Geographic Range The gray or common duiker is found in the Sub-Saharan region of Africa from Senegal to Ethiopia. It also ranges from Eastern Africa to the southernmost tip of Africa (Nowak 1991). Biogeographic Regions

ethiopian native



Habitat This speices of duiker is found in areas of central, eastern, and southern Africa which provide sufficient amounts of cover. They inhabit savannas, grasslands, and woodlands. They also live in mountainous regions and are found at higher altitudes than any other African ungulates. They are not found in deserts or densely wooded areas such as the rainforests. (Kingdon, 1982; Nowak, 1991) Habitat Regions

tropical

terrestrial Terrestrial Biomes

savanna or grassland

forest

scrub forest

mountains

Physical Description The average weights, coloration, and ear size of the gray or common duiker vary with geographic location. Females generally weigh 2-4 kg more than males in a given region. On average, they are 60 cm in height at the shoulder and are 100 cm in length. Males have horns, which are spikes 7-18 cm and are heavily grooved at the base. Females usually do not have horns, but occasionally they may have stunted horns. Ears are 9.5-14.5 cm in length. Longer ears are found on duikers in open, arid habitats. Coloration varies from pale, light colored animals in dry regions, to dark gray colored in moist habitats. Mountain dwelling duikers have longer, thicker coats than duikers living in savannas, forests, and grasslands. (Kingdon, 1982) Other Physical Features

endothermic

homoiothermic

bilateral symmetry Sexual Dimorphism

female larger

ornamentation Range mass 12 to 25 kg 26.43 to 55.07 lb

Average length 100 cm 39.37 in

Reproduction The male and female form a monogamous breeding pair. There is no evidence of a peak breeding period (Estes 1991). Female duikers are known to give birth during all months of the year, and gestation is estimated to last 4-7 months (Kingdon 1982). Females find very secluded, thick cover to give birth. Normally only one young is born, but sometimes there are two. They are defended by both the male and female. The young reach adult size in 6 months and attain sexual maturity in 8-9 months (Nowak 1991). Key Reproductive Features

gonochoric/gonochoristic/dioecious (sexes separate)

sexual Range number of offspring 1 to 2

Average number of offspring 1 AnAge

Range gestation period 4.1 to 5.67 months

Average age at sexual or reproductive maturity (female)

Sex: female 255 days AnAge

Average age at sexual or reproductive maturity (male)

Sex: male 255 days AnAge Parental Investment

altricial

Behavior Duikers are active during the early morning, evening, and night. During the warm periods of the day, they remain bedded down in resting locations. Females rest near tree trunks or logs in places that are well hidden. Males rest in more elevated spots that allow greater visibility of the surrounding area. Both male and female duikers are territorial (Kingdon 1982). Territories of animals of the same sex have a small amount of overlap. A larger amount of overlap occurs between opposite sex animals, and a loose bond exists between the male and female in the same territory (Nowak 1991, Kingdon 1982). Territories are marked with scents from the preorbital gland and by vegetation that is horned by males. Females chase and butt intruding females. Males display threatening postures to intruding males, which include stalking and low-horn presentation. If these displays do not drive intruding males away, fights may occur. During fights, males chase and stab each other with their horns. The loser runs off or lies down in submission (Estes 1991). Key Behaviors

motile

solitary

social

Communication and Perception Perception Channels

tactile

chemical

Food Habits Duikers have been known to eat a wide variety of foods. They generally eat leaves and shoots from bushes, as well as fruits and flowers that drop to the ground due to the feeding of birds, monkeys, and fruit bats in trees. Duikers dig up roots, tubers, and bulbs with their hooves. The resin and bark of trees are occasionally a part of the duiker's diet. They have been known to eat insects, such as caterpillars, cockroaches, and ants. In uncommon instances, duikers have been seen stalking and eating lizards, frogs, rodents, and birds. Water requirements are met from moisture in the vegetation they consume. (Estes 1991, Kingdon 1982)

Economic Importance for Humans: Positive In certain African cultures, the horn is used to make pendants that are thought to ward off evil spirits (Kingdon 1982). Positive Impacts

food

Economic Importance for Humans: Negative Duikers dig up and eat potatoes, peanuts, and other crops in agricultural fields (Estes 1991).

The duiker has lived up to 14 years in captivity (Nowak 1991). Pythons have been found dead after being punctured by the duiker's horns during digestion (Kingdon 1982).

Contributors Arthur Cooper (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.

Glossary Ethiopian living in sub-Saharan Africa (south of 30 degrees north) and Madagascar. altricial 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. bilateral symmetry 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. chemical uses smells or other chemicals to communicate endothermic 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. food A substance that provides both nutrients and energy to a living thing. forest forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality. motile having the capacity to move from one place to another. mountains This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation. native range the area in which the animal is naturally found, the region in which it is endemic. scrub forest scrub forests develop in areas that experience dry seasons. sexual reproduction that includes combining the genetic contribution of two individuals, a male and a female sexual ornamentation 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. social associates with others of its species; forms social groups. solitary lives alone tactile uses touch to communicate terrestrial Living on the ground. tropical the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south. tropical savanna and grassland 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. savanna 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. temperate grassland 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.