Herds of wildebeest traversing the Serengeti. Their physiology requires them to drink at least every other day, and this need is the basis for an incredibly well-developed sense of smell that allows them to detect water even when the savannah seems dry. The terrorised calf had no visible injuries and disappeared, still bleating, into the thicket in the same direction his herd had gone. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The wildebeest has long horns comeing out its front, and can easily defend off predators while the ostrich, zebra, and gazelles get away. Wildebeest and zebra numbers Population estimates of wildebeest and zebra were made from aerial counts conducted during winter and summer months from January 1986 until January 1990, as described by Joubert (1983). During December a lot of wildebeest calves are born and it is absolute mayhem at the waterholes. Zebra occur in stable family groups, comprising of one dominant male with several females and their associated young [40]. de Boer & Prins (1990) found a strong association between zebra and wildebeest. Zebra and wildebeest usually maintain a symbiotic relationship, eating different the parts of the same plants in the savanna and are often seen living happily together. Mean annual rainfall is 515 mm (±70 SE), but animals have access to natural rivers and artificial waterholes throughout the year. This difference in physiological constraints may explain why females of wildebeest, but not zebra, avoided open riverine and closed woodland habitats, where grass quality is poor. Our results with zebra and wildebeest in KGR directly support this pattern in a predominantly woodland landscape. In cercopithecoid primates, group composition is skewed towards adult males under conditions of high predation risk [15], while studies of free ranging fish show that individuals actively alter shoal composition [16] to reduce predation risk as well as food competition [17]. Both live in great numbers on East Africa's vast plains, where dramatic wet and dry seasons cause a bounty of grass at sometimes, and a dearth of good grazing at others. Individuals in larger groups benefit from collective vigilance, cooperative defense, and dilution and confusion effects which can reduce predation risk [1]. Great herds of wildebeest, zebra, and other antelope gather in hundreds of thousands, to travel together across Tanzania and Kenya in search of good grazing, safe places to breed, and give birth. Be inspired & stay informed about Africa. In open scrub habitats, group size of wildebeest increased by 1.3 times (β = 0.259±0.100 SE, R2 = 0.338, Figure 3a) and those of zebra increased by 1.1 times (β = 0.101±0.084 SE, R2 = 0.544, Figure 3b) for every unit increase in lion UD. For more information about PLOS Subject Areas, click here. Change ), You are commenting using your Facebook account. All other predictor variables were included (tolerance levels >0.764 for all variables). Click through the PLOS taxonomy to find articles in your field. For this study, we used a vegetation map of KGR that was categorized into five habitat types that differ in vegetation density: Closed riverine (1.6% of area), Open riverine (15.8%), Closed woodland (54.4%), Open woodland (24.1%), and Open scrub habitat (4.1%), in order of decreasing structural density [19]. A herd of approximately 40 wildebeest approached the waterhole and one of the calves got confused and tried … On this particular day in Mkuze Game Reserve, at the Khumasinga Hide, a herd of zebra attacked a lost wildebeest calf. Zebra groups had proportionally fewer females in areas with high lion UDs (β = −0.040±0.032 SE) and in open scrub habitats (β = −0.043±0.048 SE). We also thank Konrad Hentze, University of KwaZulu-Natal (UKZN) for preparing the vegetation map and C. Tambling for helpful comments on an earlier version of this manuscript. On the other hand, wildebeest are natural water diviners. For both species, composition of groups was, however, dominated by males in open scrub habitats, irrespective of the probability of encountering lion. By contrast, zebra groups in KGR comprised of more females during the rainy season, which corresponded to the calving period, a time when vulnerability to predation risk is highest. There is no competition regarding food and everyone is happy. We used an information-theoretic approach to test a priori models that best explain group size and the proportion of females in groups for each species on the landscape. Yes Research for the use of unpublished data, and all K.e.r.i. https://doi.org/10.1371/journal.pone.0012758, Editor: Wayne M. Getz, University of California, United States of America, Received: June 30, 2010; Accepted: August 24, 2010; Published: September 20, 2010. In East Africa, an estimated 300,000 - 500,000 wildebeest calves are born every year between January - February. It’s like herding cats, with young animals running in all directions, getting separated from their mothers. When you spot a group of Zebras on your safari in Madikwe Game Reserve keep an eye out for Wildebeests (Gnus) as well. These benefits of grouping are weighed against the costs of sharing food [5], [6], and of increased probability of being detected by predators [7]. [32] for these two species in the larger Hwange National Park, Zimbabwe. © 2020 Rhulani. Both wildebeest and zebra were found in larger groups in areas with high lion UDs (β = 0.018±0.005 SE for wildebeest; β = 0.109±0.079 SE for zebra), but were in smaller groups in open scrub habitat (β = −0.321±0.343 SE for wildebeest; β = −0.437±0.348 SE for zebra). Collected the primary data: CRO MBO. Competing interests: The authors have declared that no competing interests exist. The last well known relationship with ostriches is the wildebeest. 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We examined the landscape-level distribution of groups of blue wildebeest, Connochaetes taurinus, and Burchell's zebra, Equus burchelli, in a predominantly woodland area (Karongwe Game Reserve, South Africa; KGR) to test the hypothesis that group dynamics are a function of minimizing predation risk from their primary predator, lion, Panthera leo. PLOS ONE promises fair, rigorous peer review, When families of zebra merge, thereby increasing group size, the resulting proportion of females to males continues to remain stable (Figure 2b). On this particular day in Mkuze Game Reserve, at the Khumasinga Hide, a herd of zebra attacked a lost wildebeest calf. Photo: Derek Keats CC BY 2.0. There are two theories about the origin of this alternative name (pronounced as either “new” or “g-new”) for wildebeests: one is that the name “gnu” originates from the Khoikhoi peoples name for wildebeests, which is t'gnu, while the other theory is that the name originates from the San peoples name for black wildebeest, !nu. Despite the low availability of open scrub in this landscape, both species selected this habitat type. For example, adult males of African ungulates are most at risk during the mating season [13], while adult females suffer highest predation risk during late gestation and immediately following parturition [14]. As the wildebeest have swarm intelligence, they can avoid the dangers on their way like when crossing the river or in open land. Tailored safari specialists. When and where to go in Africa, and with whom. For analyses, group size and lion UD values were square-root transformed and habitat type was included as dummy variables.