Dik-dik

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For the pop group, see Dik Dik.
Dik-dik [1]
Madoqua kirkii - male (Namutoni).jpg
Male, Kirk's dik-dik from Etosha National Park, Namibia
Madoqua kirkii - female (Namutoni).jpg
Female partner of the male dik-dik in the above picture
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Family: Bovidae
Genus: Madoqua
(Ogilby, 1837)
Species

A dik-dik is a small antelope in the genus Madoqua that lives in the bushlands of eastern and southern Africa. Dik-diks stand about 30–40 cm (12–16 in) at the shoulder, are 50–70 cm (20–28 in) long, weigh 3–6 kg (7–16 lb) and can live for up to 10 years. Dik-diks are named for the alarm calls of the females. In addition to the females' alarm call, both the male and female make a shrill, whistling sound. These calls may alert other animals to predators.

Physical characteristics

Female dik-diks are somewhat larger than males. The males have horns, which are small (about 3 in or 7.5 cm), slanted backwards and longitudinally grooved. The hair on the crown forms an upright tuft that sometimes partially conceals the short, ribbed horns of the male. The upper body is gray-brown, while the lower parts of the body, including the legs, belly, crest, and flanks, are tan. A bare black spot below the inside corner of each eye contains a preorbital gland that produces a dark, sticky secretion. Dik-diks insert grass stems and twigs into the gland to scent-mark their territories.

To prevent overheating, dik-diks have elongated snouts with bellows-like muscles through which blood is pumped. Airflow and subsequent evaporation cools this blood before it is recirculated to the body. However, this panting is only implemented in extreme conditions—dik-diks can tolerate air temperatures of up to 40 °C (104 °F).[2]

Habitat

The dik-dik lives in shrublands and savannas of eastern Africa. Dik-diks seek habitats with plentiful supply of edible plants such as shrubs. Dik-diks may live in places as varied as dense forest or open plain, but they require good cover and not too much tall grass.[3] They usually live in pairs in territories of about 5 hectares (12 acres). The territories are often in low, shrubby bushes (sometimes along dry, rocky streambeds) with plenty of cover. Dik-diks can blend in with their surroundings, because of their dusty colored fur. Dik-diks have a series of runways through and around the borders of their territories.[4]

Diet

Dik-dik eating
Male, Tarangire National Park, Tanzania
Family of Kirk's dik-dik, Lake Manyara, Tanzania

Dik-diks are herbivores. Their diet mainly consists of foliage, shoots, fruit and berries, but little or no grass. They receive sufficient amounts of water from their food, making drinking unnecessary. Like all even-toed ungulates, they digest their food with the aid of micro-organisms in their four-chambered stomachs. After initial digestion, the food is repeatedly eructated and rechewed, a process known also as rumination, or 'chewing the cud'. Dik-diks' tapering heads may help them eat the leaves between the spines on the acacia trees, and feed while still keeping their head high to detect predators.[2]

Reproduction

Dik-diks are monogamous,[5] and conflicts between territorial neighbors are rare. When they occur, the males from each territory dash at each other, stop short, vigorously nod their heads and turn around. They will repeat this process, increasing the distance each time until one stops. Males mark their territories with dung piles, and cover the females' dung with their own.[6] Monogamy in dik-diks may be an evolutionary response to predation;[7] surrounded by predators, it is dangerous to explore, looking for new partners.[8] Pairs spend about 64% of their time together. Males, but not females, will attempt to obtain extra-pair mating when the opportunity arises.[5]

Females are sexually mature at 6 months and males at 12 months. The female gestates for 169 to 174 days and bears a single offspring. This happens up to twice a year (at the start and finish of the rainy season). Unlike other ruminants, the dik-dik is born with its forelegs laid back alongside its body, instead of them being stretched forward. Females weigh about 560 to 680 g (1.2–1.4 lb) at birth, while males weigh 725 to 795 g (1.5–1.7 lb). The mother lactates for six weeks, feeding her fawn for no longer than a few minutes at a time. The survival rate for young dik-diks is 50%. The young stay concealed for a time after birth, but grow quickly and reach full size by seven months. At that age, the young are forced to leave their parents' territory. The fathers run the sons off the territory and the mothers run off the daughters.[9]

Predators

Dik-diks are hunted primarily by monitor lizards, caracals, lions, hyenas, wild dogs and humans. Other predators include leopards, cheetahs, jackals, baboons, eagles, hawks and pythons. Dik-diks' adaptation to predation include excellent eyesight and the ability to reach speeds up to 42 km (26 mi) an hour.[4]

Classification

The four species of dik-dik are:[1]

References

  1. ^ a b Grubb, P. (2005). "GENUS Madoqua". In Wilson, D. E.; Reeder, D. M. Mammal Species of the World (3rd ed.). Johns Hopkins University Press. pp. 637–722. ISBN 978-0-8018-8221-0. OCLC 62265494. 
  2. ^ a b Dik dik. African Wildlife Foundation. Web. 4 February 2010.
  3. ^ Brynn Schaffner and Kenneth Robinson. Savanna. Blue Planet Biomes.
  4. ^ a b The Living Afridca: Wildlife Bovid Family. library.thinkquest.org
  5. ^ a b Brotherton, PNM; Pemberton, JM; Komers, PE; Malarky, G (1997). "Genetic and behavioural evidence of monogamy in a mammal, Kirk's dik-dik (Madoqua kirkii)". Proceedings. Biological sciences / the Royal Society 264 (1382): 675–681. doi:10.1098/rspb.1997.0096. PMC 1688408. PMID 9178540. 
  6. ^ Dik-Diks – Territorial Behavior – Male, Territory, Offspring, and Female. Science.jrank.org. Retrieved on 2012-05-26.
  7. ^ Brotherton, PNM; Manser, MB (1997). "Female dispersion and the evolution of monogamy in the dik-dik". Animal Behaviour 54 (6): 1413–1424. doi:10.1006/anbe.1997.0551. PMID 9794769. 
  8. ^ National Geographic "Earth Almanac", June 1996
  9. ^ Scheibe, E. (1999). Madoqua kirkii. Animal Diversity. University of Michigan Museum of Zoology. Web. 27 January 2010.