Defassa waterbuck

Defassa waterbuck
	Defassa waterbuck ( ♂ ) in Murchison Falls National Park in Uganda.
Systematics
without rank:	Forehead weapon bearer (Pecora)
Family :	Horned Bearers (Bovidae)
Subfamily :	Antilopinae
Tribe :	Reduncini
Genre :	Waterbuck ( Kobus )
Type :	Defassa waterbuck
Scientific name
	Kobus defassa
	( Rüppell , 1835)

The Defassa waterbuck ( Kobus defassa ) is an African antelope from the genus of waterbuck . The distribution area extends from Gambia and the southern Sengal in the west to western Ethiopia and south to the part of Zambia north of the Muchinga Mountains . In Kenya and Tanzania, the Defassa waterbuck occurs only to the west of the Great Rift Valley , east of which is the distribution area of the elliptical waterbuck ( Kobus ellipsiprymnus ). Isolated populations of the Defassa waterbuck can be found in Angola and in small savanna areas in southern Gabon and western Congo .

Olive green - the original range of the Defassa waterbuck, yellow-green that of the elliptical waterbuck

features

The Defassa waterbuck reaches a head body length of 175 to 235 cm and a shoulder height of 120 to 136 cm and is therefore, together with the very similar elliptical waterbuck, the largest antelope of the genus Kobus . The tail has a length of 33 to 40 cm. The clearly fluted horns of the males can be 75 to 84 cm long. They are bent back slightly and then turn upwards in a twist. Females are polled. The fur is coarse and shaggy and has a reddish-gray basic color, although it can be gray or more reddish depending on the individual. It has a sweet, musky odor due to secretions excreted from glands. The belly side and the inside of the legs vary in color from whitish to dark brown. In general, the fur of the Defassa waterbuck is more reddish than that of the elliptical waterbuck. Except for a narrow white ring directly above the hooves, the legs are dark. The top of the head is often reddish with a blackish stripe that extends from the nose to between the eyes. The lips, the eyebrows and a strip directly on the nose are white. A sickle-shaped, white band runs from the upper throat area to below the ears. The ears are relatively short and rounded, their insides are white. The most striking feature with which the Defassa waterbuck can be distinguished from the elliptical waterbuck is the mirror , which in the Defassa waterbuck is whitish throughout and does not reach above the tail, while the elliptical waterbuck shows a white ellipse on its rear that reaches over the tail. The dental formula is: . ${\ displaystyle {\ frac {0.0.3.3} {3.1.3.3}}}$

Habitat and way of life

The Defassa waterbuck is found in steppes, savannas, bushland and open forests, with the females preferring areas protected by vegetation, while the males can be seen more in open grassland. However, dense forests are avoided. The animals are only a few kilometers away from open water, but also go to arid regions when they are close to the water. In contrast to other Kobus species, the Defassa waterbuck does not flee into the water when threatened, but rather looks for dense bushes. The density of individuals varies depending on the region. At Lake Nakuru in Kenya, 10 to 100 animals were counted over an area of one square kilometer. In Uganda there were 2.1 to 17.7 individuals per square kilometer. In West Africa the populations are much lower with 0.4 specimens per km² in Senegal and 0.02 to 0.21 animals per square kilometer in the Comoé National Park in the northeast of the Ivory Coast.

Defassa waterbuck can be active both during the day and at night. The main activity time is in the morning and evening. When the sun is at its highest point between noon and 2 p.m., the animals usually rest. They each spend more than 35% of their time eating and resting. The periods of foraging for the females are longer, while the males rest longer (approx. 50%). The rest period is usually spent under sheltered vegetation, while the animals go to the open grassland to eat. Most of the night is spent ruminating and deep sleep only lasts 4 to 6 minutes.

The Defassa waterbuck feeds primarily on grass. However, the composition of the food changes depending on the season. In the rainy season, annual grasses are mainly eaten; in the dry periods, more than half of their diet consists of perennial grasses. Leaves are also eaten. In contrast to the elliptical waterbuck, the Defassa waterbuck does not graze on flood plains.

Social and territorial behavior

The social behavior of the Defassa waterbuck has been thoroughly researched, especially in Uganda. The females live in unstable groups whose composition and size keep changing. During the rainy season the groups with three to six individual animals are rather small, while in the dry season up to 25 animals can gather at the watering holes. The territory inhabited by a single female is approximately 6 km², while that of the more territorial males only has an average area of 1.5 km². The territory of one female therefore overlaps the territories of several males. Males defend their territory fiercely against other sexually mature males, bachelor groups are tolerated now and then, but not during the rutting season . The composition of the bachelor groups is relatively stable with a hierarchy that depends on age and size. The territories of adult males are often on the banks of rivers and lakes and are particularly attractive to females because of their constantly green vegetation. Males also try to prevent females from leaving their territory. The boundaries of the area are not marked, only visually checked. At Lake Nakuru it was observed that males who own territory tolerate one to three more sexually mature males in their territory, but males who are subservient to the landowner. These "satellite males" help to defend the territory, thereby have access to better food sources and have a better chance of taking over the territory when the male who owns the territory has become too old. The old males, displaced from a territory, live solitary for the rest of their lives.

Reproduction

Two females

Defassa waterbuck reproduce all year round. Most births, however, take place during the rainy season, in Kenya between July and January, in Uganda in March and April and in October and November, and in Zambia between November and April with a peak in January. Females ready for conception are pursued by the pleading male. If it stops to urinate, the male lets the urine run down his nostrils and mouth. The mating is preceded by a run stroke, i.e. H. the male kicks the hind legs or torso of the female with the front leg. The oestrus lasts about 18 hours and during this time the female mates up to nine times with one or more males. The gestation period is 272 to 287 days. Usually only a single cub is born, weighing around 14 kg at birth. But there are also reports of twin births. The young spend the first two to four weeks of their lives hidden in the bushes. The female is only a few hundred meters away and only visits her young animal during the day and at night to suckle it. The young are weaned at 6 to 8 months of age. Females become sexually mature between the ages of two and three years. Males typically leave their mother at eleven months of age and then join a bachelor party. With them, the ripening begins at the age of two years and is only completed at the age of 5 to 6 years. Then they have reached the size and horn length of the adult animals and they try to occupy their own territory. In the wild they reach an average age of eleven years, females live on average 13 years old. A human kept female lived to be 23 years old.

Systematics

Drawing from the first description from 1835

The Defassa waterbuck was first scientifically described in 1835 by the German scientist and Africa explorer Eduard Rüppell under the name Antilope defassa . Terra typica is the area around Lake Tana in the highlands of Ethiopia. Later it was assigned to the genus Kobus and the elliptical waterbuck ( Kobus ellipsiprymnus ) described by the Irish naturalist William Ogilby in 1833 as a subspecies. However, exact investigations of the microsatellites showed clear differences between the two waterbuck forms, so that the Defassa waterbuck was made an independent species in 2011 by the British-Australian mammalogen Colin Groves and his colleague Peter Grubb as part of a comprehensive revision of the ungulate systematics. In Nairobi National Park and Samburu National reserve in Kenya hybridize both. The introgression however, is limited, possibly due to differences in the genome of a larger gene flow prevented between the two species. Several subspecies have been described in the distribution area of the Defassa waterbuck. However, the species is currently considered to be monotypical , as the differences between these subspecies are no greater than those between individuals in a population.

Danger

The IUCN estimated the population at 60,000 to 80,000 fully-grown specimens in 2016 and lists the Defassa waterbuck as potentially endangered (Near Threatened). Compared to the elliptical waterbuck, the Defassa waterbuck has a larger distribution area, but it is rarer there and its habitat is more fragmented. In West Africa it has meanwhile disappeared from most of the former distribution area. The reason lies in the hunting and the conversion of savannahs, open forests and steppes into pastures and arable land.

Individual evidence

↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j Colin Peter Groves and David M. Leslie Jr .: Family Bovidae (Hollow-horned Ruminants). In: Don E. Wilson and Russell A. Mittermeier (eds.): Handbook of the Mammals of the World. Volume 2: Hooved Mammals. Lynx Edicions, Barcelona 2011, ISBN 978-84-96553-77-4 , pp. 444-779 (pp. 681-682)
↑ Eduard Rüppell: New vertebrates belonging to the fauna of Abyssinia. Schmerber, Frankfurt 1835-1840. doi: 10.5962 / bhl.title.53778
↑ Colin Groves and Peter Grubb: Ungulate Taxonomy. Johns Hopkins University Press, 2011, pp. 1–317 (SS 191–196)
↑ Lorenzen, ED, BT Simonsen, PW Kat, P. Arctander & HR Siegismund. 2006. Hybridization between subspecies of waterbuck ( Kobus ellipsiprymnus ) in zones of overlap with limited introgression. Molecular Ecology 15: 3787-3799. DOI: 10.1111 / j.1365-294X.2006.03059.x
↑ Kobus ellipsiprymnus ssp. defassa in the endangered Red List species the IUCN 2017. Posted by: IUCN SSC Antelope Specialist Group, 2016. Retrieved on January 30 of 2019.

[HMW-1] ↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j Colin Peter Groves and David M. Leslie Jr .: Family Bovidae (Hollow-horned Ruminants). In: Don E. Wilson and Russell A. Mittermeier (eds.): Handbook of the Mammals of the World. Volume 2: Hooved Mammals. Lynx Edicions, Barcelona 2011, ISBN 978-84-96553-77-4 , pp. 444-779 (pp. 681-682)

[Rüppell-2] Eduard Rüppell: New vertebrates belonging to the fauna of Abyssinia. Schmerber, Frankfurt 1835-1840. doi: 10.5962 / bhl.title.53778

[Groves&Grubb-3] Colin Groves and Peter Grubb: Ungulate Taxonomy. Johns Hopkins University Press, 2011, pp. 1–317 (SS 191–196)

[Lorenzen-4] Lorenzen, ED, BT Simonsen, PW Kat, P. Arctander & HR Siegismund. 2006. Hybridization between subspecies of waterbuck ( Kobus ellipsiprymnus ) in zones of overlap with limited introgression. Molecular Ecology 15: 3787-3799. DOI: 10.1111 / j.1365-294X.2006.03059.x

[IUCN-5] Kobus ellipsiprymnus ssp. defassa in the endangered Red List species the IUCN 2017. Posted by: IUCN SSC Antelope Specialist Group, 2016. Retrieved on January 30 of 2019.