The Riverine Rabbit - A Monotypic Species
The Riverine rabbit is the only representative of its genus Bunolagus. It is one of the most endangered mammals in the world today. Its full scientific name is Bunolagus monticularis and it has the common names of Bushman rabbit or Bushman hare. However it is not a hare. The offspring of the hare is born with its eyes open and some ability to coordinate its long limbs. The hind legs are longer and it is more likely to try to outpace its predators than the rabbit, which is more inclined to try to hide.
This monotypic genus with just the one species is not alone in its uniqueness. There are a great number of animals that are the sole representatives of their genera, including the moose, numbat, rock hyrax, giraffe and pronghorn. Not all are endangered. The impala is very common with several million roaming the savannahs of Africa.
The Riverine rabbit is found only in Cape Province in South Africa. Isolated pockets exist in the central and southern areas of the Karoo Desert and none of its habitat lies in protected areas such as national parks or nature reserves. Following research in 2001, it is now believed to exist only along seasonal river courses in thick river vegetation in the south central Karoo. The flood plains of the seasonal Karoo rivers and streams are fertile but agriculture is also practised in these areas, creating substantial competition of the rabbit.
The Riverine rabbit is an elegant creature with very long ears and a soft, silky coat. It may reach between 34 and 37cm long with males weighing about 1.9kg. Females are slightly smaller.
The limbs are short and covered with very thick fur. The dorsal surfaces are dark brown and flecked with black. The throat and belly areas are cream. There is a distinctive dark brown stripe along the lower jaw from the corner of the mouth towards the base of the ear. Behind the ears on the neck is a red-brown patch and a white ring circles each eye. It has a brown tail. The hind feet are broad and club-like in shape.
This is a solitary creature and nocturnal in its habits. During the day, it rests in shallow depressions under the cover of bushes.
The Riverine rabbit mostly browses on flowers and leaves. It will also eat grass during the wet season. The Riverine produces two types of faeces. During the night, when the rabbit is active, the droppings are hard and pelleted. During the day, the faeces are soft and eaten straight from the anus by the rabbit. Many other rabbit species practise this habit which is called coprophagy. There is vitamin B in the faeces, this having been produced by bacteria in the hind gut. The vitamin B is absorbed during this second period of digestion and additional calcium and phosphorous is extracted.
The males have a large home range and will mate with every female in that range. Only one or two young are born each year. The Riverine is the only African rabbit to make an underground nest. The doe lines the nest with grass and fur. The gestation period is 35 days. The kitten is born blind, helpless and without fur. It stays with its mother for some time before heading off to lead an independent life.
There are a number of problems facing the Riverine rabbit. Continual cultivation of the flood plains makes construction of stable breeding burrows difficult for the rabbit as does the removal of natural vegetation along the rives. The habitat is further degraded and fragmented by over-gazing by domestic livestock. Gin traps and hunting with dogs account for many deaths of rabbits which are regarded as bush food by farm workers.
Other predators include feral dogs and eagles, particularly the local black eagle which is relatively common in the area. With an estimated 200 or fewer left, there is little time to turn the clock back for the Riverine rabbit.
The Riverine rabbit was not sighted at all between 1948 and 1979. Since a workshop held in 2000, South Africa and the world has become much more aware of the plight of the Riverine rabbit. It is found mostly on private farmland and the goodwill of the owners is vital to the survival of the species. Some of the farmers have declared their farms Natural Heritage Sites and the Riverine Rabbit Working Group now coordinates all conservation methods and efforts. A Working Group set up in 2003 by the Endangered Wildlife Trust has sought to establish an ecosystem to support a stable population of Riverine rabbits.
Socioeconomic conditions in the area are being addressed to encourage voluntary cooperation with the Working Group in achieving its aims.