Litocranius walleri inhabits the dry brushy region of east Africa from the Serengeti plain of Tanzania north along the coast through Kenya, Ethiopia, Eritrea, and into southern Somalia. The species was once found in eastern Egypt and northeastern Sudan as well. (Parker, 1990)
The habitat that Litocranius walleri occupies varies from the treeless plains of Tanzania in the southern reaches of its range to the dry high deserts of Kenya. They are adaptable and do well in a variety of habitats, provided there is a good supply of succulent plants. (Macdonald, 1984)
The long neck and long, thin legs of gerenuks are their defining features; these make them one of the world's most easily recognized antelopes. The coat is of a short, fine, glossy hair that is evenly distributed over the whole body. The pelage is a pale tawny brown with white along the breast, underbelly, and inner legs. There are small, dark patches of fur on the knees of the forelegs and at the end of the tail. The head is long and narrow with medium-sized ears, and the cheek teeth and masseter muscle are reduced. On the head there is a dark patch around the eyes that pales as it goes outward until it forms a white rim. Only males of this species have head ornamentation in the form of scimitar shaped horns ranging from 25 to 44 centimeters in length. Both sexes of L. walleri are of similar size but the males are more muscular than females causing them to outweigh them. Mass ranges from 29 to 58 kg, total body length from 140 to 160 cm, and tail length from 220 to 350 mm. (Fiorenza, 1983)
The mating ritual of Litocranius walleri is complex. When a male encounters a potential mate the female will raise her nose into the air and pull her ears close to the head as a sign of defensiveness, meanwhile the male displays his horns and neck in a sideways pose. If the female is receptive then the male will mark the female on the thigh with the contents of his preorbital gland and contiue to follow her around, a form of mate guarding. As the male follows the female he continually uses his forelegs to kick the female in her thigh region. When the female atempts to urinate the male performs the flehmen test or lip curl test in which he samples her urine. Once the female comes into estrous the male will notice the difference in the females urine and mating will begin. Males will attempt to mate with as many females as they can. (Macdonald, 1984)
Gerenuk females breed every one to two years, depending on the sex of their previous year's offspring. Males are dependent on their mothers for longer than are females. Reproduction and births occur throughout the year and may depend on the quality of available nutrition. Females give birth to usually one young after a gestation period of about 165 days.
Female Litocranius walleri usually give birth to one young, rarely two. The young are precocial and begin to walk within minutes of birth. The female continues to look after her young until she weans them. Young females get weaned when they reach one year of age but male offspring are not weaned until they reach at least one and a half years old and stay with their mothers until after they are two. (Parker, 1990)
Litocranius walleri have never been an abundant species. At Tsavo National Park in Kenya, where L. walleri is protected and enjoys good habitat, researchers have concluded that L. walleri makes up less then .5% of the total biomass of hoofed mammals in the park. Because they do not form large populations and their food is of limited supply they exhibit strange social interactions. Males are solitary and very territorial, they only associate with females during the mating season or when they are young. Dominant males establish territories by marking trees and shrubs with their preorbital gland. Other dominant males will enter another's territory without any aggression or defensiveness being displayed but a young male without its own territory will be run off if it enters a dominant male's territory. The size of a males territory can range from 300 to 850 acres and can support several indivduals. Females form small bands of up to about 10 individuals, usualy related adults with young. These groups of females and young roam freely throughout male territories. Young males that have just been weaned often form bachelor herds that roam nomadically until they become mature enough to establish their own territories and breed.
Litocranius walleri is well adapted for obtaining forage from their arid habitats. Their long necks, long legs, and the ability to stand on their hind legs allows L. walleri to obtain tree leaves that are out of reach for most other antelope species. This permits gerenuks to be selective in the foods they eat and to be efficient browsers of herbaceous plants. Over 80 different species of plants have been found in a single individuals stomach. L. walleri does not drink free standing water, they instead rely on water taken in when they eat succulent plants. (Parker, 1990)
Several anti-predator adaptations have evolved in Litocranius walleri for their survival both while they are juveniles and as adults. Young L. walleri remain motionless while hiding in the bushes and tall grasses not far from their mothers during the day when the mother is feeding. As adults they show an adaptation that is more common to forest dwelling antelopes than to desert-adapted ones, they freeze at the aproach of danger. They are preyed on by a diverse set of large predators found throughout their range. (Macdonald, 1984)
Although rare, gerenuk contribute to nutrient cycling in the ecosystems in which they live through their foraging activity. They also act as prey species for large predators.
Litocranius walleri has been a game animal in Africa for over 200 years. Although they are limited in supply for hunters and have a limited range, they continue to be hunted for trophies and for bush meat. In the expanding world of photosafaries and parks in Africa L. walleri will become a regular subject for this endeavor. Unfortunately L. walleri doesn't do well in captivity and has rarely been bred in zoos. (Parker, 1990)
There are no adverse effects of L. walleri on humans.
Litocranius walleri is a game animal, even though its not very common, and as a game animal it is protected in most of its range in the form of tags or permits. There are many parks offering sanctuary for them within their range and many biologists and game managers studying them so they are not considered to be at significant risk currently. (Macdonald, 1984)
Jamie Payne (author), Humboldt State University, Brian Arbogast (editor), Humboldt State University.
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
uses sound to communicate
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
uses smells or other chemicals to communicate
in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.
humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
parental care is carried out by females
union of egg and spermatozoan
an animal that mainly eats leaves.
A substance that provides both nutrients and energy to a living thing.
An animal that eats mainly plants or parts of plants.
fertilization takes place within the female's body
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
generally wanders from place to place, usually within a well-defined range.
chemicals released into air or water that are detected by and responded to by other animals of the same species
having more than one female as a mate at one time
communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
one of the sexes (usually males) has special physical structures used in courting the other sex or fighting the same sex. For example: antlers, elongated tails, special spurs.
associates with others of its species; forms social groups.
uses touch to communicate
Living on the ground.
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
Fiorenza, P. 1983. Encyclopedia of Big Game Animals of Africa. New York City, New York, USA: Larousse and Co. Inc..
Macdonald, D. 1984. The Encyclopedia of Mammals. New York NY: Facts on File Publications.
Parker, S. 1990. Grizimek's Encyclopidia of Mammals vol 5. New York NY: McGraw-Hill Publishing Company.