the ecology of species of interest, but targeting mitigation measures where roads pass through wetlands may help to reduce serval roadkill. Partnering with road agencies for data collection offers powerful opportunities to identify factors related to roadkill distribution and reduce the threats posed by roads to wildlife.