its range and its access to water resources. So as I study 

 the animal's long-standing natural adaptations, I also 

 am on the lookout for changes that may threaten the 

 survival of the Serengeti herds. 



Wildebeests are particularly well-suited to har- 

 vest the abundant short grasses that cover 

 certain semiarid plains during the rainy seasons. The 

 best-known such habitat is provided by the plains 

 of the eastern Serengeti, where an impermeable 

 hardpan underlies a fertile layer of volcanic soil. The 

 grasses there are highly nutritious because they take 

 up calcium and phosphorus trapped by the hardpan. 

 They produce abundant forage during the short 

 rainy season of November through December and, 

 more predictably, in the long rains of April and May. 

 Meanwhile, the nutrients in the manure wildebeests 

 spread across the grasslands are recycled by millions 

 of dung beetles. 



In good years the pastures remain green across the 

 seasonal gap between the rains, from January through 

 March. But from June through October there is lit- 

 tle or no rain, and the green of the short-grass plains 

 turns to tan. The animals then have little choice but 

 to leave their pastures in search of grazing and wa- 

 ter in adjoining regions — where there is more rain- 

 fall, and the grasses are taller (though less nutritious) 

 and stay greener longer. 



Newborn wildebeest gains its feet just a few minutes after birth. Even at the 

 height of the calving season, the large aggregation of animals must keep moving 

 from pasture to pasture. Hence, unlike the offspring of most antelopes, the young 

 cannot adopt the strategy of remaining concealed from predators. Instead, they 

 must be able to move almost immediately with the herd. 



The wildebeest's feeding apparatus — a wide muz- 

 zle, a broad row of incisors, and flexible lips — is well 

 adapted for taking big bites of short grass. And m 

 overall build the wildebeest has evolved to survive 

 the rigors of migration and evade predators. The 

 body mass is concentrated in the upper torso and 

 thick neck, and is supported by long, relatively 

 spindly legs, which enable the animal to run in bursts 

 as fast as forty miles an hour. In addition, the wilde- 

 beest has high shoulders and a back that slopes down 

 to lower hindquarters, a configuration that locomo- 

 tion specialists believe is energetically efficient for 

 traveling long distances at an easy canter. The spot- 

 ted hyena, the ranking predator of wildebeests, has 

 a similar conformation. 



The openings of the wildebeest's nostrils are 

 equipped with flaps that help filter the dust stirred 

 up by thousands of migrating animals. Pungent se- 

 cretions from glands in the front hooves help wilde- 

 beests follow each other by scent, even on the dark- 

 est nights. The wildebeest's dark color and reverse 

 countershading (darker below and lighter above — 

 the opposite of most antelopes) make it conspicu- 

 ous and unlikely to be confused with any other 

 herbivore. This uniform helps bind wildebeests to- 

 gether, but it also makes them conspicuous to preda- 

 tors. Their antipredator strategy must therefore 

 rely on vigilance and flight. 



^^^^ T he protagonist of the Serengeti, 

 ■ the western white-bearded wilde- 

 flj beest, C. taurinus mearnsi, has the 

 n| darkest coloration of the five rec- 

 ognized subspecies of C. taurinus. It 

 also features the shortest horns and 

 the most vociferous bulls. By 

 weight, wildebeests are the sixth 

 largest of Africa's seventy-one ante- 

 lope species, but C. t. mearnsi is the 

 smallest subspecies: females average 

 about 360 pounds, males about 

 460. Small size can be an advantage 

 in hard times; in any event, it en- 

 ables more individuals to concen- 

 trate on a pasture. Mitochondrial 

 DNA studies by geneticist Nicholas 

 J. Georgiadis, director of the Mpala 

 Research Centre in Kenya, indicate 

 that the subspecies has been sepa- 

 rated for millennia from its closest 

 relative, the eastern white-bearded 

 wildebeest, by the western wall of 

 the Gregory Rift Valley. 



The wildebeest and two other 

 major migratory species — the zebra 

 and Thomson's gazelle — return to 



30 



NATUKAI HISTORY September 2006 



