Wildebeest

This article is about the animal. For other uses, see Wildebeest (disambiguation).

"Gnu" redirects here. For other uses, see Gnu (disambiguation).

Wildebeest
Blue Wildebeest, Ngorongoro Crater, Tanzania
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Subphylum:	Vertebrata
Class:	Mammalia
Order:	Artiodactyla
Family:	Bovidae
Subfamily:	Alcelaphinae
Genus:	Connochaetes Lichtenstein, 1812
Species
Connochaetes gnou – black wildebeest Connochaetes taurinus – blue wildebeest

The wildebeest (plural wildebeest, wildebeests or wildebai), also called the gnu ( /ˈnuː/ noo or /ˈnjuː/ new)^[1] is an antelope of the genus Connochaetes. It is a hooved (ungulate) mammal. Wildebeest is Dutch for "wild beast" or "wild cattle" in Afrikaans (beest = cattle), while Connochaetes derives from the Greek words konnos ("beard") and khaite ("flowing hair").^[2] The name "gnu" originates from the Khoikhoi name for these animals, "gnou".

Gnus belong to the family Bovidae, which includes antelopes, cattle, goats, and other even-toed horned ungulates. Connochaetes includes two species, both native to Africa: the black wildebeest, or white-tailed gnu (C. gnou), and the blue wildebeest, or brindled gnu (C. taurinus). Fossil records suggest that these two species diverged about one million years ago resulting in a northern and a southern species. The blue wildebeest changed very little from the ancestor species, while the black wildebeest took on more morphological changes to adapt to a habitat of open grassland in the south. Today there are five subspecies of the blue wildebeest while the black wildebeest has no living subspecies.^[3] In East Africa, the wildebeest is the most abundant big game species, both in population and biomass.^[4]

Physiology

Video of wildebeest feeding its foal, South Africa

A full grown wildebeest can be 4 ft 2 in (1.27 m) to 4 ft 10 in (1.47 m) at the shoulder and weigh 265–600 lb (120–270 kg). They inhabit the plains and open woodlands of Africa, especially the Serengeti National Park, a UNESCO World Heritage Site in Tanzania, Masai Mara Game Reserve in Kenya and Liuwa Plain National Park in Zambia. Wildebeest can live more than 30 years, though their average lifespan is around 20 years.^[5] The wildebeest have a broad muzzle shaped like a lawnmower which helps it with eating short grass.^[4]

Differences between blue and black wildebeest

The main differences between the black and blue wildebeest are the amount of horn curvature and the color of fur. The blue wildebeest is the bigger of the two species, standing taller and weighing more than the black wildebeest.^[3] In males, the blue wildebeest stand 150 cm tall at the shoulder and weigh around 250 kg^[6] while the black wildebeest stands 111 to 120 cm tall^[7] and weighs about 180 kg.^[8] In females, the blue wildebeest have a shoulder height of 135 cm and weigh 180 kg^[6] while the black wildebeest females stand 108 cm at the shoulder and weigh 155 kg.^[8] The horns of blue wildebeest protrude to the side then curve downwards before curving up back towards the skull while the horns of the black wildebeest curve forward than downward before curving at the upwards at the tips. Blue wildebeest tend to be a dark grey color with stripes, but may have a shiny blue color. The black wildebeest has brown colored fur with a mane that ranges in color from cream to black, and a tail that is cream colored at the end. The blue wildebeest lives in a wide variety of habitats that includes woodland and grassland while the black wildebeest tends to reside exclusively in open grassland areas.^[3] The blue wildebeest migrates over long distances in the winter, whereas the black wildebeest does not.^[9] The milk of the female black wildebeest contains higher protein, lower fat, and lower lactose content than the milk of female blue wildebeests ^[10]

Early life

Wildebeest calves are mostly born at the same time (90% are born in a three week timeframe) and this also provides the young with protection. The numbers of wildebeest calves are so vast that each individual’s survival chances are much greater than if a calf was born outside the three week birthing period. Immediately after they are born, wildebeest calves start following their mothers. However, these young calves suffer from high mortality and only those with the best genetic endowments and who have experienced mothers survive through the first few years of life.^[4]

Behavior

Migration

Wildebeest herding and following a few leading zebra in the Masai Mara, Kenya

Wildebeest are known for their annual migration to new pastures. Wildebeest usually begin their migration in the months of May or June when drought forces them to go on the move. However, if it is a particularly dry year, they may begin their migration earlier than usual because of the decrease in vegetation. The reason that the wildebeest is a migratory animal is because the grass that it feeds on is not a very good provider of energy and minerals, so it has to move around in order to get adequate nutrition. Factors that affect migration include food, water, predators, and also phosphorus level. Phosphorus is a crucial element that is necessary for all life forms, and it has been found that grass during the dry season has a very low phosphorus content, and at an insufficient level for the wildebeest’s survival if it remained stationary. As a result, the wildebeest migrates to other grazing areas to feed on grass that has higher phosphorus.^[4] A 1992 study by Ben-Shahar and Coe found that besides phosphorus, wildebeest also migrated to areas where the grass had higher nitrogen levels ^[11] Ecologists have found that the main reason that wildebeest migrate is to find high quality food during the whole year, although the reduction of predation is another positive benefit.^[4]

In 1974, high concentrations of wildebeest decreased green biomass on the Serengeti Plains by close to 400 grams per square meter. However, this grazing was good for the grassland because it kept the net productivity up. There was a significant association of Thomson's Gazelle grazing in areas that had been already frequented by wildebeest^[12] Numerous documentaries feature wildebeest crossing rivers, many being eaten by crocodiles or drowning in the attempt. While having the appearance of a frenzy, recent research has shown that a herd of wildebeest possesses what is known as a "swarm intelligence", whereby the animals systematically explore and overcome the obstacle as one.^[13] Major predators that feed on wildebeest include the lion, hyena, cheetah, leopard, and crocodile, which seem to favor the wildebeest.^[5] Wildebeest, however are very strong and can inflict considerable injury to even a lion. Wildebeest have an apparent maximum running speed of around 64 km/h (40 mph).^[14] The primary defensive tactic is herding, where the young animals are protected by the older larger ones while the herd runs as a group. Typically the predators attempt to cut out a young or ill animal and attack without having to worry about the herd. Wildebeest have developed additional sophisticated cooperative behaviors, such as animals taking turns sleeping while others stand guard against a night attack by invading predators. Scientists are unsure how much is learned behaviorally and how much is hard wired into the DNA of the animal.^{[citation needed]} Wildebeest migrations are closely followed by vultures, as wildebeest carcasses are an important source of food for these scavengers. The vultures consume about 70% of the wildebeest carcasses available. Decreases in the number of migrating wildebeest have also had a negative effect on the vultures.^[15] In recent years, Botswanan authorities placed thousands of kilometers of fences across the Kalahari. These fences prevented wildebeests from reaching watering holes and grazing grounds, resulting in the deaths of tens of thousands of individuals, and dropping the wildebeest population to less than ten percent of its previous size. For the blue wildebeests, although the majority of the population migrates, there are some populations that do not migrate and live a sedentary lifestyle. These groups can be found in the Ngorongoro Crater, Selous, Hwange, and Esotha.^[4]

Interactions with Non-predators

Zebras and wildebeest group together in open savannah environments when there is a high chance of predation. This grouping strategy reduces predation risk because larger groups decrease each individual’s chance of being hunted, and also because predators are more easily seen in open areas.^[16]

Wildebeest can also listen in on the alarm calls of other species, and by doing so can reduce their risk of predation. One study showed that along with other ungulates, wildebeests responded more strongly to the baboon alarm calls compared to the baboon contest calls even though both types of calls had similar patterns, amplitudes, and durations. The alarm calls were a response of the baboons to lions, and the contest calls were recorded when there was a dispute between two males.^[17]

Breeding and Reproduction

Due to their migratory ways, the wildebeest do not form permanent pair bonds or defend a set territory. The wildebeest mating season is called rut, and during this time the males establish temporary territories and try to attract females. These small territories are about 3000 square meters, with up to 300 territories in a square kilometer. The males defend these small territories from other males while trying to lure in females that are ready to mate. The males entice females into their territories with grunts and distinctive antics. Wildebeest usually breed at the end of the rainy season when the animals are most fit.^[4] The mating season usually occurs between May to July and the birthing period usually takes place between January to March, at the start of the wet season. The gestation period is about 8 to 9 months, and the average estrous cycle is about 23 days. Wildebeest females breed seasonally and ovulate spontaneously.^[18] Groups of wildebeest females and young live in the small areas established by the male. When groups of wildebeest join together, there is a larger female to male ratio as the females flock to the areas held by fewer males.^[16] It has also been suggested that this female dominated sex ratio may be due to illegal hunting and human disturbance. Higher male mortality has been attributed to illegal hunting.^[19]

Hybrids

Due to their confinement in small areas in South Africa, the two species of wildebeest, the black wildebeest and the blue wildebeest have interbred, resulting in fertile hybrid young. These two species are brought into close contact with each other on game farms and reserves in South Africa. The resulting hybrid young may include characteristics of both species and even some intermediate traits. The hybrids also tended to have strange dental, horn, and skull shapes.^[3]

Human Uses

Wildebeest are killed for food, especially for biltong, which is dried game meat. Biltong is a delicacy and an important food item in Africa.^[4] It has been found that the meat of females is more tender than that of males, and that meat was the most tender during the autumn season.^[9] Wildebeest are a regular target for illegal meat hunters because they are relatively easy for hunters to kill. When preparing the wildebeest, the carcass is usually cut into 11 pieces. The estimated price for wildebeest meat is about US$ 0.47 per kilogram.^[20]

References

1. ^ Gnu Answers.com
2. ^ Comparative Placentation: Wildebeest, Gnu
3. ^ ^{a b c d} Ackermann, Rebecca; James S. Brink, Savvas Vrahimis, Bonita de Klerk (2010). "Hybrid Wildebeest (Artiodactyla: Bovidae) Provide Further Evidence For Shared Signatures of Admixture in Mammalian Crania". South African Journal of Science 106 (11/12): 90–94. doi:10.4102/sajs.v106i11/12.423. 
4. ^ ^{a b c d e f g h} Ulfstrand, Staffan (2002). Savannah Lives: Animal Life and Human Evolution in Africa. OXford: Oxford University Press. 
5. ^ ^{a b} "Wildebeest". National Geographic. http://animals.nationalgeographic.com/animals/mammals/wildebeest/. Retrieved December 16, 2010. 
6. ^ ^{a b} "Trophy Hunting Blue Wildebeest in South Africa". http://www.africanskyhunting.co.za/trophies/bluewildebeest-hunting.html. 
7. ^ Lundrigan, Barbara. "Connochaetes gnou". http://animaldiversity.ummz.umich.edu/site/accounts/information/Connochaetes_gnou.html.. Retrieved 29 April 2011. 
8. ^ ^{a b} "Trophy Hunting Black Wildebeest in South Africa". http://www.africanskyhunting.co.za/trophies/blackwildebeest-hunting.html. 
9. ^ ^{a b} Hoffman, Louw; Schalkwyk, Sunet van; Muller, Nina (2009). "Effect of Season and Gender on the Physical and Chemical Composition of Black Wildebeest (Connochaetus Gnou) Meat". South African Journal of Wildlife Research 39 (2): 170–174. doi:10.3957/056.039.0208. 
10. ^ Osthoff, G.; A. Hugo, M. de Wit (2009). "Comparison of the Milk Composition of Free-ranging Blesbok, Black Wildebeest and Blue Wildebeest of the Subfamily Alcelaphinae (family: Bovidae)". Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology 154 (1): 48–54. doi:10.1016/j.cbpb.2009.04.015. 
11. ^ Ben-Shahar, Raphael; Malcolm J. Coe (1992). "The Relationships between Soil Factors, Grass Nutrients, and the Foraging Behaviour of Wildebeest and Zebra". Oecologia 90 (3): 422–428. doi:10.1007/BF00317701. 
12. ^ McNaughton, S.J. (1975). "Serengeti Migratory Wildebeest: Facilitation of Energy Flow by Grazing". Science 191 (4222): 92–94. doi:10.1126/science.191.4222.92. PMID 17834943. 
13. ^ "Wildebeest Migration – Must See on African Safari Vacation". Tanzenar. June 4, 2009. http://tanzanear.com/blog/wildebeest-migration-must-see-on-african-safari-vacation/. Retrieved December 16, 2010. 
14. ^ "Wildebeest - Speed of Animals". Speed of Animals. http://www.speedofanimals.com/animals/wildebeest. Retrieved December 16, 2010. 
15. ^ Virani, Munir Z.; Corinne Kendall, Peter Njoroge, Simon Thomsett (2011). "Major Declines in the Abundance of Vultures and Other Scavenging Raptors in and around the Masai Mara Ecosystem, Kenya". Biological Conservation 144 (2): 746–752. doi:10.1016/j.biocon.2010.10.024. 
16. ^ ^{a b} Thaker, Maria; Abi T. Vanak, Cailey R. Owen, Monika B. Ogden, Rob Slotow (2010). Getz, Wayne M.. ed. "Group Dynamics of Zebra and Wildebeest in a Woodland Savanna: Effects of Predation Risk and Habitat Density". PLoS ONE 5 (9): e12758. doi:10.1371/journal.pone.0012758. PMC 2942830. PMID 20862216. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2942830. 
17. ^ Kitchen, Dawn M.; Thore J. Berman, Dorothy L. Cheney, James R. Nicholson, Robert M. Seyfarth (2010). "Comparing Responses of Four Ungulate Species to Playbacks of Baboon Alarm Calls". Animal Cognition 13 (6): 861–870. doi:10.1007/s10071-010-0334-9. PMID 20607576. 
18. ^ Clay, A. Moss; R.D. Estes, K.V. Thompson, D.E. Wildt, S.L. Monfort (2010). "Endocrine Patterns of the Estrous Cycle and Pregnancy of Wildebeest in the Serengeti Ecosystem". General and Comparative Endocrinology 166 (2): 365–371. doi:10.1016/j.ygcen.2009.12.005. PMID 20036667. 
19. ^ Ndibalema, Vedasto G. (2009). "A Comparison of Sex Ratio, Birth Periods and Calf Survival among Serengeti Wildebeest Sub-populations, Tanzania". African Journal of Ecology 47 (4): 574–582. doi:10.1111/j.1365-2028.2008.00994.x. 
20. ^ Ndibalema, Vedasto G.; Alexander N. Songorwa (2008). "Illegal Meat Hunting in Serengeti: Dynamics in Consumption and Preferences". African Journal of Ecology 46 (3): 311–319. doi:10.1111/j.1365-2028.2007.00836.x. 

External links

• Information and Research on wildebeest movements in Masai Mara