When people think of threatened species, they tend to think of big and “spectacular” species like whales, tigers, rhinos, or pandas. It is true that many large mammal species, except us (we are quite large mammals too, after all), are threatened – we are pushing everything else out, as our population keeps growing. But there are also many smaller mammals that are threatened too. One such species is the Riverine Rabbit Bunolagus monticularis of South Africa. It is also known as a Bushman’s Hare, and in Afrikaans, Doekvoet (‘cloth foot’, after its soft and fluffy feet) or Pondhaas (‘pound hare’, because in the 1930’s farmers were rewarded for a specimen with a payment of one Pound).
Though it is called a rabbit, in some ways it is more like a hare. For those who don’t know, the primary differences between rabbits and hares in Britain and Europe are:
1) Hares are longer and lankier in body shape than rabbits, and they have longer ears.
2) Rabbits dive into shelters when threatened, whereas hares will usually freeze or run away.
3) Hares give birth in an open hollow called a ‘form’ to precocial young (called leverets), precocial species are those in which the young are relatively mature and mobile from the moment of birth. Rabbits give birth in burrows, to young (called kittens) that are blind and helpless, needing a few days before they become mobile and more independent (i.e. altricial).
These guidelines work for rabbits and hares in Europe, where only a couple of species of lagomorphs (the group to which Rabbits and Hares belong) occur. In the rest of the world, however, there are lagomorphs that can’t be clearly defined as either being a rabbit or a hare. The Riverine Rabbit is one of these. Unlike a rabbit, it has long ears, and unlike a hare, it gives birth to helpless kittens in an underground burrow dug by the female. In body build, it is not lanky like hares, having fairly short hind legs, and when fleeing it has a rather scurrying gait. There are a few other such rabbit-hares in the world. These are sometimes considered ‘relic species’ – evolutionary holdovers, similar to the early ancestors of both hares and rabbits, before they became distinct from each other.
The Riverine Rabbit is beautiful. It has a reddish brown coat with grey grizzling on its back and creamy yellow fur on its belly. Its eyes are outlined in white, and there are white lines along the front edges of its ears too. Most characteristically, it has a prominent black stripe along each cheek. The Riverine Rabbit is one of the most distinctively marked of all rabbits or hares. It is only trumped by the two southeast Asian species of Striped Rabbit comprising the genus Nesolagus (both extremely rare and threatened).
Riverine Rabbits are fairly small, weighing in at 1.4-1.9 kg. Females are a bit heavier than males. These little rabbits are nocturnal. They come out at night to feed on grass – when it’s available (only after good rains) – or the foliage of saltbush, buchu, honey thorn or ink bush shrubs. During the day, they rest in forms (scraped-out hollows) under bushes, keeping cool as the semi-desert heats up.
Like other rabbits, they eat their own droppings. And, did you know that they produce two different kinds of droppings? At night, they produce hard droppings, which they don’t eat. But he ones they produce during the day are soft, and these are the ones they eat. These droppings are rich in the minerals calcium and phosphorus, and B-vitamins. These vitamins are produced by bacteria that live in the rabbit’s hind-gut, a kind of mutually-beneficial symbiosis.
The Riverine Rabbit has a very localized distribution. It only occurs in the valleys of a number of non-perennial rivers in the Karoo region of South Africa, within the Renosterveld and Succulent Karoo vegetation biomes. The rivers in the Karoo only flow periodically, but when they do, they sometimes overflow their banks along broad alluvial plains, where they deposit fertile silty soil.There was an attempt to turn these fertile river valleys of the Karoo into farmland and unfortunately about 60% of this riverine habitat has been destroyed – converted into wheat fields. But this region is not really viable for crop agriculture, it is just too dry; plenty of irrigation is needed and in this forbidding area it is not practical.
The rabbits of course can’t easily find new homes. They are dependent on the dense shrubs that grow along the rivers – on the open plains they will be too exposed, and the soil is too rocky for them to dig their burrows in. They can only live along those narrow, densely vegetated strips with soft, silty soils – only one or two hundred meters wide – that fringe the rivers.
Even in areas where the river valleys haven’t yet been turned into farmland, the rabbits suffer from other threats. People still cut down bushes and trees along the river for firewood, and many areas are overgrazed by sheep and other livestock. This causes soil erosion with a further loss of food and shelter plants. Rabbits are sometimes hunted with dogs – or caught by stray dogs. They are also caught in traps set for small game or for predators. Also, some of the rivers have been dammed, causing reduced flow of water in the lower reaches, leading to die-off of the riverine vegetation. And fences, which the rabbits can’t easily navigate, also cause problems for gene flow among rabbit populations.
Although the saying goes “breeding like rabbits”, Riverine Rabbits don’t! In fact, a doe usually only gives birth to 1 or 2 young per year. This is a typical life history strategy of a species with limited available habitat/resources. Many species of mammals or birds that live on islands, where resources are also limited, are the same. They only have a few young at a time and breed infrequently. But, when threats from outside, like humans, enter their habitat it makes these species extremely vulnerable.
All these various threats have caused a serious decline in Riverine Rabbit numbers. Estimates suggest that originally its habitat could have supported about 1 500 individuals, but now its population has shrunk to perhaps only 500 or so individuals in the wild! This makes it one of the 50 rarest mammal species in the world (that we know of)!
Fortunately, there have been projects over the past decade or two to inform farmers of this unique mammal. Several farms have been declared ‘conservancies’, with the farmers pledging to protect riverine vegetation, or actively working to re-vegetate denuded riverbanks, and to reduce other threats like overgrazing or hunting. The main project to coordinate all conservation efforts, is the Drylands Conservation Project of the Endangered Wildlife Trust. The main thrust is to promote a sense of ‘stewardship’ in land owners on whose property these rabbits occur. These little mammals are ecologically valuable, and are indicators of a healthy environment.
The rabbits themselves have proved to be resilient, and recently a few new populations have been discovered, such as at Anysberg Nature Reserve in 2014, and the Baviaanskloof in 2019. We still have much to learn about Riverine Rabbits. Without adequate knowledge, our conservation efforts are hamstrung. But new technology is helping, like camera traps that are being used to discover new populations and monitor existing ones. You can help too! By uploading any photos you might have to MammalMAP at http://vmus.adu.org.za/
