Wildebeest That Don’t Migrate

The sun was beginning to set. We were heading back to the camp when we came across two antelope seemingly challenging each other.

These were two Blue Wildebeest (Connochaetes taurinus). This is a larger species of antelope, weighing up to 522 lbs. (237 kg). This species has a broad muzzle with flexible lips to help it eat grass. It has unringed horns that are hooked sideways, with knobby bosses. The animal’s coat is short and glossy, with a mane, beard, and facial tufts¹.

This species can be found in the savannas of eastern and southern Africa. The northern limit is in central Kenya, with the Orange River of South Africa marking its southern boundary¹.

This animal is known for its massive migration that it does in the Serengeti ecosystem of northern Tanzania and southwestern Kenya. I do want to walk about that, but that won’t be the focus of this post.

Instead, I want to focus on the individuals who don’t migrate.

While doing research for this post, I came across an interesting fact: there are populations of wildebeest that don’t migrate. Within the Serengeti ecosystem, there are three resident populations. One of these is found within the Masai Mara¹.

The social structures of resident populations are set up differently from the migratory population. In the latter, males and females move in large groups. The bulls defend temporary territories that they claim whenever the population comes to a standstill. These bulls create “herds” of females and young while cutting out non-competing males¹.

In the former, there is a network of territorial males. The males are defending their territory from other males. This network encompasses an area that is occupied by females. These live in small herds. These small herds live on a home range that includes a number of the male’s territories. Noncompeting males live on the periphery of the territories, usually in substandard areas, where they associate in bachelor herds¹.

The Masai Mara did have a migratory population, that traveled from the Loita Plains in the rainy season to the Masai Mara Reserve in the dry season. This is a distance of 90 miles (135 km)¹.

Unfortunately, this population has witnessed drastic declines. In the 1970s, the Mara population numbered over 100,000 wildebeests^1,2,3. By the 1990s, there were fewer than 50,000 animals², with about 22,000 wildebeest in 1997³. This is a decline of 81% of the population³. The migratory Mara population may have been eliminated¹.  

What was the cause of this decline? While fluctuations in rainfall and competition with cattle may have affected the population, these don’t appear to be the main drivers. The main driver appears to be the loss of its wet season grazing areas, where it also calved and bred. This territory has been lost to agriculture³.

This population of wildebeest finds itself living in more frequent contact with people. The way these grazers interact with people is interesting. Wildebeests tend to select areas that are further from roads and from dense woody vegetation. Distance from roads keeps them safe from traffic. Distance from stands of woody vegetation keeps them safe from potential predators⁴.

During the day, the wildebeest selected areas that were further from people. At night, however, they came in closer to people. This is likely due to human settlements providing protection from night-hunting predators. There may also be increased vegetation quality due to nutrient inputs from the livestock. During the day, pastoralists push wildebeest away from their settlements to minimize the threat of disease transmission from the wildebeest⁴.

It was intriguing to learn that an animal known for its migration could also live in areas where it doesn’t migrate. Unfortunately, this population has experienced a massive decrease in numbers, but hopefully, it can continue to coexist with people so that we don’t lose these resident populations of wildebeest.

As we continued our drive to the camp, I turned around, and the two animals continue their challenges as the darkness fell around them.

If you want to read about how wildebeest and other grazers coexist on the African savanna, click here!

If you want to read about another African mammal undergoing a population decline, click here!

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Estes, Richard D. “The Gnu’s World: Serengeti Wildebeest Ecology and Life History.” Berkely and Los Angeles: University of California Press, 2014 ¹

Said, Mohammed Y., Andrew K. Skidmore, Jan de Leauw, and Herbert HT Prins. 2003. Declining population of wild ungulates in the Masai Mara ecosystem: a sign of resource competition. Multiscale perspectives of species richness in East Africa (pp. 151-171). Wageningen University ²

Ottichilo, W. K., J. de Leeuw, and H. H. Prins. 2001. Population trends of resident wildebeest [Connochaetes taurinus hecki (Neumann)] and factors influencing them in the Masai Mara ecosystem, Kenya. Biological Conservation 97:271–282. ³

Stabach, J.A., G. Wittemyer, R.B. Boone, R.S. Reid, and J.S. Worden. 2016. Variation in habitat selection by white-bearded wildebeest across different degrees of human disturbance. Ecosphere 7(8): 1-17 ⁴