Animal Info - Riverine Rabbit

(Other Names: Boshaas, Buschmannhase, Bushman Rabbit or Hare, Deelfontein Hare, Doekvoetjie, Pondhaas, River Hare, Vleihaas)

Bunolagus monticularis (Lepus m.)

Status: Critically Endangered

1. Profile (Picture)
2. Tidbits
3. Status and Trends (IUCN Status, Countries Where Currently Found, Population Estimates, History of Distribution, Threats and Reasons for Decline)
4. Data on Biology and Ecology (Weight, Habitat, Gestation Period, Birth Season, Birth Rate, Early Development, Diet, Behavior, Social Organization, Density and Range, Minimum Viable Population)
5. References

Profile

Pictures: Riverine Rabbit #1 (21 Kb JPEG) and Riverine Rabbit #2 (24 Kb JPEG) (Riverine Rabbit Cons. Proj.); Riverine Rabbit #3 (19 Kb JPEG); Riverine Rabbit #4 (37 Kb) (Spec. Cons. Found.)

The riverine rabbit weighs up to 1.9 kg (4.2 lb). Distinguishing marks include a distinctive white ring around each eye and a black stripe running from the corner of its mouth over its cheek. Found in dense riverine scrub along the seasonal rivers in the central Karoo Desert in the Cape Province of South Africa, its diet mainly consists of flowers and leaves; grasses are included in the wet season. These rabbits are nocturnal and solitary, with a polygamous mating system and an unusually low breeding rate (for a rabbit).

The riverine rabbit is endemic to the central Karoo Desert of South Africa's Cape Province. It was seen several times between 1902 and 1948, but it was then not seen again until 1979. Surveys in 1989 suggested that it survived only in the dense, discontinuous vegetation in the districts of Victoria West, Beaufort West and Frazerburg, an area of approximately 86 sq km (33 sq mi). As of 2001, it was thought to occur in river catchments in the semi-arid south central Karoo between Beaufort West and Williston, and Sutherland and Victoria West. It is found only on private farmland in riverine vegetation along seasonal river courses.

Conversion of habitat for agriculture has been the major threat to the riverine rabbit. Upwards of 60% of the original riparian vegetation where it is found has been converted to cultivation. While the extent of this habitat loss is significant it is currently static. Other threats include: habitat loss due to firewood collecting and heavy grazing pressure by sheep, traditional hunting with dogs, predation from uncontrolled dogs roaming in the veldt, mortality due to traps such as the serrated steel-jawed gin trap, and construction of dams which dry up the rivers.

Tidbits

*** The riverine rabbit is one of the world's rarest mammals.

*** The riverine rabbit has an unusually low (for rabbits) breeding rate of only 1-2 young/year.

*** Rabbits have traditionally not received much attention in Africa. The riverine rabbit has been a notable exception. Conservation efforts by the Wildlife Society of Southern Africa and the South African Nature Foundation, in concert with research activities, have done much to draw attention to its plight. A number of governmental and non-governmental organizations have joined together in the Riverine Rabbit Conservation Project to carry out important conservation work.

*** A riverine rabbit awareness program among the farmers of the central Karoo has been instituted. Since the rabbit is found only on privately owned farms, its survival depends on the willingness of landowners to adopt farming methods to reduce over-grazing and other harmful practices in the sensitive riverine habitat. Some Karoo farmers have declared their farms Natural Heritage Sites to protect the riverine habitat and rabbit. (Collins 2001, Yeld 1999)

*** Rabbits (belonging to many different genera) vs. Hares (all in the genus Lepus): The major differences between rabbits and hares include: 1.) their methods in avoiding predators (rabbits hide in dense vegetation or burrows; hares have longer legs and try to outrun predators), and 2.) the characteristics of their young at birth (newborn rabbits ("kittens") are born naked and with their eyes closed; newborn hares ("leverets") are better developed - their eyes are open and they can move around with some degree of coordination) (Macdonald 2001).

Status and Trends

IUCN Status:

1980's - 1994: Endangered
1996 - 2002: Endangered (Criteria: B1+2c)
2004: Critically Endangered (Criteria: C2a(i)) (Population Trend: Decreasing) (IUCN 2004)

Countries Where the Riverine Rabbit Is Currently Found:

2004: Occurs in South Africa (Northern Cape; Western Cape) (IUCN 2004).

Population Estimates:

[Note: Figures given are for wild populations only.]

WORLD (South Africa)
- 1989: It was estimated that the remaining habitat potentially could support 1435 rabbits but that the actual surviving population probably was much smaller. (Nowak 1999)
- 1995: Fewer than 1000 (Focus 1995b)
- 1996: Probably well below 1000 animals (Stuart & Stuart 1996)
- 2003: Less than 250 mature individuals (IUCN 2004)
- 2005: About 250 adults (Flux 2005)

History of Distribution:

The riverine rabbit first became known to Western science in 1902. It is endemic to the central Karoo Desert (31 deg 22 min South, 22 deg East) of South Africa's Cape Province. It was seen several times between 1902 and 1948, but it was then not seen again until 1979. In 1987 it was reported to occur around the Rhinoceros and Fish Rivers of the Karoo in two separate populations: near Calvinia and near Deelfontein. Surveys in 1989 suggested that it survived only in the dense, discontinuous vegetation in the districts of Victoria West, Beaufort West and Frazerburg, an area of approximately 86 sq km (33 sq mi).

As of 2001, it was thought to occur in river catchments in the semi-arid south central Karoo between Beaufort West and Williston, and Sutherland and Victoria West. It is found only on private farmland in riverine vegetation along seasonal river courses. (Ahlmann 2001, Cape Nature Conservation)

Distribution Map #1 (14 Kb GIF) (African Mammals Databank 2004)
Distribution Map #2 (25 Kb JPEG) (Spec. Cons. Found.)
Distribution Map #3 (60 Kb JPEG) (Riverine Rabbit Cons. Proj.)

Threats and Reasons for Decline:

Habitat loss due to conversion to agriculture has been the major threat to the riverine rabbit. The alluvial floodplain soil of its habitat is very good for cultivation compared with other soils found in the dry Karoo. A recent calculation from aerial photographs of the central Karoo indicates that, in the region where the rabbit has occurred, upwards of 60% of the original riparian vegetation has been converted to cultivation. The conversion has been attributed to a now largely defunct scheme to cultivate wheat on the banks of the rivers in the region which, by 1950, had failed due to lack of irrigation water. While the extent of habitat loss is significant it is currently static. (Chapman & Flux 1990, Collins 2001)

Other threats include: habitat loss due to firewood collecting and heavy grazing pressure by sheep, traditional hunting with dogs, predation from uncontrolled dogs roaming in the veldt, mortality due to traps such as the serrated steel-jawed gin trap, and construction of dams which dry up the rivers. (Ahlmann 2001, 2002)

Data on Biology and Ecology

Weight:

The riverine rabbit weighs 1.4 - 1.9 kg (3.1 - 4.2 lb).

Habitat:

The riverine rabbit lives only in dense riverine scrub in the alluvial floodplains of the seasonal rivers in the central Karoo Desert. It is restricted to riverine scrub of 0.5 - 1 m (1.6 - 3.2') in height and to areas with soil types that allow stable burrows to be constructed. (Avery 1988, Stuart & Stuart 1996)

The riverine rabbit is one of the species that live in the Cape Floristic Region Biodiversity Hotspot (Cons. Intl.).

Gestation Period:

35 - 36 days (Stuart & Stuart 1996).

Birth Season:

Births occur during August through May.

Birth Rate:

One, rarely two per year.

Early Development:

A newborn riverine rabbit is altricial. It is reared in a fur- and grass-lined burrow.

Diet:

The riverine rabbit is predominantly a browser, eating flowers and leaves from shrubs. Grasses are included in the diet when these are available in the wet season.

The riverine rabbit produces two types of droppings. At night, when the rabbit is active, hard pellets are deposited. During the day, droppings are soft and are reingested by the rabbit. In this way the riverine rabbit obtains vitamin B, produced by bacteria in its hind gut, and minerals such as calcium and phosphorus are recycled. (Collins 2001)

Behavior:

The riverine rabbit is nocturnal, feeding at night and resting during the day in forms, which it scrapes out under a bush.

It is the only African rabbit where the female prepares an underground burrow for her young. This nest is lined with grass and fur. (Nowak 1999)

Social Organization:

The riverine rabbit is solitary with a polygamous mating system. Males and females each maintain home ranges which are exclusive with regard to members of their own sex, with a male's home range overlapping with the home ranges of several females.

Density and Range:

Density: Two censuses conducted in sections of the typical habitat have yielded densities of 6.4 and 16.6 individuals/sq km (16.6 and 43.0 individuals/sq mi).

Home range: The female home range = 12.9 hectares (32 acres) +/- 43%. The male home range = 20.9 hectares (52 acres) +/-14%.

(Chapman & Flux 1990)

Minimum Viable Population:

Minimum Viable Population Density: 6.4 individuals/sq km (16.6 individuals/sq mi) (Silva & Downing 1994)

References

African Mammals Databank 2004, Ahlmann 2001, Ahlmann 2002, Avery 1988, Burton & Pearson 1987, Chapman & Flux 1990, Collins 2001, Collins et al./IUCN 2003a, Flux 2005, IUCN 2004, Cons. Intl., Focus 1995b, IUCN 1994, IUCN 1996, IUCN 2000, IUCN 2003a, Kingdon 1997, Macdonald 1984, Macdonald 2001, Nowak 1999, Nowak & Paradiso 1983, Riverine Rabbit Cons. Proj., Silva & Downing 1994, Spec. Cons. Found., Stuart & Stuart 1996, WWF Wild World, Yeld 1999

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Last modified: June 18, 2006;