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Surprising number of hyenas are killed by vehicles every year

A team of scientists from the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) conducted a 34-year study on the factors contributing to fatal collisions between vehicles and spotted hyenas in the Serengeti National Park, Tanzania. 

Although driving is permitted in the protected area, many wild animals, including spotted hyenas, are killed by vehicles, leading to negative impacts on wildlife.

The study identified two main factors that significantly contribute to spotted hyenas being run over by vehicles. Firstly, the characteristics of the road, and secondly, the annual migration of the large ungulate herds in the Serengeti, which causes seasonal changes in the prey animals’ localization. 

The findings provide new insights into the ecological and individual factors that affect predators’ risk of fatal collisions with vehicles. The study was published in the scientific journal Biological Conservation.

The researchers found a total of 104 spotted hyenas that had been run over between 1989 and 2023. Based on these cases, they investigated which spatial and temporal factors contribute to spotted hyenas being run over and killed by vehicles, as well as whether specific age groups, sexes, or social statuses are more vulnerable. Long-term studies of this nature are rare.

The Serengeti National Park has a network of roads that includes main gravel roads, which are used by tourist vehicles, park staff, trucks, supply vehicles, and national bus lines throughout the year. 

Additionally, there are several unpaved wildlife observation and camp access tracks. Human populations on the borders of protected areas and the growing interest in wildlife tourism are causing the negative impacts of roads on wildlife to increase worldwide.

In general, two factors played a crucial role. The first factor was that hyenas were more frequently hit by vehicles on primary roads rather than on “tracks.” This was likely due to the higher volume of traffic and faster speeds on main roads. The second factor was the seasonal migration of large herds of ungulates (such as wildebeest, zebra, and Thomson’s gazelles), which are the primary prey of Serengeti spotted hyenas. The timing and location of fatal collisions varied with the migration of these herds.

These findings align with previous studies that demonstrate a higher risk of animal-vehicle collisions with increased animal mobility and distance traveled. Furthermore, the hyenas that were killed tended to be located near watercourses and human habitation areas, which may attract them due to 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 this project and is the lead author of the publication.

The dataset utilized in this study is unique in that it includes information on individual hyenas that were hit by vehicles, allowing the researchers to consider various factors of their life history during analysis. Results indicate that adult females were the most frequent victims, likely due to their need to travel long distances between their den and prey herds, balancing hunting and nursing responsibilities.

“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, roadkills 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 local spotted hyena population.

In the Serengeti, road networks are expected to expand in the future, even within protected areas. Understanding the factors that contribute to fatal collisions between vehicles and wildlife, such as road features, can aid in the development of effective mitigation measures. 

These measures may include reducing the number and speed of vehicles on major roads. Proper planning and implementation of mitigation measures will be crucial for the preservation of wildlife in protected areas.

More about hyenas

Hyenas are fascinating animals that have long been misunderstood and unfairly maligned. These carnivorous creatures are found throughout Africa and parts of Asia, and they play an important role in their ecosystems. In this article, we’ll take a closer look at hyenas, their behavior, and their place in the natural world.

Firstly, it’s important to dispel some of the myths and misconceptions surrounding hyenas. For many years, these animals have been portrayed as vicious, cowardly scavengers that are only interested in stealing food from other predators. In reality, hyenas are powerful hunters that are more than capable of taking down their own prey. They are also highly social animals that live in large groups called clans, which can consist of up to 80 individuals.

There are four species of hyena: the spotted hyena, the brown hyena, the striped hyena, and the aardwolf. The spotted hyena is by far the most well-known and widely studied species. They are easily recognized by their distinctive spotted coat and powerful jaws, which are capable of crushing bone. Spotted hyenas are found throughout sub-Saharan Africa, and they are often seen in savannah and grassland habitats.

Hyenas are primarily nocturnal, and they spend much of their day resting in dens or in the shade. At night, they become much more active, and they may travel long distances in search of prey. Hyenas are opportunistic hunters that will eat almost anything they can catch, including antelopes, zebras, wildebeest, and even smaller predators like jackals and foxes. They are also known to scavenge from the kills of other predators, but this is only a small part of their diet.

One of the most interesting aspects of hyena behavior is their dominance hierarchy. Within a clan, there is a strict pecking order based on size, strength, and aggression. Female hyenas are generally larger and more dominant than males, and they are the ones that do most of the hunting. When a kill is made, the females eat first, followed by the cubs and lower-ranking members of the clan. The males are the last to eat, and they often have to wait until the females have finished before they get a chance to feed.

Despite their fearsome reputation, hyenas are actually very intelligent and social animals. They communicate with each other using a variety of vocalizations, including whoops, growls, and giggles. They also have a complex system of body language, which they use to signal dominance, submission, and aggression. Within a clan, there is a strong sense of cooperation and kinship, and the members of the clan will often work together to defend their territory and protect their young.

In summary, hyenas are fascinating animals that play an important role in their ecosystems. They are powerful hunters that are capable of taking down large prey, and they are also highly social animals that live in large clans. While they have been unfairly maligned in popular culture, hyenas are actually intelligent and fascinating creatures that are well worth studying and understanding.


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