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Blue (Common) Wildebeest - Connochaetes taurinus
Topic Started: Jul 14 2012, 07:15 AM (2,630 Views)
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Blue (Common) Wildebeest - Connochaetes taurinus

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Scientific classification
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Mammalia
Order: Artiodactyla
Family: Bovidae
Subfamily: Alcelaphinae
Genus: Connochaetes
Species: Connochaetes taurinus


The blue wildebeest, also called the common wildebeest or the white-bearded wildebeest, is a large antelope and one of two species of wildebeest. The name “blue wildebeest” derives from a conspicuous silvery blue sheen to its short haired hide, differentiating this species from the plainer black wildebeest. The largest population is in the Serengeti, numbering over one million animals.

Subspecies
C. taurinus consists of five subspecies: C. t. taurinus (blue wildebeest or brindled gnu; southern Africa) individuals are silvery slate gray in colour, the origin of the common name "blue" wildebeest. C. t. johnstoni (Nyassaland wildebeest), occurring in southeastern Tanzania and northern Mozambique), is the largest subspecies. The western white-bearded wildebeest (C. t. mearnsi) is the smallest and is found only in southwestern Kenya and northwestern Tanzania. C. t. mearnsi is the darkest hued wildebeest while C. t. albojubatus (eastern white-bearded wildebeest) is the palest in colouration and found in southeastern Kenya and northeastern Tanzania. The last subspecies, Cookson's wildebeest (C. t. cooksoni), is restricted to the Luangwa Valley. While most subspecies have an at least partially black beard, C. t. mearnsi and C. t. albojubatus both have pale beards, as also suggested by their common names, western and eastern white-bearded wildebeest.

Habitat

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Blue wildebeest are found in open and bush-covered savanna in south and east Africa, thriving in areas that are neither too wet nor too arid.

They can be found in places that vary from overgrazed areas with dense bush to open woodland floodplains. Wildebeests prefer the bushveld and grasslands of the southern savanna. The terrestrial biome designations for these preferred habitats are savanna, grassland, open forest and scrub forest. Blue wildebeests can tolerate arid regions, as long as a potable water supply is available. Since all wildebeests require a long drink every day or two, they must have water within about 15 to 25 km distance.

Description
The blue wildebeest is one of the largest species of antelope. It can stand 118 to 145 cm (46 to 57 in) high at the shoulder. The head-and-body length can range from 150 to 250 cm (59 to 98 in) and the tail length ranges from 56 to 100 cm (22 to 39 in). Body mass is typically from 120 to 275 kg (260 to 610 lb). The record sized female and male weighed 260 kg (570 lb) and 290 kg (640 lb) respectively.

Young blue wildebeest are born tawny brown, and begin to take on their adult coloration at age nine weeks. The adult's hue actually varies from a deep slate or bluish gray all the way to light gray or even grayish-brown. The dorsal coat and flanks are slightly lighter in hue than the ventral hide and underparts. Dark brown vertical bands of slightly longer hair mark the neck and forequarters, and from a distance lend a perception of skin wrinkling. The manes of both sexes appear long, stiff, thick and jet black, a color assumed by the tail and face as well.

Blue wildebeest have a beefy, muscular, front-heavy appearance with a distinctive robust muzzle. It strides with relatively slender legs and moves gracefully and quietly most of the time, belying the reputation for stampeding in herds; however the stampeding characteristic may sometimes be observed.

Probably the most conspicuous feature of the blue wildebeest are the large horns shaped like parentheses, extending outward to the side and then curving up and inward. In the male the horns can attain a total span of almost 90 cm, while the female's horn width is about half the size of the male's. These cow-like horns of both sexes are somewhat broad at the base and are without ridges.

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Ecology
The Serengeti herds are purely migratory and abandon the usual plains after the rainy season has ended to seek higher grasses in wetter areas. Herds may be mixed gender with a dominant male, female only, or bachelor only. Blue wildebeest often graze together with other species such as plains zebras for purposes of mutual protection. Zebras in particular are beneficial to co-exist with since they mow down highly vegetated areas leaving the wildebeests to eat the newly exposed and more nutritional short grasses, which is what they prefer.

Blue wildebeest are unusually territorial, adult males occupying their territories for a month or for the entire year. The physical size of territories ranges from one to two hectares. The bulls mark territory boundaries with dung heaps, preorbital gland secretions, hoof scent glands and pawing of the earth. When competing over territory, males grunt quite loudly, make a thrusting motion with their horns and perform other displays of aggression.

They are a major prey item for lions, hyenas, and crocodiles.

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Reproduction
The mating process is thought to begin at the first full moon at the end of the rainy season. Once territory is established, the male attempts to lure or corral the female into his domain.

Female wildebeest give birth in the middle of a herd rather than go out alone. The gestation period is approximately 8.5 months, with calves able to stand within seven minutes and run with the herd in less than two hours from birth. These precocial features are warranted since the calves are vulnerable to predators. To escape predation calves remain close to the mother for a significant time, and in fact may suckle for up to one year. In large herds 80 percent of wildebeest offspring survive the first month, compared to a 50 percent survival rate within small herds.

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Edited by Taipan, Jul 28 2012, 10:17 PM.
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10,000 Wildebeest Drown in Migration "Pileup"

Blake de Pastino
National Geographic News
October 1, 2007



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In a bizarre mishap that conservationists describe as "heartbreaking," an estimated 10,000 wildebeest have drowned while attempting to cross Kenya's Mara River during an annual migration.

The deaths, which occurred over the course of several days last week, are said to account for about one percent of the total species population.

The drownings created a grotesque wildlife pileup, after part of the migrating herd tried to ford the Mara at "a particularly treacherous crossing point," according to Terilyn Lemaire, a conservation worker with the Mara Conservancy who witnessed the incident.

The first animals into the river failed to cross and drowned, while others continued to stampede into the water behind them, Lemaire told National Geographic News by email.

"Once they jumped into the water, they were unable to climb up either embankment onto land and, as a result, got swept up by the current and drowned," she said.

Some 2,000 wildebeest drowned at the crossing in a single afternoon, Lemaire estimated.

"There was no unusual flooding at the time, and there seems to be no extraneous circumstances to these deaths," she said.

"The wildebeest merely chose a crossing point that was too steep."

Drowning deaths are not uncommon during the migration, Lemaire added, but her organization has never witnessed fatalities on this scale.

"It is customary every year for the wildebeest to pick a particularly treacherous crossing point and for there to be a significant die-off," she said, "but the number of deaths during these crossings almost never exceeds one thousand."

More than a million wildebeest undertake an epic migration every year in late summer, leaving their calving grounds in the Serengeti Plain of Tanzania to seek greener pastures in Kenya to the north.

The animals, also known as gnu, journey some 2,000 total miles (3,200 kilometers) each year, often joined by thousands of zebras and Thomson's gazelles.

The deaths occurred at Kenya's Maasai Mara National Reserve, as the herd was beginning its swing to the east on its way back to the Serengeti.

Since the drownings, the animals' bodies have washed downriver, beaching on the Mara's muddy banks and getting caught under a nearby bridge, Lemaire wrote on her blog for the nonprofit WildlifeDirect.

The remains formed what she described as "pungent islands of bloated carcasses."

"The crocodiles, storks, and vultures have not had to worry about where to find their next meal," she wrote.

"Those that aren't consumed will be left and will eventually decompose in the water. These thousands of carcasses will undoubtedly affect the health of the water, but to what extent, only time will tell."

Lemaire also declined to speculate, in her email to National Geographic News, on the impact the mass deaths might have on the wildebeests' overall population health.

"I would imagine that such a significant decrease in population would have an effect," she said, "but what that effect would be and to what extent, I cannot say."



Link: http://news.nationalgeographic.com/news/2007/10/071001-wildebeest_2.html
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