The spectacular wildebeest migration in the Serengeti National Park has been found to claim the lives of at least five spotted hyenas every year.
Unlike in the Lion King where a confusion of wildebeests trample the large cat to death, the case of spotted hyenas in the Serengeti, is quite different, the carnivores get run over by vehicles as they chase after the ungulate for their food.
It took scientists 34 years to study the trend which revealed that five, mostly female spotted hyenas, get killed by speeding vehicles in the plains, mostly while chasing the ungulates that form the Serengeti migration annually.
As part of the long-term study in the Serengeti, the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) scientists documented that a total of 104 spotted hyenas have been run over in the period between 1989 and 2023.
Based on these cases, they investigated the question of which spatial and temporal factors particularly contribute to spotted hyenas being run over and killed by vehicles, and whether spotted hyenas of one age group, sex or social status are particularly affected.
Overall, two factors proved to be crucial.
Firstly, hyenas were more often run over on main roads than on ‘tracks,’ probably because there is more traffic on main roads and vehicles travel faster there.
Secondly, the timing and location of fatal collisions varied with the seasonal migration of the large herds of ungulates, including wildebeest, zebra and Thomson’s gazelles, which are the main prey of the spotted hyenas in Serengeti.
The results are consistent with other studies showing that the risk of being killed by a vehicle increases with the mobility and distance travelled by the animals.
In addition, killed hyenas were found particularly close to watercourses, human dwellings, possibly hotels and lodges, to which the hyenas are presumably attracted by the presence of human food waste.
“Contrary to expectations, the seasonal variation in the number of tourists in the region did not seem to play a role in the level of mortality,” says Marwan Naciri, who joined the Leibniz-IZW for the project.
Naciri is also the lead author of the report publication.
Serengeti National Park is home to large populations of wildlife species, including the spotted hyenas (Crocuta ocaliz).
A special feature of the dataset used in this study is that some of the hyenas that were run over were individually known and therefore factors of their life history could be included in the analysis.
For example, the analyses show that adult females were most frequently run over, probably because they are the ones who regularly have to travel long distances between their den and migrating prey herds in order to be able to hunt on the one hand and nurse their cubs left at the den on the other.
“Injuries from illegally laid wire snares also particularly affect adult female hyenas, as we found in a previous study,” says Leibniz-IZW scientist Sarah Benhaiem, involved in both research projects.
In summary, road kills and death by snares could be one of the main causes of death for adult hyenas in the Serengeti.
It is still unclear whether this mortality, which mainly affects adult females, threatens the continued existence of the spotted hyena population in the Serengeti.
Even in protected areas, many wild animals are killed by vehicles worldwide, and these negative impacts of roads continue to increase due to the rise of human populations on the borders of protected areas and the growing interest in wildlife tourism.
However, according to the report, the factors that contribute to fatal collisions between vehicles and wildlife are still poorly understood.
While many human activities are prohibited in the national park, driving is allowed in and through the protected area.
Using a 34-year long-term data set, a scientific team from the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) analysed which factors contribute significantly to hyenas being run over and killed by vehicles.
The results of the analyses indicate that mainly two factors play a role: firstly, the characteristics of the road and secondly, the annual migration of the large ungulate herds in the Serengeti and the associated seasonal changes in the localization of the prey animals of the spotted hyenas.
These findings provide new insights into which ecological and individual factors influence predators’ risk of fatal collisions with vehicles and were published in Biological Conservation.