Habitat and General Information about the Wildebeest
General Wildebeest Information
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The wildebeest is simply an absurd looking animal. Some people even go so far as suggest that the wildebeest looks "rather like a four-footed ballet dancer" (Street, 1963). Males and females both have short horns that grow outward with curvy ends (Moss, 1975). The eyes of the wildebeest are far apart and high up on the head. This placement gives the wildebeest a seemingly solemn or surprised look at all times. A wildebeest stands approximately four to four and a half feet, when measured at the shoulder. Males weigh about 400 - 500 pounds, and females weigh about 300 - 400 pounds. The upper body of the wildebeest including the shoulders and neck are well developed and rather large. However, the rear of the wildebeest body slopes downward and appears weak (Moss, 1975). |
This disproportional body combined with the skinny little legs on which the wildebeest stands not only give the wildebeest a very unique appearance, but also make the wildebeest running style seem quite funny. In motion, the wildebeest possesses a jerky gait that looks somewhat mechanical. Moss describes the wildebeest's running motion by saying that "the whole effect is that of a wind-up toy." Because of the bizarre cavorting actions that the wildebeest makes when excited, they are often termed "the clowns of the veld" (Moss, 1975).
Habitat
The continent of Africa is home to almost all of the world's wildebeests, and throughout Africa two species of wildebeests reside (Moss, 1975). The black wildebeest, also known as the white-tailed gnu, resides primarily in South Africa. The blue wildebeest, also known as the brindled or white-bearded gnu, lives from parts of southern Africa through southern Kenya. The greatest number of wildebeests are located in northern Tanzania and southern Kenya in national parks such as the Maasai Mara Game Reserve, Serengeti National Park, and the Ngorongoro Conservation Area (Moss 1975).
The wildebeest lives out in the open plains, and feeds exclusively on grasses. This member of the antelope family is dependent upon water for drinking (as opposed to the Dik Dik and gerenuk, which are water-independent) (Estes, 1975), and is confined to a measured grazing radius of 15 km from a source of drinking water (Berry, 1982). As described below, the wildebeests migrate annually in search of water within their environment, which is predominated by short, unreliable wet seasons and grass high in crude fiber content (Berry, 1982). In addition to migration, the following six characteristics have allowed the wildebeest to thrive in this environment (1) A rumen, which provides an environment for symbiotic microflora to convert cellulose to protein and carbohydrates, (2) a mouth morphology suited for rapid ingestion of grass, which acts as an anti-predator tactic, (3) an adaptive leg morphology, which also acts as an anti-predator device, (4) inward-curving horns, which aid in balance and are used in predator attacks, (5) a large body, which supports long distance migrations, (6) a highly developed neocortex in the brain, which gives the wildebeest a tendency to graze rather than browse and is correlated with social organization (Berry, 1982).
As a personal witness of its beauty, I believe that the wildebeest migration is perhaps one of the world's most beautiful sites to behold. Every year migratory wildebeests move over an area that extends from the Ngorongoro Crater in the east of Africa to Lake Victoria in the western region, and from Lake Lagarja in the south to the Maasai Mara Game Reserve in southern Kenya (Estes, 1979). In total, the wildebeests cover about 12,000 square miles. Contrary to long held beliefs, the wildebeests take different routes throughout this area each year, and no two migrations ever have the same pattern. (Estes, 1979). Patterns of migration may take on slightly different shapes each year in response to the rainfall (Gnu, 1968). For example, herds of wildebeests may migrate towards storm clouds that are more than 80 km away (Gnu, 1968). Routes are generally very circuitous and involve much doubling-back and circling around (Estes, 1975).
The driving force behind the year's pattern is rainfall (Estes, 1975). The wildebeest has an incredibly acute sense of when and where rain will fall and plan their paths so that they may have plenty of water for drinking. Wildebeests are usually found out on the short grass plains in the east during January. Near the end of May, most of the grass on the short grass plains becomes dried up and water is hard to find. Thus the wildebeests move off the plains and into the woodlands, which are located further north and west. Although wildebeests move year-round, the movement around the month of May is the most conspicuous and may often be referred to as "the great migration." In June most of the wildebeests move west and end up near Kenya in search of water. In November and December, the wildebeests go south, where the rain has usually begun to fall. However, the pull towards the southern plains is not completely understood since rainfall can also be found in the north and west (Estes, 1975).
In order to increase the success of their migration, wildebeests leave a strong scent along the trail (Maier, 1998). This mechanism allows individuals who become separated from the group to rediscover the group's whereabouts (Maier, 1998). Migratory males are still able to set up temporary territories in which mating can occur. These territories are defended just as a sedentary, permanent territory, is defended (Gnu, 1968).
Are the Migrators More Abundant?
Research by Fryxell et al. (1988) examined the factors regulating the abundance of the Serengeti wildebeests. They considered three hypotheses: (a) migrants may have greater access to food since the utilize a larger area, (b) migrants may make better use of the available resources, and (c) migrants may be less vulnerable to predation since a predator may be unable to follow a migrating herd (Fryxell et al., 1988). These hypotheses were tested using a simulation model for the wildebeest population. Results showed that a larger area does not necessarily lead to larger population numbers. Similarly, even migrants with greater access to food during certain periods of the year will not increase in abundance if the amount of food is the same during the leanest periods for both migrants and sedentary populations of wildebeest. In response to the second hypothesis, the researchers found that while rotational grazing could increase efficiency and thus numbers of wildebeests, this type a system is unlikely for the savanna ecosystems in Africa due to the quality of the grasses and their seasonality. Thus, Fryxell et al. concluded that realistic numbers of predators could regulate sedentary wildebeests at low population densities. However migratory herds are most likely not subject to this predation regulation. They predict that when sedentary and migratory wildebeests have overlapping grazing areas, migrants should outcompete resident wildebeests (Fryxell et al., 1988).
The Wildebeest and Its Neighbors
The wildebeests share their habitat with many other animals on the plains. In a study by Boer et al. (1990), research indicated that habitat overlap between the zebra and the wildebeest is significantly high. Data also showed that the presence/absence of the buffalo did not influence the size of the wildebeest herd, nor did the size of the wildebeest herd affect the size of the buffalo group. In fact, Boer et al. (1990) found that wildebeests and buffalo appeared to seek each other's company. The size of zebra herds, however, was affected by the presence of the wildebeest. Zebra groups were significantly larger (28 individuals) when in the presence of a wildebeest herd than in their absence (16 individuals). This change in population size occurred when the animals were grazing upon C. dactylon, but did not occur when S. spicatus served as the vegetation. Boer et al. also investigated grazing pressure and found that the amount of wildebeest grazing pressure was positively affected by the amount of zebra grazing (Boer et al., 1990).
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