The Riverine Rabbit according to MammalMAP
The Riverine Rabbit (Bunolagus monticularis) is the 13th most endangered mammal in the world and gets its common name from its strict preference for inhabiting the dense vegetation that grows along the seasonal rivers that flow through the Central Karoo in South Africa.
The Riverine Rabbit is characterised by a distinct white ring around each eye as well as a dark line running from the corner of its mouth over its cheek, giving it an almost eerie Joker-like smile. The upper-parts of the rabbit are dark brown with black speckles, whilst the under-parts are light brown. The belly and throat sports cream coloured fur. The length of the head and body is 33.7-47.0 cm long and it weighs approximately 1.0-1.5 kg. The riverine rabbit is predominantly nocturnal and feeds predominantly on wildflowers that grow on the floodplains in the Karoo.
The existence of this critically endangered (IUCN Red List of Threatened Species) mammal is threatened by continuing habitat loss, since the alluvial flood plains are ideally suited for agricultural purposes, with only a few hundred individuals remaining in the wild (Hughes et al., 2007). On top of this, these rabbits have long generation times and only produce 1-2 offspring per year, with the numbers of breeding pairs severely declining in the last 70 years (Duthie, 1989).
Conservation efforts concerning this EDGE species is coordinated by the Riverine Rabbit Programme (Drylands Conservation Programme) of the Endangered Wildlife Trust (EWT). The vision of these conservation bodies is to maintain a healthy and functional Karoo ecosystem that can support a stable population of riverine rabbits as well as other biodiversity in the region, whilst at the same time uplifting the socio-economic status of the local communities and land-owners.
Bunolagus monticularis is endemic to South Africa. It has an extremely limited geographic range, found only in the central and southern regions of the Karoo Desert of South Africa's Cape Province (Chapman and Flux, 1990).
Biogeographic Regions: ethiopian (Native )
Bunolagus monticularis is easily identified by the black stripe running from the corner of its mouth over its cheek, a brown woolly tail, cream-colored fur on its belly and throat, and a broad, club-like hind foot. Its tail is pale brown with a tinge of black toward the tip. Its coat is soft and silky and its limbs are short and heavily furred (Nowak, 1997). Male riverine rabbits weigh approximately 1.5 kg while females weigh about 1.8 kg (Duthie, 1987).
Range mass: 1.5 to 1.8 kg.
Range length: 337 to 470 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: female larger
Bungolagus monticularis lives in dense riverine scrub along the seasonal rivers in the central Karoo Desert in the Cape Province of South Africa (Mills, 1997).
Habitat Regions: tropical ; terrestrial
Terrestrial Biomes: desert or dune ; scrub forest
Other Habitat Features: riparian
Habitat and Ecology
STATE OF HABITAT: Fragmented.
CHANGE IN HABITAT SIZE: Decreasing in area.
RECENT CHANGE: 51%-80%.
DURING HOW MANY YEARS? 100.
PREDICTED DECLINE IN HABITAT <20%.
PREDICTED DURATION OF DECLINE: 100.
PRIMARY CAUSE OF CHANGE: Cultivation and livestock farming.
CHANGES IN QUALITY: Decrease in quality.
NOTES ON QUALITY: livestock and cultivation.
HABITAT NOTES: Habitat not being minimally transformed at present. subpopulations isolated from each other by jackal-proof fencing and severe land transformation through agricultural practices.
Generation length for this species is two years (Collins et al. 2004). This species has a single litter per year with 1-2 young per litter (Duthie 1989). Reproductive periodicity occurs from August through May (Duthie and Robinson 1990). Gestation time is 35-36 days (Duthie 1989). Longevity in captivity is five years (Collins et al. 2003). Home range is 12 ha (Duthie 1989). Total length ranges from 33.7-47.0 cm (Nowak 1991).
Bunolagus monticularis is predominantly a browser. It eats riparian vegetation found along seasonal rivers in the Karoo Desert. This includes salt-loving plants such as Salsola and Lycium, as well as flowers and leaves from boegoe and ink bushes (Mills, 1997). Grasses are included in the diet when these are available in the wet season. Bunolagus is also known to eat its day-time droppings which are soft, taken directly from the anus, and swallowed. By doing this, it takes in vitamin B, produced by bacteria in the hind gut, and minerals such as calcium and phosphorus are recycled (Burton, 1987).
Plant Foods: leaves; wood, bark, or stems; flowers
Other Foods: dung
Primary Diet: herbivore (Folivore ); coprophage
Bungolagus monticularis has a limited ecosystem role. The riverine vegetation it feeds on is known to bind soil and regenerates as the rabbit feeds on it. This means that the Riverine rabbit's feeding habbits indirectly prevents the soil from being washed away in floods (Duthie, 1987).
Bunolagus is capable of jumping over one meter high bushes when being pursued by a predator. To escape predatation, it remains nocturnal, spending the day resting in a form, a shallow scrape made in the soil, under a Karoo bush (Smithers, 1986).
- black eagles (Ictinaetus malayensis)
- other carnivores (Carnivora)
Anti-predator Adaptations: cryptic
This list may not be complete but is based on published studies.
Life History and Behavior
Perception Channels: tactile ; chemical
Bunolagus monticularis has never been kept in captivity. There is no information on its lifespan in the wild or in captivity currently available (Chapman and Flux, 1990).
Lifespan, longevity, and ageing
Bunolagus monticularis is one of the rarest mammals in the world and very little is known about its reproductive behavior other than it has a polygynous mating system. Males mate with more than one female.
Mating System: polygynous
Little is known about the life cycle of Bunolagus monticularis. Females nest in subterranean chambers and produce a single offspring per year, which is an unusually low breeding rate for rabbits (Avery, 1997). Young are born helpless and blind, and they rely on their mothers for the first part of their lives. The young weigh about 40-50 grams when born (Smithers, 1986).
Breeding season: Breeding occurs from August through May.
Range number of offspring: 1 (low) .
Average number of offspring: 1.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
Average birth mass: 45 g.
Average number of offspring: 1.
The young are altricial, underdeveloped at birth, and are born blind and hairless. They spend the first part of their lives with their mothers until they are able to move independently. Bunolagus monticularis is the only African rabbit that prepares an underground shelter for its young. This nest is 10-15 cm in diameter, 25 cm long, and lined with grass and fur (Nowak, 1997).
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)
Molecular Biology and Genetics
Statistics of barcoding coverage: Bunolagus monticularis
Public Records: 0
Specimens with Barcodes: 1
Species With Barcodes: 1
Bunolagus monticularis is an endangered species. The most devastating threat to the riverine rabbit is the loss of its habitat. This habitat is limited to the alluvial floodplains of seasonal rivers in the central Karoo. These flood plains, only 100 - 200 m wide, are formed when the rivers overflow during floods, and deposit silt on their banks(Duthie, 1987). This soil is very good for cultivation compared with other soils found in the dry Karoo. Over the past 50 years, more than two-thirds of its habitat has been ploughed over for this purpose. Other threats to its survival include overgrazing and hunting. Overgrazing of riverine habitat opens up cover that it needs for shelter and to escape predation.
The only way to secure the long term survival of Bunolagus monticularis is to protect its natural habitat. The Dept. of Environment and Cultural Affairs has started a project which encourages farmers to form conservancies for this rabbit. Some Karoo farmers have taken this step and declared their farms Natural Heritage Sites to protect the riverine habitat and rabbit (Duthie, 1987).
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: critically endangered
IUCN Red List Assessment
Red List Category
Red List Criteria
Erratum: Since this assessment was published in 2008, it has been confirmed that the quantitative analysis for this species considered only part of the global population. Since this analysis did not consider the entire global population for this species, it does not support the use of criterion E for this assessment. Therefore criterion E has now been removed from this assessment.
- 2008Critically Endangered
- 2003Critically Endangered(IUCN 2003)
- 2003Critically Endangered
- 1994Endangered(Groombridge 1994)
- 1990Endangered(IUCN 1990)
- 1988Endangered(IUCN Conservation Monitoring Centre 1988)
- 1986Endangered(IUCN Conservation Monitoring Centre 1986)
Relevance to Humans and Ecosystems
The riverine habitat of Bunolagus monticularis provides many benefits for farmers. The riverine vegetation that the rabbit feeds on, causing this vegetation to regenerate, binds the soil and prevents it from being washed away in floods. Also, this vegetation promotes filtration of rainwater to groundwater, which is a benefit for the farmer who uses windmills to draw up water for his livestock (Burton, 1987). Indirectly, the habitat of Bunolagus monticularis helps humans in farming and can only be sustained if this rabbit continues to feed on this vegetation.
The riverine rabbit (Bunolagus monticularis), also known as the bushman rabbit or bushman hare, is one of the most endangered mammals in the world, with only around 250 living adults. This rabbit has an extremely limited distribution area, found only in the central and southern regions of the Karoo Desert of South Africa's Cape Province. It is the only member of the genus Bunolagus.
The Riverine rabbit has the general appearance of most rabbits, but the ears and body are longer. It typically has a black stripe running from the corner of the mouth over the cheek, and a white ring around each eye. It has a brown woolly tail, cream or grayish-colored fur on its belly and throat, and a broad, club-like hind foot. It has a dental formula of 2/1, 0/0, 3/2, 3/3, like other rabbits, with a total of 28 teeth.
It is found in only a few places in the Karoo Desert of South Africa's Cape Province, none of them being a protected area. As its name suggest, the Riverine rabbit prefers to occupy river basins and very particular shrubland. The rabbit feeds on the dense shrubland and the soft soil allows for it to create vast burrows and dens for protection, brooding young, and thermoregulation.
Riverine rabbits feed on their favourite foods, flowers, grasses, leaves at night, and rest in forms during the day. A form is a shallow scrape made in the soil under a bush. Two types of droppings are produced. While active during the night the rabbit will produce hard droppings, and during the day droppings are soft, taken directly from the anus, and swallowed. In this way the riverine rabbit obtains vitamin B, produced by bacteria in the hind gut, and minerals such as calcium and phosphorus are recycled.
The Riverine rabbit participates in a polygamous mating style, where the males mate with more than one female. Like other rabbits, it bears its young underground for protection. This because the single offspring that the rabbit produces is born altricial, or bald, blind, and helpless, and weigh only from 40 to 50 grams. However, the Riverine rabbit is the only African rabbit that bears its young underground. The helpless offspring with stay with the mother until it is capable of living on its own and fend for itself. The low breeding rate of only one offspring per year is not like most other rabbits and coincides with the issues of repopulating this endangered species.
- Hoffman, R. S.; Smith, A. T. (2005). "Order Lagomorpha". In Wilson, D. E.; Reeder, D. M. Mammal Species of the World (3rd ed.). Johns Hopkins University Press. p. 194. ISBN 978-0-8018-8221-0. OCLC 62265494.
- Collins et al. (2003). Bunolagus monticularis. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 2006-05-11. Database entry includes justification for why this species is critically endangered
- Macdonald, D (2001). The New Encyclopedia of Mammals. Oxford University Press. ISBN 9780198508236.
- Awaad, Rania (2007). "Animal Diversity Web". Animaldiversityweb.org. University of Michigan. Retrieved 7 December 2014.
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