Overview

Brief Summary

Biology

Differing from the usual rapid breeding of most rabbit species, the riverine rabbit produces just one kitten a year. In a polygynous mating system, males make use of their large home ranges to mate with every female in their territory (2). Between August and May (3), the females will make a nest in a burrow lined with grass and fur, and blocked with soil and twigs (4). They give birth to a helpless, blind and hairless kitten 35 days after mating (5). This underdeveloped offspring will remain will its mother for some time before dispersing (2). The riverine rabbit is nocturnal, spending the night feeding on flowers, leaves and grasses, and the day in shallow depressions under bushes, hiding from predators such as black eagles. At night the droppings are firm, but during the day they are soft and are immediately eaten after deposition. This behaviour is known as coprophagia and occurs in rabbits as their digestive system is basic, and re-ingestion allows further extraction of calcium and phosphorous, as well as the absorption of vitamin B that is produced by the bacteria of the hind gut during the initial ingestion (2).
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Description

This elegant rabbit is one of the most endangered terrestrial mammals in Southern Africa. It has very long ears, a soft and silky coat and a uniformly brown, woolly tail. A distinctive black stripe runs from the corner of the mouth over the cheeks (2), and it has white rings around the eyes (3). The belly and throat are cream in colour and the short limbs have particularly thick fur (2).
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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.

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Distribution

Range Description

This species is endemic to the central Karoo region of South Africa. The extent of occurrence is 101-5,000 km² and area of occupancy is 11-500 km².
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Geographic Range

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 )

  • Chapman, , Flux. 1990. Rabbits, Hares and Pikas - Status Survey and Conservation Action Plan. Gland, Switzerland: IUCN/SSC.
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Range

Endemic to South Africa, the riverine rabbit is found in the semi-arid Central, Upper, Ceres, and Klein Karoo regions (2).
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Physical Description

Morphology

Physical Description

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

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Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
The Riverine Rabbit inhabits dense riparian growth along the seasonal rivers in the central Karoo (Nama-Karoo - shrubland). Occurs specifically in riverine vegetation on alluvial soils adjacent to seasonal rivers. The habitat is highly fragmented and transformed. Studies show the habitat to be 67% fragmented in certain areas that can be considered representative of the entire distribution.

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).

Systems
  • Terrestrial
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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

  • Mills, G., L. Hes. 1997. The Complete Book of South African Mammals. South Africa: Struik Publishers.
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Inhabits areas alongside seasonal rivers with a thick cover of riverside vegetation (1).
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Trophic Strategy

Food Habits

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

  • Burton, , Pearson. 1987. Rare Mammals of the World. Lexington, MA, USA: Stephen Greene Press.
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Associations

Ecosystem Roles

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).

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Predation

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).

Known Predators:

Anti-predator Adaptations: cryptic

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Known predators

Bunolagus monticularis is prey of:
Falconiformes

This list may not be complete but is based on published studies.
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Life History and Behavior

Life Expectancy

Lifespan/Longevity

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).

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Lifespan, longevity, and ageing

Observations: Knowledge regarding the longevity of these animals is limited. One wild born specimen was about 4.8 years of age when it died in captivity (Richard Weigl 2005).
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Reproduction

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); 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)

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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage: Bunolagus monticularis

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Specimens with Barcodes: 1
Species With Barcodes: 1
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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
CR
Critically Endangered

Red List Criteria
C2a(i)

Version
3.1

Year Assessed
2013

Assessor/s
South African Mammal CAMP Workshop

Reviewer/s
Smith, A.T. & Johnston, C.

Contributor/s

Justification
No subpopulation is estimated to contain more than 50 individuals, and these subpopulations appear to be isolated due to anthropogenic barriers to dispersal. Quantitative analysis using VORTEX 3.1 showed that the probability of extinction in the wild was more than 50% within the next 100 years. (see Erratum below).


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.

History
  • 2008
    Critically Endangered
  • 2003
    Critically Endangered
    (IUCN 2003)
  • 2003
    Critically Endangered
  • 1996
    Endangered
  • 1994
    Endangered
    (Groombridge 1994)
  • 1990
    Endangered
    (IUCN 1990)
  • 1988
    Endangered
    (IUCN Conservation Monitoring Centre 1988)
  • 1986
    Endangered
    (IUCN Conservation Monitoring Centre 1986)
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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

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Status

The riverine rabbit is classified as Critically Endangered (CR) on the IUCN Red List 2004 (1).
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Population

Population
Ref: (Collins et al. 2004). There are less than 90% of mature individuals in one subpopulation. There are 10 subpopulations. There has been a rapid decline of population due to loss of 50-60% of habitat in the past 70 years, this decline has been arrested due to a decrease in cultivation and public awareness and establishment of conservancies. The current population is estimated at less than 250 breeding pairs and is declining. It is estimated that over the last 70 years the population has declined by 60% or more. Population decline of 10% or more is predicted to occur between 2002 and 2022. The population is fragmented, with no subpopulation containing more than 50 individuals. Population densities were estimated at 0.064-0.166/ha (Duthie et al. 1989).

Population Trend
Decreasing
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Threats

Major Threats
Loss and degradation of habitat are the main threats to the species. Over the last century, 50-80% of habitat has been lost as a result of cultivation (mostly in the past) and livestock farming (ongoing). Other threats to the species include hunting (the rabbit is hunted for sport and by farm workers), and accidental mortality in traps set for pest animals on farmlands.
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During the last 100 years, over two thirds of the riverine rabbit's habitat has been lost, and today, only 250 mature riverine rabbits are estimated to exist in the wild. The majority of the land in the Karoo Desert is very unfertile, but the riverine rabbit occupies the flood plains of the seasonal Karoo rivers and its tributaries, which are fertile and have therefore been ploughed extensively in some areas. Removal of the natural vegetation along the rivers and streams prevents the rabbit from constructing stable breeding burrows, due to the loss of the soft alluvial top soils, and from feeding and escaping predation (1). Overgrazing by domestic herbivores also poses a threat to the rabbits' habitat and results in habitat degradation and fragmentation (2). As rabbits and hares are adding to the menu of farm workers, they are shot or trapped with gin traps (1).
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Management

Conservation Actions

Conservation Actions
Bunolagus monticularis is listed as Endangered in the 1986 South African National Red Data Book, and there is a genetic study of the species underway. At the CBSG CAMP South Africa workshop, conservation actions recommended included further research into the life history of this species, management of habitat, wild population management, limiting factors, captive breeding/cultivation, and increased public awareness. The captive breeding/cultivation recommendations include plans for species recovery, education, reintroduction, research, and a management plan workshop. There is currently a coordinated species management program in South Africa.
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Conservation

The Endangered Wildlife Trust's Riverine Rabbit Working Group (EWT-RRWG) was established in August 2003, with the aim of establishing and conserving an ecosystem and socioeconomic conditions in the Karoo that can support a stable population of riverine rabbits. The EWT-RRWG achieves this through surveys, research and monitoring, environmental education and awareness, habitat management and rehabilitation, and conservation stewardship programmes. At present, none of the riverine rabbit habitat is protected, and the species only occurs on private Karoo farmland. Therefore, the establishment of Riverine Rabbit Conservancies is an important aim for the EWT-RRWG. Conservancies are areas established by a voluntary agreement with private landowners who have riverine rabbits and potentially suitable habitat on their properties. So far, three have been established in the Karoo. The conservation and management of riverine rabbit populations and their habitat is outlined in the conservancy constitution, and landowners strictly control or prohibit any hunting with dogs, and the use of gin traps (7). With the EWT-RRWG raising awareness of the riverine rabbit's threatened status, and coordinating conservation efforts, it is hoped that the risk of extinction to this rare species can be reduced.
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Relevance to Humans and Ecosystems

Benefits

Economic Importance for Humans: Positive

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.

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Wikipedia

Riverine rabbit

The riverine rabbit (Bunolagus monticularis), also known as the bushman rabbit or bushman hare, is one of the rarest and most endangered mammals in the world, with probably no more than 400 individuals left. 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.

Identification[edit]

It typically has a black stripe running from the corner of the mouth over the cheek. It has 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. It is a nocturnal species.

Habitat[edit]

It is nowadays found in only a few places in the Karoo, none of them being a protected area. Fraserburg, Sutherland and Victoria West all have small populations.

Behavior[edit]

Riverine rabbits feed on their favourite foods, the boegoe[disambiguation needed] bush and ink bush at night, and rest up in forms during the day. A form is a shallow scrape made in the soil under a bush. Two types of droppings are produced. At night, when the rabbit is active, hard pellets are deposited. 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.

References[edit]

  1. ^ 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. 
  2. ^ 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
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