Southern / Common Reedbuck (Redunca arundinum)

Southern/Common Reedbuck

Redunca arundinum (Boddaert, 1785)

Common Reedbuck

Photo: Deon Furstenburg     

AfrikaansRietbok
GermanGrossriedbock
FrenchRedunca grande
isiZuluInhlangu
isiXhosaIntlangu
seSothoLekwena
seTswanaSebogata
ShonaBimha
TshivendaDavhu


These graceful antelope are so called because they hide in reeds and the tall grass of marshes during the day.  When alarmed they give a distinctive, shrill whistle produced by closing their mouths and blowing through their nostrils.  They display a characteristic bushy white tail when running and have an unusual white tube over the base of each horn.

There is some confusion over the naming of this species as it is sometimes referred to as the Common Reedbuck and sometimes the Southern Reedbuck.  This is further confused by an additional division of a subspecies also named southern.  For the purposes of this article the species nomenclature Common will be used and the subspecies, southern.

IUCN Conservation Status:

•    Southern / Common reedbuck = Lower Risk, least concern (LR/lc).
•    Bohor reedbuck = Least Concern (LC)

Taxonomy  

Classification     

KingdomANIMALIA
Phylum
CORDATA
Class:
MAMMALIA
Supercohort:LAURASIATHERIA
Cohort:FERUNGULATA
Superorder:CETARTIODACTYLA
Order:
RUMINANTIA
Suborder:PECORA
Superfamily:BOVOIDEA
Family:
BOVIDAE
Sub-family:
Antilopinae
Tribe:
Reduncini
Genus:
Redunca
Species:arundinum


The genus Redunca consists of three species namely
•    R. redunca the bohor reedbuck of eastern and northern sub-saharan Africa, with five sub-species
•    R. fulvorufula the mountain reedbuck with three sub-species
•    R. arundinum the common reedbuck of central and southern Africa, with two sub-species
•    R.a. arundinum  the southern common reedbuck (Boddaert, 1785) found to the south of the Zambezi River
•    R.a. occidentalis  the northern common reedbuck (Rothchild, 1907) found to the north of the Zambezi River and with a distribution slightly overlapping that of the bohor reedbuck

The tribe Reduncini also includes the genera Kobus which hosts the waterbucks and Pelea, the grey rhebuck Pelea capreolus.  Despite the similarity in their names, the grey rhebuck and the reedbucks are not closely related.

Historically, the common reedbuck was found down the east of southern Africa to the Swellendam regions in the Western Province of South Africa.  They were particularly plentiful in the foothills of the Drakensberg escarpment.  The distribution in the Cape began to shrink during the 1950’s until they were only found to the east of the Sundays River.  In the 1970’s it was declared a red data species and by 1984 it had vanished from both the Cape and Free State Provinces.  This rapid decline in their numbers together with a high level of fragmentation and localization of their distribution was due mostly to the destruction of their specialized habitat of marshes due to human development.  Since 1990, small breeding herds of common reedbuck from reserves in KwaZulu-Natal have been moved back into their former distribution range.

Description

The body colour of the common reedbuck varies from a buffy-grey to a light greyish-brown or buffy-yellow.  These colours act as an efficient camouflage as they blend in with the grass and reed environments of their habitat.  A dark brown tint on the front of the forelegs is distinctive.  The underside of the body is white and the flanks show a gradient of gentle colour transition.  A black spot can be seen below the base of each ear.  Common reedbuck have inguinal glands in the groin and lack pre-orbital glands.  The mouth and nostrils have a greyish-white outline and a whitish half-moon marking on the throat which is more noticeable in rams.  The tail is short and very bushy with a white tip and underside.  Rams are slightly larger than ewes having a mean body mass 68 kg and a mean shoulder height of 105 cm against the 51 kg and 95 cm of the ewes respectively.

Comparison to Man

Common Reedbuck comparison to man

Trophy

Only the males carry horns which appear as buds at six months and grow straight until an age of 14 months when the ends start to bend slightly forward and sideways.  They are heavily grooved from the base for 65% of their length.  From an age of 11 months, the outer keratin layer at the base of the horns dries out to form a thick layer of flakes giving the impression of a white tube surrounding the horn.  At two years the flake tubes extend upwards for 20% of the horns’ length.  Above the tubes, the first half of the horn is shiny black and the remainder a dull greyish-black.  The full half-circle of the adult horn is reached at 3.5-4 years and trophy status after 5.5 years.

Habitat requirement

Competition with other animals is minimal as the common reedbuck has evolved to survive in a very specialized habitat that is avoided by most other game species.  The most essential habitat parameters are tall grass veld, gently sloping foothills and a water-rich zone such as riverine habitats, seepage lines, swamps, marshlands, shores of dams and lakes, water-logged floodplains or small permanent pans.  Patches of tall grass or reeds 90-200 cm high serve as protection and refuge.  They never move further than 200 m from this refuge as it is more important than the nutritional value of the forage.  Common reedbuck habitat includes broken woodland, savannah and temperate and coastal grassland.  The foothills of granite or quartzite sandstone are preferred together with the adjacent ecotones bordering the plains.  Reedbuck cannot tolerate a major change of habitat such as that caused by fire, drought, overgrazing, animal competition or human destruction.  They are water dependent and need access to a daily supply.  Open plains without shelter, forests, woody thickets and steep mountain slopes are not suitable.

Distribution

Common Reedbuck past and present distribution

Behaviour

Common reedbuck are primarily nocturnal, and are active from late afternoon until dawn.  During dry winters their activity extends into daylight.  Although water dependent, common reedbuck do not readily enter deeper water but limit themselves to grazing on vegetation growing in shallow water about 20cm deep.  They use fixed pathways to move between grazing grounds and water on a daily basis, with a result that the same animals are frequently seen at the same sites.  During most of the daylight hours they lie in hollows between reeds or tall grass.

When danger approaches from a distance, common reedbuck frequently gives a sharp high-pitched whistle through their noses, similar to that of the mountain reedbuck and grey rhebuck.  This is a very distinctive sound often heard in the evening. If approach closer, it remains lying motionless until the very last moment and then rapidly gallops off.  The running speed is relatively slow in comparison to most other African antelope and they rely on their cryptic camouflage to remain unseen.  This behaviour is a major drawback when they are hunted by feral dog packs.  It is extremely difficult to approach common reedbuck without being seen as they feed mainly at head height giving them a constant view of their surroundings.

Feeding & Nutrition

Common reedbuck are ruminants that predominantly graze.  During moist summer months the diet consists mainly of grass.  In a dry winter, small amounts of browse and the young green shoots of herbaceous plants are utilized in order to supply further moisture and trace elements.  In winter, when the cover of the primary habitat of foothills is destroyed by fire or competitive grazing by other herbivores, they tend to move downhill to riverine areas.

Common reedbuck are highly selective of the more palatable new growth of most grass species at its preferred grazing height of 8-130 cm.  This buck is therefore classified as a selective, tall grass grazer.  It is not particularly selective of plant species and thrives in both sour-veld and mixed-veld with grasses of a marginal nutritional value.  Sweet-veld is less suitable due to its drier environment.  The burning of large portions of veld usually displaces common reedbuck from the area as the loss of refuge is a greater disadvantage than the benefit of gaining new fodder growth.  In addition, the influx of other animal species attracted by the new growth results in an increased competition.

Important dietary grasses include:  thatch-grass Hyparrhenia dissoluta, giant spear-grass Trachypogon spicatus, guinea buffalo-grass Pannicum maximum, spear-grass Heteropogon contortus, Andropogon amplectens, blue baffalo-grass Cenchrus cilliaris, Sporobulus spp, swamp-grass Leersia hexantha, Rhodes grass Chloris gayana, turf grass Ischaemum brachyatherum and reeds Phragmites communis.  When feeding in marshes reedbuck, wade into the water and mud to a depth of 20 cm.  The major grazer competitors are sable, zebra, waterbuck, eland, buffalo and recently introduced lechwe.

Social structure

Common reedbuck are semi gregarious and semi-social.  They are predominantly found alone, in pairs or in small breeding groups of 3-6 individuals.  During dry winter months, larger temporary groups of up to 15 are occasionally seen.  There is no strict family bonding among members and little physical social contact ever occurs.  Mating partners are seldom found in close proximity and, for the most part, remain 30-80 m apart.

Juveniles of 8-10 months are chased away from the breeding groups and either become solitary nomads or form small bachelor groups of 2-4 that roam the perimeters of the mating pairs’ territories.  Sexually mature, but still socially inferior sub-adults disperse to look for new habitats in order to establish home ranges.  Collared sub-adults of two years have been found in a new home range 40 km from their place of birth.  The rams become socially mature at 3.5-4 years at which stage they challenge larger territorial rams and try to displace them.  Shortly before birth, the ewe chases away the previous lamb which must then survive alone.

In habitats that provide a high quality fodder throughout the year, such as the St Lucia wetlands, territorial behaviour is not economic and is replaced with a hierarchical system that incorporates larger social groups.  In environments with a large seasonal variation in nutritional quality and fodder supply such as the highlands of KwaZulu-Natal, territorial behaviour is temporarily restricted to the rutting season.  In other habitats only mating pairs are territorial and each partner roams the same territory independently of the other.  An additional scenario is found in habitats with a mixed intermediate fodder quality and supply, such as that in the Kruger National Park.  Here territorial behaviour is permanently maintained, territories ranging from 35-60 ha.  Adult rams aggressively defend their territories but confrontations rarely result in serious injury.  However, up to 50% of sub-adult rams are killed by dominant rams.

The home ranges of non-territorial common reedbuck are relatively small and are seldom larger than 100 ha.  Common reedbuck do not migrate seasonally but, on occasion, might move a distance of up to 80 km in search of a new home range when a habitat becomes unsuitable.

Management

Due to the high mortality of young rams in a population, a game manager should limit their numbers to a minimum and allow only a few replacement rams to develop.  An example of population growth was seen in the Underberg district of KwaZulu-Natal where a population of 150 common reedbuck was established on a 1 000 ha land.  After four years of growth the population had dispersed over an area of 200 000 ha.  As the proportion of suitable habitat within the initial 1 000 ha was not given, it was not possible to calculate the optimal animal density.  However, the rate of dispersal indicates that the initial density of 3-6 ha/animal must have been close to optimal.  The recommended density for maximum production in optimal habitat is 5 ha/animal with a mating ratio of 1 ram : 3.5 ewes.  It is important to take into consideration that this calculation must be made using the area of optimal habitat and not the size of the entire farm.  The mosaic nature of suitable common reedbuck habitat makes its suitability the most crucial parameter affecting population density and distribution range and is more important than feeding quality and quantity.

Due to its low levels of activity, the meat of common reedbuck is very good, soft and fine- textured.

Information Table

Common Reedbuck information table
Characteristic
Ram
Ewe
Adult body weight
kg
60-80
40-60
Adult shoulder height
cm
105
95
Expected longevity
years
9 (16.8 in captivity)
9
Age of sexual maturity
months
?
10-14
Age of social adulthood (1st mating)
years
4
1.5
Gestation
days

220 - 230
1st lamb born at
years

2.1-2.5
Lambing interval
months

9-12
Post maturity age (last mating)
years
8
9
Rutting season
Year round
Lambing season

Year round

Weaning age months
3.5
Gender ratio: Natural (all ages)
1
1
Gender ratio: Production (all ages)
1
2.5
Mating ratio: Natural (adults)
1
2.2
Mating ratio: Production (adults)
1
3.5
Calf birth ratio11
Re-establishment: Absolute minimum number needed
3
2
Re-establishment: Smallest viable population size
3
4
Spatial Behaviour: home range
ha
50-100
50-135
Spatial Behaviour: territory range
ha
35-60
35-60
Large stock grazing unit (adult):
Dietary ratio (Grass):
LSU
0.21 per animal
(95% of diet)
0.21 per animal
(95% of diet)
Browsing unit (adult):
Dietary ratio: (browse):
BU
0.5 per animal
(5% of diet)
0.5 per animal
(5% of diet)
Maximum stocking load
5 ha per animal (at 500-800 mm annual rainfall)
Minimum habitat Size Required
ha
70
Annual population growth
18-25% (mean 12%)
Optimal annual rainfall
500-800mm
Optimal vegetation structure:
Grass height:
Woody canopy cover:

45-200 cm
5-30%

Bibliography

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Berger, LR, & Brink J, 19  , An atlas of southern African mammalian fossil bearing sites – late Miocene to late Pleistocene.
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IUCN SSC Antelope Specialist Group 2008. Redunca arundinum. In: IUCN 2009. IUCN Red List of Threatened Species. Version 2009.2. <www.iucnredlist.org>.
Jungius, H. 1971. The biology and behaviour of the reedbuck Redunca arundinum Boddaert, 1785 in the Kruger National Park. Mammalia Depicta.
Jungius, H, 1971, Studies on the food and feeding behaviour of the reedbuck in the Kruger National Park. Koedoe 14:65-97.
Kingdon, J, 1989. East African Mammals; An atlas of evolution in Africa – Bovids, Vol 111C, University of Chicago Press, Chicago.
Lynch, C. D. and Watson, J. P. 1990. The mammals of Sehlabathebe National Park, Lesotho. Navorsinge van die Nasionale Museum, Bloemfontein 6(12): 523-554.
Nowak, RM, 1999. Walker's Mammals of the World 6th edn. Johns Hopkins University Press, Baltimore.
Rowe-Rowe, DT, 1983. Habitat preferences of five Drakensberg antelopes. S.Afr. J. Wildl. Res. 13;1-8.
Rowe-Rowe, D. T. 1994. The ungulates of Natal. Natal Parks Board, Pietermaritzburg, South Africa.
Skead, CJ, 1987. Historical Mammal Incidence in the Cape. Vol 1 & 2, Government Printer, Cape Town.
Skinner, JD, & Chimba CT, 2005. The Mammals of the Southern African Subregion, 3rd edn. Cambridge University Press, Cambridge.
Smithers, RHN, 1983. The Mammals of the Southern African Subregion, 1st edn. University of Pretoria, CTP Book Printers, Cape Town.
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Wikipedia Encyclopedia, 2010. Redunca http://en.wikipedia.org.

Wilson, DE & Reeder, DM, 1993. Mammal Species of the World, 2nd edn. Smithsonian Institution Press, Washington.

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