Ogilby Ducker

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Ogilby Ducker
Ogilby duiker (Cephalophus ogilbyi)

Ogilby duiker ( Cephalophus ogilbyi )

Systematics
without rank: Forehead weapon bearer (Pecora)
Family : Horned Bearers (Bovidae)
Subfamily : Antilopinae
Tribe : Duiker (cephalophini)
Genre : Cephalophus
Type : Ogilby Ducker
Scientific name
Cephalophus ogilbyi
( Waterhouse , 1838)

The Ogilby-Ducker ( Cephalophus ogilbyi ) or Fernando-Po-Ducker is a type of duiker from central Africa . It occurs on the island of Bioko and on the continental mainland in southeastern Nigeria and southwestern Cameroon . The animals inhabit tropical rainforests of the lowlands and highlands. They are characterized by a golden brown color and a black stripe on the back, the front head is characteristic arched. Little is known about the Ogilby ducker's way of life. It was first described in 1838, in the course of the 20th century the white-legged duiker and the Brooke duiker were partially assigned to it as subspecies, but according to today's view, these are separate species. The Ogilby duiker is therefore considered in an expanded version as a species complex . The stock is considered to be endangered.

features

Habitus

The Ogilby duiker has a head-torso length of about 90 cm, plus a tail about 15 cm long. The shoulder height is about 56 cm, the weight is 18 to 20 kg. Outwardly, it is very similar to the closely related white-legged duiker ( Cephalophus crusalbum ) or the Brooke duiker ( Cephalophus brookei ). The back is typically arched, the legs are long and especially the rear limbs are extraordinarily strong. The fur is characterized by a deep golden brown to mahogany-like color, the back is more heavily colored than the sides. In general, the Ogilby duiker appears darker than the Brooke duiker. The throat and nape of the neck are hairy and have a brown tint, and there is also a zone with hair directed against the dashed line. An area of ​​darker hair also begins at the nape of the neck, which becomes thicker at the shoulders and develops into a narrow dark strip along the center line of the back. This runs to the root of the tail, but is only noticeable in some individuals from the middle of the back and is up to 3 cm wide. The belly side stands out from the darker back in a light golden brown. The legs are of a similar color to the body, but become darker towards the hooves, which is a clear difference to the white leg thickener. In addition, dark horizontal stripes can appear on the front legs. A tuft of gray hair is formed at the tail end. The cheeks are tinted similarly to the body, but the muzzle is blackish and the forehead is light reddish brown. A sparse tuft of hair on the parting varies in color from light orange to dark brown. The ears are large, around 8.8 cm long, and are marked with a white border. Both sexes have horns that are pointed backwards, as is typical for ducks, and are slightly curved inwards. Especially in males, they stand out due to characteristic transverse rings in the lower half. The horns of the males are on average 8.9 cm long, those of the females are usually slightly shorter at around 6 cm.

Skull features

Ogilby Ducker's skull

The skull becomes about 19.8 cm long, of which the anterior eye area takes up more than 10 cm. In the area of ​​the zygomatic arches , which are more curved than for example in the black duiker ( Cephalophus niger ), the width is 8.6 cm. Characteristic is the clear bulge of the forehead region behind the nasal bone - frontal bone contact. On the side, however, it does not stand out so clearly. The dentition is typical of Hornträger composed of 32 teeth dental formula is: . The length of the upper row of teeth averages 5.7 cm.

distribution

The Ogilby duiker is widespread in Central Africa and is mainly found on the island of Bioko in the Gulf of Guinea . On the mainland, its distribution area extends from eastern Nigeria east of the Cross River to southwestern Cameroon . The animals inhabit moist, evergreen rainforests of the lowlands, and on Bioko they are also found in mountain forests up to 2260 m in the Schefflera vegetation zone. A population density of around 10 to 13 individuals per square kilometer is assumed for the island . For the mainland, the figures vary; for the Korup National Park in the southwest of Cameroon they are around 4.5 to 6.3 individuals per square kilometer, for the Cross River National Park in southeast Nigeria they are 1.6 to 2 animals per square kilometer comparably large area. Other surveys, on the other hand, assume about 2 animals per square kilometer with a higher occurrence and 0.2 with a low distribution density. Possibly the total population amounts to a total of 12,000 animals, of which about 1,600 animals are in Cross River National Park.

Way of life

The Ogilby ducker's way of life has been little studied. It lives solitary, in pairs there are usually only mothers with young animals. Most activities during the day take place shortly after sunrise (6:30 a.m. to 11:00 a.m.) and just before sunset (4:00 p.m. to 7:00 p.m.). Lunchtime and the night are spent sleeping, with the animals looking for special resting places for the night. They each maintain their own territories which, according to observations by a male in the Korup National Park, are about 10.6 hectares in size and overlap with those of other individuals at the edge. However, it is unclear whether the animals are territorial. The central area of ​​the district serves exclusively as a rest area, there are also certain defecation points . The animals roam their territory in search of food. Nothing is known about food intake and reproduction. A seasonal restriction of reproduction is not assumed. On the island of Bioko, where the density of individuals is higher than on the mainland, there may be a more complex social structure. The animals communicate there with one another by making a loud “wheet” call.

Systematics

Internal classification of the genus Cephalophus according to Johnston et al. 2012
 Cephalophus  

  "Giant duiker"  


 Sylvicapra


   


 Cephalophus silvicultor


   

 Cephalophus spadix



   

 Cephalophus jentinki


   

 Cephalophus dorsalis





   

 Cephalophus zebra



   
  "East African red duiker"  



 Cephalophus rufilatus


   

 Cephalophus nigrifrons



   

 Cephalophus harveyi


   

 Cephalophus natalensis




   

 Cephalophus leucogaster



  "West African red duiker"  

 Cephalophus niger


   

 Cephalophus rubidus


   

 Cephalophus weynsi


   

 Cephalophus callipygus


   

 Cephalophus ogilbyi








   

 Cephalophus adersi



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The Ogilby duiker is a species from the genus Cephalophus and the horned bearer family (Bovidae). The genus forms part of the tribe of duikers (Cephalophini) within the horn-bearers , to which two other genera are included with Sylvicapra and Philantomba . The duikers mostly include smaller to medium-sized, compactly built representatives of the horn-bearers. These are endemic to Africa and, with the exception of the representatives of Sylvicapra , who inhabit savannah landscapes , are predominantly adapted to wooded habitats .

The genus Cephalophus forms the most species-rich group within the duiker. Molecular genetic studies from 2001 showed that there are three lines of development within the genus. These include the giant Ducker with the Jentink-Ducker ( Cephalophus jentinki ) and the bay duiker ( Cephalophus dorsalis ), next to the West African red duiker, such as the Peter Drucker ( Cephalophus callipygus ) and the black Ducker ( Cephalophus niger ) as well as the East African red duiker, so the Natal- Red duiker ( Cephalophus natalensis ) and the Harvey red duiker ( Cephalophus harveyi ). This classification of the genus Cephalophus was confirmed in principle by later studies published in 2012. Accordingly, the Ogilby duiker belongs to the West African red duiker and is closely related to the St. Peter's duiker. The splitting of the West African red duiker began in the Middle Pliocene around 3.7 million years ago, the separation of the Peters from the Ogilby duiker then took place in the Middle Pleistocene around 300,000 years ago. As a further result of the genetic investigations it turned out that Sylvicapra is the sister group of the giant duiker, which makes the genus Cephalophus appear paraphyletic . Therefore possibly the red duiker in need Cephalophus are released, it was suggested Cephalophorus as a generic name for this.

The first scientific description of the Ogilby Ducker was made by George Robert Waterhouse in 1838. He named his new species of antelope ogilbyi , for the description he had an individual from the island of Bioko (original name Fernando Póo) available, which Waterhouse also gave as a type area . He saw a closer relationship to the genus Tragelaphus (especially to the bushbuck , which, according to today's view, represents a species complex), which at that time was clearly defined and also included the large ( Strepsiceros ) and small kudus ( Ammelaphus ) as well as the eland ( Taurotragus ). With the species name ogilbyi , Waterhouse honored the Irish naturalist William Ogilby , who had made a great contribution to research into ruminants and horned animals . The inclusion in the genus Cephalophus is based on John Edward Gray from 1846 (whereby Gray had already used the name combination in the misspelling Cephalophorus ogilbyii in 1842 ).

Mainly in the course of the 20th century, the Ogilby duiker was assigned two other subspecies in addition to the nominate form , the Brooke duiker ( Cephalophus brookei ) and the white-legged duiker ( Cephalophus crusalbum ). The Brooke-Ducker was first described by Oldfield Thomas in 1903 on the basis of an individual from the vicinity of Cape Coast in Ghana . Thomas saw the Brooke duiker as a mainland form of the Ogilby duiker, but led it as a separate species. Only a short time later, in 1914, Ernst Schwarz combined the Brooke duiker with the Ogilby duiker, which was later confirmed by Jane St. Leger . In the period that followed, the status quo largely remained , so that in 1978 Peter Grubb introduced the white-legged ducker, citing around a dozen individuals from Gabon, as the third subspecies of the Ogilby ducker. It was not until the transition from the 20th to the 21st century that the Brooke duiker was first removed from the Ogilby duiker, and in a revision of the horn bearers by Colin Peter Groves and Peter Grubb in 2011, the white-legged duiker was also managed as an independent one. Other classifications see the Ogilby duiker in the broader sense as a single species, but indicate that it is a species complex consisting of three allopatric species.

Threat and protection

The IUCN lists the Ogilby-Ducker in the category "endangered" ( vulnerable ). The species is heavily hunted, especially on the island of Bioko, and the meat of the animals is then sold to local markets as bushmeat . Studies in the 1990s showed that around 3200 animals were sold in the markets each year, which at that time corresponded to around 1.6 individuals killed per square kilometer. Given an assumed population growth rate of 2 births per square kilometer, this amount was considered unsustainable. In some regions of the island, the Ogilby duiker was the fourth most hunted species. At the beginning of the 21st century, around 209 animals were killed for the bushmeat market in a 33-month study in the north of the island. On the mainland, too, the Ogilby duck population has been severely decimated by hunting. The species occurs in several nature reserves, such as the Cross River National Park in Nigeria and the Korup National Park in Cameroon. On Bioko, the animals are found in the Gran Caldera de Luba reserve in the south and in the Pico Basile reserve in the center of the island. The first reserve in particular is important for the survival of the Ogilby duckers on the island.

literature

  • Colin P. 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 , p. 765
  • Jonathan Kingdon: Cephalophus ogilbyi Ogilby's Duiker. In: Jonathan Kingdon, David Happold, Michael Hoffmann, Thomas Butynski, Meredith Happold and Jan Kalina (eds.): Mammals of Africa Volume VI. Pigs, Hippopotamuses, Chevrotain, Giraffes, Deer and Bovids. Bloomsbury, London, 2013, pp. 272-275

Individual evidence

  1. ^ A b c Peter Grubb: A new antelope from Gabon. Zoological Journal of the Linnean Society 62 (4), 1978, pp. 373-380
  2. ↑ a b c d e Colin P. 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 , p. 765
  3. ↑ a b c d e Jonathan Kingdon: Cephalophus ogilbyi Ogilby's Duiker. In: Jonathan Kingdon, David Happold, Michael Hoffmann, Thomas Butynski, Meredith Happold and Jan Kalina (eds.): Mammals of Africa Volume VI. Pigs, Hippopotamuses, Chevrotain, Giraffes, Deer and Bovids. Bloomsbury, London, 2013, pp. 272-275
  4. ^ A b John E. Fa, Javier Juste, Jaime Perez del Val and Javier Castroviejo: Impact of Market Hunting on Mammal Species in Equatorial Guinea. Conservation Biology 9 (5), 1995, pp. 1107-1115
  5. ↑ Sacha Marc Anton Viquerat, Kadiri Serge Bobo, Mareike Müller, Christian Kiffner and Matthias Waltert: Estimating Forest Duiker (Cephalophinae) Density in Korup National Park: A Case Study on the Performance of Three Line Transect Methods. South African Journal of Wildlife Research 42 (1), 2012, pp. 1-10
  6. ↑ a b Saka O. Jimoh, Emmanuel T. Ikyaagba, Abideen A. Alarape, Adesoji A. Adeyemi and Matthias Waltert: Local depletion of two larger Duikers in the Oban Hills Region, Nigeria. African Journal of Ecology 51, 2012, pp. 228-234
  7. ↑ a b c IUCN SSC Antelope Specialist Group: Cephalophus ogilbyi. The IUCN Red List of Threatened Species 2016: e.T4148A50183770 ( [1] ); last accessed on September 14, 2016
  8. ↑ a b c d Anne R Johnston and Nicola M Anthony: A multi-locus species phylogeny of African forest duikers in the subfamily Cephalophinae: evidence for a recent radiation in the Pleistocene. BMC Evolutionary Biology 12, 2012, p. 120 ( [2] )
  9. ↑ Bettine Jansen van Vuuren and Terence J. Robinson: Retrieval of Four Adaptive Lineages in Duiker Antelope: Evidence from Mitochondrial DNA Sequences and Fluorescence in Situ Hybridization. Molecular Phylogenetics and Evolution 20 (3), 2001, pp. 409-425
  10. ↑ Alexandre Hassanin, Frédéric Delsuc, Anne Ropiquet, Catrin Hammer, Bettine Jansen van Vuuren, Conrad Matthee, Manuel Ruiz-Garcia, François Catzeflis, Veronika Areskoug, Trung Thanh Nguyen and Arnaud Couloux: Pattern and timing of diversification of Cetartiodactalia, Lauriala (Mammia ), as revealed by a comprehensive analysis of mitochondrial genomes. Comptes Rendus Palevol 335, 2012, pp. 32-50
  11. ^ Colin Groves: Current taxonomy and diversity of crown ruminants above the species level. Zitteliana B 32, 2014, pp. 5-14
  12. ^ George Robert Waterhouse: On some new species of Mammalia from Fernando Po. Proceedings of the Zoological Society 1838, pp. 57-61 ( [3] )
  13. ^ John Edward Gray: Descriptions of some new genera and fifty unrecorded species of Mammalia. Annals and Magazine of Natural History 10, 1842, pp. 255–267 ( [4] )
  14. ^ John Edward Gray: Description of the species of Cephalophus (H. Smith) in the collection of the British Museum. Annals and Magazine of Natural History 18, 1846, pp. 162–168 ( [5] )
  15. ↑ Oldfield Thomas: A new duiker from West Africa. Annals and Magazine of Natural History 7 (11), 1903, pp. 289–291 ( [6] )
  16. ^ Ernst Schwarz: Notes on African ungulates. Annals and Magazine of Natural History 8 (13), 1914, pp. 491–495 ( [7] )
  17. ^ J. St. Leger: A key to the species and subspecies of the subgenus Cephalophus. Proceedings of the Zoological Society of London 1936, pp. 209-228
  18. ^ Fenton PD Cotterill: Species concepts and the real diversity of antelopes. In: A. Plowman (Ed.): Ecology and Conservation of Mini-antelope: Proceedings of an International Symposium on Duiker and Dwarf Antelope in Africa. Fuerth. 2003, pp. 59-118
  19. ↑ Peter Grubb: Genus Cephalophus. In: Don E. Wilson and DeeAnn M. Reeder (Eds.): Mammal Species of the World. A taxonomic and geographic Reference. Johns Hopkins University Press, Baltimore MD 2005, ISBN 0-8018-8221-4 ( [8] )
  20. ↑ Colin Groves and Peter Grubb: Ungulate Taxonomy. Johns Hopkins University Press, 2011, pp. 1–317 (SS 272–273)
  21. ↑ Montserrat Colell, Carmen Mate and John E. Fa: Hunting among Moka Bubis in Bioko: dynamics of faunal exploitation at the village level. Biodiversity and Conservation 3, 1994, pp. 939-950
  22. ↑ María Grande-Vega, Miguel Ángel Farfán, Ambrosio Ondo and John E. Fa: Decline in hunter offtake of blue duikers in Bioko Island, Equatorial Guinea. African Journal of Ecology 54 (1), 2016, pp. 49-58

Web links

Commons : Ogilby-Ducker  - collection of images, videos and audio files