Guenther's dik-dik is an endemic species of the Somali Arid Zone of East Africa. They are found in Somalia (excluding the extreme northeast and northwest, as well as the central coastal strip), the eastern and southern lowlands of Ethiopia, northern and eastern Kenya, northeastern Uganda and extreme southeastern Sudan. They are currently absent from northwestern Somalia, with their populations reduced in the Haud and lower Juba River drainage. (Kingswood et al., 1996; MSW Scientific Names)
Habitats ofare characterized by low thicket vegetation because they do not like to be away from cover. However, they do not thrive in dense growth because vision and movement are hindered. Preferred habitats include arid and semiarid thornbush, savanna grassland-woodland, and riverine grassland-woodland. Their numbers are greatest in areas that are over-grazed or disturbed because these areas have food at a level they can obtain it at. Roadsides and regenerating bush on old fields are preferred. Habitats range from areas with sandy soils to lava flats and low, rocky hills. (Kingdon, 1982; Kingswood et al., 1996)
Guenther's dik-diks are small, slender animals with long necks and small heads. Their hindquarters are usually located at the same level or higher than the shoulder. Their pelage is soft, with coloration ranging from yellowish gray to reddish brown on the dorsal side and white to grayish on the ventral. They have a short tail (3 to 5 cm long) which is hairy on the dorsal side and naked on the ventral side. Males have black horns that are short (up to 9.8 cm long) and are either straight or curved backward from the profile. These horns become more circular towards the tips and are ringed. Sometimes they are hidden by a tuft of hair on the forehead. Their eyes are large and black. Eyelids and preorbital glands are also black. The ears of dik-diks are large and white on the inside. Their legs are slender and long, with black hooves pointed anteriorly. Accessory hooves are diminutive. Since the females are larger and do not possess horns,are sexually dimorphic. Both sexes have a crest of hair, but the crest of males is typically more brightly colored and longer.
Another distinguishing feature of Guenther's dik-diks are their elongated snout that can be turned in all directions.can be distinguished from a similar species, Madoqua kirkii, by their longer nose. This snout results in reduced nasal and premaxillary bones. It is thought that their nose is a thermoregulatory device. Arterial blood is diverted to membranes in the snout and, through an evaporative process, is cooled.
Skulls of Guenther's dik-diks also have several distinctive characteristics. The cores of the horns are located behind the orbit in males. Premaxillae are thin anteriorly and then expand slightly. The nasals are undersized and wide. (Grzimek's Encyclopedia of Mammals, 1990; Kingdon, 1982; Kingswood et al., 1996; Nowak, 1999)
Guenther's dik-diks arrive at sexual maturity prior to their first year of age. They remain reproductively mature past their tenth year of age. The range of days of estrus in females is between one and seven, with the mean being 1.48. It is not influenced by seasonality and occurs year-round. Females standing with a decurved spinal position, called lordosis, are in estrus. Estrus is also signified by low levels of a urinary progesterone metabolite prior, during, or following estrus. The gestation period usually lasts from 170 to 180 days and litter size consists of one calf. They generally give birth twice a year. During parturition, the head appears first and the forelegs are laid back alongside the body. This differs from births among other ruminants, except the mouse deer. Post-partum estrus lasts about ten days after birth; consequently mating and parturition occur at the same time of year. This results in female dik-diks being pregnant for most of the year, including the time in which they have dependent young. Male fawns typically weigh between 725 and 792 grams at birth, while females weigh between 560 and 680 grams. Young are nursed for three to four months. Fawns, however, can start to eat solid food after about a week. The fawns are hidden for the first two to three weeks after birth. This concealing period is assisted by the mothers' ingestion of the afterbirth. The female stays with her young for the first few days after birth. She leaves frequently for short periods of time in order to feed, but soon these short periods become longer. Eventually females visit young four times a day- at sunrise, midday, dusk and sunset. For a few months after the concealing period, young fawns accompany both parents. The father takes no part in providing food for the young but has a parental relationship nonetheless. An example of this is that the male will groom the juvenile. As a result of this relationship, the father is more tolerant of his own young. Fawns are endured even in situations that would elicit aggression under normal circumstances. Fawns are contacted using calls made by the mother. When called to, the young comes out of the refuge. The young are silent during the day but may whistle at night.
The coloration of young dik-diks is identical to adults at birth. The ears, nose and legs are also well developed. Between seven and nine weeks, horns appear, although at first the crest hides them. The horns reach their full size at two years of age. At 34 weeks, horn annulations appear. Adult height is achieved at one year and adult weight at eight months. (Eltringham, 1979; Grzimek's Encyclopedia of Mammals, 1990; Kingdon, 1982; Kingswood et al., 1996; Robeck et al., 1997)
Guenther's dik-diks live in a territory of about three animals, an adult pair and one immature fawn. The juvenile is typically ejected after the female's first estrus after the birth of a new fawn. This estrus lasts around two days and brings out aggressive behavior in the male. Sometimes pairs occur within sight of each other. They are occasionally seen singly because pairs do not always stay together. If a member of a pair departs or dies, a replacement may join the group soon after or the surviving animal may remain alone. Territories are determined by heaps of dung about 12 inches in diameter deposited by dik-diks relative to the boundaries of the territory. This behavior may be one of the first acts in declaring a territory. Both sexes show this behavior, but males tend to do it more than females. Males paw the ground, urinate, and defecate. Males follow the females while they defecate, then urinate and defecate on the same spot. Postorbital gland secretions are also used to mark territories. Another method to define the territory is by sound. The males typically make a whistling noise when disturbed. An intrusion in their territory causes the dik-diks to bounce and then whistle upon landing. This whistling sounds like "zik-zik" or "dik-dik," hence their name. This encourages the grouping together of the family. The male also grates tree trunks with the corrugations on his horns to mark a territory. Only the male will defend the territory and territorial behavior peaks when the female is in estrus. Fights between males for territory are usually symbolic and infrequent. The result is either fleeing by one male or poking at vegetation followed by a dung ceremony.
Dik-diks are shy animals that will look for cover at the least bit of an alarm. They will seek out vegetation and then crouch flat on the ground. Their predators include hyenas, leopards, cheetahs, caracals, several other cats, jackals, baboons, eagles and pythons. They discriminate among these predators by their behavior. For example, if a leopard is nearby they will whistle. If a hyena approaches, they typically will just watch. Their defenses include their exceptional eyesight, alertness and speed, as well as knowledge of their home territory.
The courtship routine of dik-diks is unique. At first the female slows down her movements and appears to be dazed. She keeps her nose up when she walks by the male. At times she will show the male a patch of white hair near her haunch and flick her tail slowly. The male will focus on her facial region, especially the preorbital gland.
Guenther's dik-diks are chiefly diurnal, and are mostly active at night and in the evening. They stay active until approximately 3 a.m., and then rest shortly until daybreak. (Grzimek's Encyclopedia of Mammals, 1990; Kingdon, 1982; Kingswood et al., 1996; Nowak, 1999)
Guenther's dik-diks are highly selective browsers. They feed on particular parts of the plant, including the leaves and flowers of forbs, leaves, stems, flowers, fruits, seeds and pods of shrubs and trees. Grasses make up only a small portion of their diet (except for flowers and seeds), although they do chew at the tips of new grass on occasion. Guenther's dik-diks do not concentrate their feeding on one plant. They are adapted to dry conditions and feed on shrubs and trees that are rich in protein, as well as several xerophytic succulents. As an alternative to being concentrators, they wander and choose from an assortment of vegetation. Food items are very diverse and are usually of high nutritional value. The composition of their diet varies seasonally. Diet consists of the following plant species during the dry season: Acacia pennata, Combretum spp., Fagara merkeri, Grewia spp., Harrisonia abyssinica and Tamarindus indica. In the wet season, their diet includes Acacia senegal, Commiphora schimperi, Ipomoea and Leonotis nepetifola. They have also been known to browse on crops and orchards. They favor growing sesame buds of cultivated crops. Water is obtained from plant juices and dew. They can survive without drinking surface water.
generally feeds near to the ground and plucks food with its tongue and upper lip. They also have several special adaptations that allow them to acquire small leaves surrounded by thorns and to obtain nutrition in areas that fail to support larger browsers adequately. These adaptations include an elongated proboscis, narrow muzzle and tongue, and a slender body. They use their forelegs to pull the browse down from higher levels or stand in a bipedal position using twigs for forelimb support to obtain this food. On occasion, hooves or horns are used to dig for roots. The feeding habits of other browsers, primates, rodents and birds help to bring food within the reach of . These animals tend to scatter the ground with pods, buds, leaves and flowers, leaving them available for dik-diks to consume.
Dik-diks typically feed from dawn until mid-morning and then again from mid-afternoon until after dark. (Eltringham, 1979; Kingdon, 1982; Kingswood et al., 1996; Weyrauch et al., 1985)
Guenther's dik-diks are important game animals. In the early 1900's skins sold for export numbered in the hundreds of thousands. Currently they are hunted both legally and illegally. Their skins are used for karosses and are sold as "gazelle leather" for the making of gloves. At least two hides are needed to make a single pair of gloves. (Grzimek's Encyclopedia of Mammals, 1990; Kingdon, 1990; Kingswood et al., 1996)
Some hunters dislike Guenther's dik-diks because they warn and flush out larger game animals. (Nowak, 1999)
Guenther's dik-dik appears to be favored in the short term by ecological changes in the vegetation caused by human development. Consequently, they have survived despite severe habitat degradation in regions of Somalia. However, overhunting can be a problem. They have been hunted unremittingly by humans because they are easy to kill by such means as a thrown club and their numbers have decreased due to hunting in closely settled areas. At present population size is over 100,000. There is a possibility of risk in future years because there are fewer than three populations of at least 5,000 animals in managed areas. (Grzimek's Encyclopedia of Mammals, 1990; Kingdon, 1982; Kingswood et al., 1996)
Due to their elongated proboscis,and Madoqua kirkii are distinguished as a separate genus or subgenus, Rhynchotragus. Kingdon believes that this splitting is unnecessary and obscures the homogeneity of dik-diks. (Kingdon, 1982)
Kristi Jacques (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
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
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.
A substance that provides both nutrients and energy to a living thing.
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.
scrub forests develop in areas that experience dry seasons.
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
uses touch to communicate
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.
1999. "Convention of International Trade in Endangered Species of Wild Flora and Fauna" (On-line). Accessed November 21, 1999 at http://www.wcms.org.uk.
1990. Dik-diks. Pp. 331-340 in Grzimek's Encyclopedia of Mammals. New York: McGraw Hill Publishing Co..
1993. "MSW Scientific Names" (On-line). Accessed November 21, 1999 at http://www.nmnh.si.edu/cgi-bin/wdb/msw/names/query.
Eltringham, S. 1979. The Ecology and Conservation of Large African Mammals. Great Britain: Macmillan Press Ltd..
Kingdon, J. 1982. East African Mammals: An Atlas of Evolution in Africa. Chicago: University of Chicago Press.
Kingswood, S., A. Kumamoto.. 27 December 1996. Madoqua guentheri. Pp. 1-10 in Mammalian Species. American Society of Mammalogists.
Nowak, R. 1999. Walker's Mammals of the World. Baltimore and London: Johns Hopkins University Press.
Robeck, T., L. Fitzgerald, J. Hnida, C. Turczynski, D. Smith. December 1997. Analysis of urinary progesterone metabolites with behavioral correlation in Guenther's dik-dik (Madoqua guentheri). Journal of Zoo and Wildlife Medicine, 28(4): 434-442.
Weyrauch, K., A. Saber.. 1985. Fine structure of the fundic stomach epithelium of some East African game ruminants. Anatomischer Anzeiger, 158(5): 437-451.