Red List of South African Species

Alternatively, Explore species
| National Red List categories | Partners |
Critically Endangered (CR)
C2a(i)
Assessors: Kai Collins Christy Bragg Coral Birss
Contributors: Conrad Matthee Vicky Nel Michael Hoffmann Andrew Smith Lizanne Roxburgh
Reviewers: Matthew Child Andrew Smith

Rationale (Changed due to Same category but change in criteria)

The Riverine Rabbit is endemic to the semi-arid central Karoo region of South Africa (estimated extent of occurrence (EOO) is 54,227 km² and area of occupancy (AOO) is 2,943 km²). Recent population estimates of 157-207 mature individuals indicate an alarmingly small species population size, with no subpopulation having > 50 mature individuals. The current assessment suggests that the Riverine Rabbit should, under a precautionary purview, remain listed as Critically Endangered C2a(i) due to its inferred small population size and inferred continuing decline from habitat loss and degradation, including ongoing loss of mature individuals. There are an estimated 12 subpopulations (nine in the northern range and three recently discovered south of the historic known range) determined by clusters of >6 sightings within 10 km of each other. Large numbers of surveys throughout the distribution range have confirmed current subpopulations but failed to detect subpopulations in some areas of the historic range (indicated by museum records). Only current subpopulations are used to estimate population size. No subpopulation is estimated to exceed 50 mature individuals (range: 8-46 mature individuals). Subpopulation size was determined by summing independent sightings (non-repeat sightings) from survey data collected between 1999 and 2013. This estimate thus represents minimum sizes and it is possible that subpopulation size is higher, given that this is a cryptic species and difficult to detect. Monitoring work should be continued to improve subpopulation estimates and trends, and this species should be reassessed once further data have been generated. However, we suspect maximum subpopulation size could not be significantly higher, given that previous studies found low densities of the species on the Klipgat farm, Victoria West (0.06–0.17 individuals / ha). Subpopulations are presumably further fragmented and isolated by anthropogenic barriers to dispersal, such as impoundments in river channels and fencing, and are threatened by illegal hunting and predation by domestic animals. Total mature population size (assuming 70% adults) is estimated to be between 157 and 207 individuals. Additionally, both climate change and fracking are emerging threats to Riverine Rabbits: an initial assessment of climate change indicates that a net reduction of 89% in habitat is likely for the northern population. Fracking of the Karoo region is also likely to further reduce suitable habitat and the two threats may synergise. Thus, although population size in this analysis is likely an underestimate as it is based solely on confirmed current sightings, the Critically Endangered listing is retained (over a possible Endangered listing) as emerging threats are likely to severely threaten the already small population. Systematic monitoring and evidence for conservation interventions are desperately needed. Additionally, as the southern subpopulation may be genetically distinct from the northern animals, genetic work and subsequent taxonomic revision may require a possible reassessment of the two putative subspecies.

This species will require reassessment in the near future as recent citizen science records indicate significant increases in known EOO both southwards and eastwards. Conservation agencies are currently establishing camera traps in the areas to confirm the existence of subpopulations in these areas and once these new data are available, the assessment of this species will be updated and possibly revised.

Distribution

This species is endemic to the central Karoo region of South Africa. It is associated with the dense, discontinuous vegetation fringing the seasonal rivers. It is the only indigenous burrowing rabbit in Africa, and is dependent on soft and deep alluvial soils along the river courses for constructing stable breeding stops. Approximately 40-60% of habitat was lost or fragmented during the 1930s to 1970s due to agricultural expansion on the seasonal river flood plains across its distribution range (Robinson 1981b, Duthie et al. 1989, Duthie and Robinson 1990). Historically, this species was known to occur in five localities towards the northwestern portion of its range, along the Vis and Renoster Rivers, as well as their tributaries near Calvinia (Duthie 1989). The lack of sightings data during the last 30 years, suggests that Bunolagus monticularis is now locally extinct in these regions (Collins and Toit 2016). This is likely to be a direct consequence of the extensive agricultural expansion along riverine floodplains (Duthie et al. 1989).

A large number of surveys from 1999-2013 throughout the distribution range has improved our estimates of location and sizes of the various subpopulations, and identified a new southern population in 2004, which now consists of three known subpopulations. The southern population is distributed within three catchments: the Breede, Gouritz and Olifant River systems.

Subpopulations are defined as being made up groups of confirmed sightings along first-, second- or third-order rivers that are within a maximum of 10 km of each other. If the groups of sightings are more than 10 km from each other they are not taken as being from the same subpopulation. Due to limited information about dispersal ability of this species and the fact that known densities where home range studies were carried out showed approximately one Riverine Rabbit for every 400 m of river length, 10 km between confirmed sightings was estimated as a reasonable distance to separate subpopulations. A minimum of six sightings was taken to represent a subpopulation (potentially representing up to three breeding pairs). Where less than six sightings occurred in isolation from survey data, these were assumed to be part of the nearest subpopulation based on connectivity along the rivers.

The approximate ranges of both the northern and southern populations was calculated using Kernel Density home range estimation (buffered by 5 km) and combined to give a total extent of occurrence (EOO), estimated as 54,227 km². To calculate area of occupancy (AOO), all rivers inside the EOO were buffered by 1 km on either side. Similarly, all sightings points were buffered by a 1 km radius and were used to clip the river buffer providing a total estimate of AOO. A buffer of 1 km was chosen as most of the larger patches of riverine vegetation do not occur more than 1 km from rivers, and by buffering all rivers by 1 km, all known sightings were located within these buffered areas. AOO was thus calculated as 2,943 km². 

Population trend

Trend

Riverine Rabbits have a critically low population size. For example, Duthie et al. (1989) found low densities of the species on the Klipgat farm, Victoria West (0.06-0.17 individuals / ha). However, this sample represented too few home ranges to extrapolate to population level. Duthie et al. (1989) speculated that remaining habitat might potentially support around 1,435 individuals. However, densities may vary widely among river systems. For example, there is remaining natural habitat on the Ongers River but there is no evidence of Riverine Rabbit occupancy (Ahlmann et al. 2000). Thus the population size may be very much lower (Duthie et al. 1989).

There are an estimated 12 subpopulations, three in the southern population and nine in the northern population. Subpopulations are isolated from each other by jackal-proof fencing and severe land transformation through agricultural practices. All these subpopulations are estimated to contain less than 50 mature individuals (8–46 mature individuals, based on independent sightings in each river system). There are also an additional five possible historic subpopulations that are represented by five separate museum specimens collected in the past, but no surveys in the past 30 years have confirmed any sightings in those localities, so those five subpopulations are assumed to be locally extinct. To estimate total population size, we used survey data representing confirmed sightings along rivers to indicate size of individual subpopulations along river systems. For population size estimates, the total number of sightings across all 12 subpopulations was 380 individuals, yielding a total population estimate of 207 mature individuals (assuming 70% adults). The alternative estimate, derived from the average density of sightings per 1 km river buffer for all subpopulations multiplied by the total area (AOO), was 224 individuals in total, or 157 mature individuals (Collins and Toit 2016).

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 in a fur- and grass-lined subterranean chamber excavated in stable soils (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 (K. Collins unpubl. data).

Threats

Both populations face significant threats from ongoing habitat degradation and fragmentation due to detrimental land-use practices and new emerging habitat-transforming land uses, such as climate change and energy development (Ahlmann et al. 2000). Over the last century, ca 40-60% of the fertile alluvial floodplains and riparian habitat has been lost as a result of cultivation (for example, winter wheat production, mostly in the past) and livestock farming (ongoing) (Duthie 1989; Duthie et al. 1989, Duthie and Robinson 1990, Coetzee 1994, Ahlmann et al. 2000). Other threats to the species include hunting (hunted for sport and for bushmeat by farm workers), and accidental mortality in traps set for ‘pest’ animals on farmlands. There is also the potential that the dominance of sheep farming and emerging wildlife ranching for economically valuable species may increase the frequency of both overgrazing (and thus reduction in vital vegetation cover) and predation rates (for example, by higher Black-backed Jackal Canis mesomelas densities). Similarly, habitat degradation through fuel-wood collecting and overgrazing may have led to an increase in predation (Ahlmann et al. 2000).

There are also several emerging threats that could threaten this species. An initial assessment of climate change indicates that a net reduction of 89% in habitat is likely for the northern population (Hughes et al. 2008). Hence further study is urgently required as to potential effects of projected climate change over the entire distribution.

Fracking of the Karoo region is also a major emerging threat to Riverine Rabbit habitat due to ancillary activities associated with fracking, which could lead to increased roadkill mortalities, habitat fragmentation and altered hydrology of Karoo river systems, which in turn impacts on the species’ habitat. Similarly, wind farms are also likely to have a significant impact on the species.

Habitat quantity and quality is declining through overgrazing by livestock, resulting in reduced cover from predators and lack of sufficient forage. Reduction in streamflow owing to the construction of dams upstream has presumably also reduced habitat quality (Ahlmann et al. 2000). High livestock, and in some cases, wildlife, stocking rates have resulted in large areas of the Karoo having reduced vegetation cover and becoming dominated by unpalatable species, which have further reduced vegetation biodiversity and stocking  potential for livestock and game. Additionally, continued rural settlement expansion on the Northern Cape Province, estimated to be 9% from 2000 to 2013 (GeoTerraImage 2015), will presumably increase rates of poaching and predation by dogs. However, stewardship schemes for this species in the Karoo have also been initiated and cover 350,000 ha in the Greater Karoo. Anecdotal evidence suggests improved biodiversity and Riverine Rabbit populations on these farms, as well as greater landowner awareness of the requirements to protect Riverine Rabbits (C. Bragg unpubl. data). Continued biodiversity stewardship expansion will help to mitigate habitat loss and deterioration.

Uses and trade

The Riverine Rabbit is suspected to be opportunistically hunted for sport and for bushmeat by farm workers (Duthie and Robinson 1990, Coetzee 1994).

Conservation

 This species occurs mainly outside of formally protected areas. However, it was recently discovered (2013) on the formally protected Anysberg Nature Reserve (C. Birss unpubl. data), and there is a healthy subpopulation based in the private Sanbona Wildlife Reserve (both sites in the Western Cape Province), which is in the process of achieving formal protected status through the CapeNature biodiversity stewardship programme. There is also a substantial proportion of the species’ habitat from the northern population informally protected within the Riverine Rabbit conservancies. The primary conservation interventions involve further protected area expansion, especially through stewardship programmes, and active habitat restoration.

The Drylands Conservation Programme of the Endangered Wildlife Trust (EWT-DCP) was established in August 2003 and coordinates all conservation efforts on the Riverine Rabbit and its habitat. The programme aims to conserve the biodiversity of the Karoo region, to encourage private landowners to participate in conservation stewardship and to promote integrated land management practices that can sustain the Riverine Rabbit, its habitat and many other species while providing employment for communities and facilitating ecosystem restoration on landowners’ farms. The current projects are: 
  • Riparian habitat restoration: Initiated in 2007, the Riparian Habitat Rehabilitation Project develops and implements strategies to regenerate degraded riparian habitat in order to re-connect remaining riverine habitat fragments. Riparian zones perform a variety of functions including storing water, reducing floods, stabilizing river banks, improving water quality by trapping sediment and nutrients, and providing shelter and food for animals. They provide corridors for movement and migration of different species, including Riverine Rabbits, and act as a buffer between aquatic ecosystems and adjacent land uses. Additionally, maintaining the integrity of riparian areas will help mitigate the effects of climate change, which could potentially heavily impact this semi-arid region. To date, the programme has undertaken restoration interventions, including soil and water erosion control, re-vegetating, grazing reduction, and soil health technologies, of 350 ha of Bunolagus habitat, and is monitoring the recovery of the species in these areas, as well as the subsequent improvement of ecosystem services.
  • Establishing alternative livelihoods: Labour for the rehabilitation project is sourced locally, thereby creating employment and developing skills in poor rural communities with few other social upliftment opportunities. Through this approach a strong component of the Riparian Habitat Rehabilitation Project lies in the conservation of water resources and regional biodiversity through community involvement. The EWT-DCP established the Indigenous Karoo Plant Nursery in Loxton (Northern Cape) to support the plant needs of the Riparian Habitat Rehabilitation Project. Community members employed by the nursery are trained to propagate indigenous plants needed for the re-vegetation of Riverine Rabbit habitat within riparian zones in the Karoo. Seed is produced on the production plot within the nursery grounds and are supplemented with seeds harvested in the veld by community members.
  • Expanding Riverine Rabbit conservancies and stewardship: Little of the Riverine Rabbit’s remaining habitat is protected within nature reserve or national parks; the survival of the Riverine Rabbit is in the hands of private landowners, consisting mostly of farmers. Therefore the EWT‐DCP works in partnership with provincial conservation departments to involve private landowners in biodiversity conservation through the process of ‘stewardship’. Stewardship refers to the wise use, management and protection of that which has been entrusted to the landowner. Within the context of conservation, stewardship means protecting important ecosystems by effectively managing aspects such as invasive alien species, fires, and grazing and cultivation practices. The EWT-DCP works closely with the four Riverine Rabbit conservancies, encompassing an area of approximately 350,000 ha in the Northern and Western Cape provinces. The long‐term goal of the EWT‐DCP is to use these existing conservancies as a stepping stone to upgrade and declare specific and key properties as Protected Areas in terms of South Africa’s National Environmental Management: Protected Areas Act (No. 57 of 2003). A critical component of the work is to promote and encourage sustainable land-use practices amongst landowners and land managers in the Karoo through developing partnerships with the relevant stakeholders. Thus the EWT-DCP strives to mainstream sustainable land management principles into agricultural practices in the Karoo and into decisions made by policymakers.
  • Environmental Education and Awareness: The EWT-DCP creates awareness about Riverine Rabbit conservation efforts with farmers, farm workers and their families, school learners, teachers, and the general public. It aims to establish custodianship by cultivating a sense of ownership for the Riverine Rabbit, its habitat and the river ecosystems of the Karoo. 
Recommendations for land managers and practitioners:
  • Further surveys are needed to identify Riverine Rabbit habitat and occupancy. Hughes et al. (2008) developed a habitat model that showed potential suitable habitat east of Victoria West that might contain isolated subpopulations or offer re-introduction opportunities. The results of such surveys should feed into conservation planning. For example, the work of the Drylands Conservation Programme has succeeded in mitigating impacts of high-risk wind farms through dedicated interventions, particularly in regards to stopping development within suitable habitat. These data would also be used to develop a broad habitat map of the entire distribution range.
  • Develop public recognition schemes to encourage private landowners to form conservancies and protect the Riverine Rabbit. Presence on private land should lead to the the exclusion of ranching activities in key habitat areas. This should include developing riparian grazing guidelines to inform sustainable management of riparian areas, and a user-friendly manual of cost-effective sustainable land management technologies to encourage farmers to adopt restoration and sustainable farming practices. Finally, incentives should be identified to encourage landowners to adopt such practices that benefit the species (sensu Pasquini et al. 2010).
  • Develop a Riverine Rabbit monitoring tool to facilitate improved conservation outcomes, such as monitoring the impacts of conservation interventions (for example, restoration) on the density of subpopulations and prioritising resources to subpopulations that are declining.
  • Development of a legal tool to address Riverine Rabbit conservation: a Biodiversity Management Plan for the species in terms of the National Environmental Management: Biodiversity Act (No. 10 of 2004). This includes investigating the genetic and ecological differences between the southern and northern populations and the development of separate conservation strategies for both.
  • Although captive breeding was recommended by Collins et al. (2004), captive breeding trials in the 1990s were largely unsuccessful (Dippenaar and Ferguson 1994, Ahlmann et al. 2000). Thus, the current conservation strategy for the species does not include captive breeding as an option due to the difficulty of breeding this sensitive species in captivity and the higher chance of improving populations in the wild through concerted conservation interventions such as stewardship and habitat restoration. 
Encouraged citizen actions: 
  • Landowners can create or join conservancies to protect this species and its habitat.
  • Landowners can lower stocking levels to improve riparian ecosystem grazing systems; reduce the number of dogs on farms; and restore riparian habitats through Working for Water and/or the EWT-DCP.
  • Landowners and the public can report sightings of individuals on virtual museum platforms (for example, iSpot and MammalMAP) or provincial conservation authorities to enhance the distribution map. For example, new sightings recorded by the public and landowners are recorded in the CapeNature database. 

References 

[@book{275,
 address = {Cambridge},
 author = {Skinner, J.D. and Chimimba, C.T.},
 publisher = {Cambridge University Press, United Kingdom},
 title = {The Mammals of the Southern African Subregion},
 year = {2005}
}
,@book{570,
 address = {Parkview, South Africa},
 author = {Friedmann, Y. and Daly, B.},
 publisher = {Conservation Breeding Specialist Group (SSC/IUCN) and Endangered Wildlife Trust},
 title = {Red Data Book of the Mammals of South Africa: A Conservation Assessment},
 year = {2004}
}
,@article{3326,
 author = {Coetzee, K.},
 title = {The Riverine Rabbit (<i>Bunolagus monticularis</i>) and its habitat:  Conservation implications of an unnaturally fragmented distribution},
 year = {1994}
}
,@inbook{3326,
 address = {Gland, Switzerland},
 author = {},
 booktitle = {The African rabbits},
 editor = {Duthie, A.G. and Robinson, T. J.},
 pages = {121--127},
 publisher = {IUCN},
 title = {Rabbits, Hares and Pikas: Status Survey and Conservation Action Plan},
 year = {1990}
}
,@phdthesis{3326,
 author = {Duthie, A.G.},
 school = {University of Pretoria},
 title = {The ecology of the riverine rabbit (<i>Bunolagus monticularis</i>)},
 year = {1989}
}
,@article{3326,
 author = {Duthie, A.G., Skinner, J.D. and Robinson, T.J.},
 journal = {Biological Conservation},
 pages = {195--202},
 title = {The distribution and status of the Riverine Rabbit, <i>Bunolagus monticularis</i>, South Africa},
 volume = {47},
 year = {1989}
}
,@electronic{3326,
 address = {www.redlist.org},
 author = {Collins, K., Ahlmann, V., Matthee, C., Taylor, P.J., Keith, M. and van Jaarsveld, A.},
 title = {<i>Bunolagus monticularis</i>},
 year = {2003}
}
,@book{3326,
 address = {Pretoria},
 author = {Mucina, L. and Rutherford, M.C.},
 publisher = {Strelitzia 19. South African National Biodiversity Institue},
 title = {The vegetation of South Africa, Lesotho and Swaziland},
 year = {2006}
}
,@book{3326,
 address = {Hatfield},
 author = {Vlok, J. and Schutte-Vlok, A.-L.},
 publisher = {Umdaus Press},
 title = {Plants of the Klein Karoo},
 year = {2010}
}
,@techreport{3326,
 address = {Pretoria},
 author = {GeoTerraImage},
 title = {Quantifying settlement and built-up land use change in South Africa},
 year = {2015}
}
,@techreport{3326,
 address = {Apple Valley, MN},
 author = {Ahlmann, V., Collins, K. and Seal, U.S. },
 institution = {Conservation breeding specialist group (SSC/IUCN)},
 title = {Riverine Rabbit (<i>Bunolagus monticularis</i>): A population and habitat viability assessment workshop.},
 year = {2000}
}
,@article{3326,
 author = {Collins, K. and Toit, J.T.},
 journal = {African Journal of Ecology },
 pages = {195–206},
 title = {Population status and distribution modelling of the critically endangered riverine rabbit (<i>Bunolagus monticularis</i>)},
 volume = {54},
 year = {2016}
}
,@article{3326,
 author = {Dippenaar, S.M. and Ferguson, J.W.H.},
 journal = {South African Journal of Science},
 pages = {381–385},
 title = {Towards a captive-breeding programme for the riverine rabbit <i>Bunolagus monticularis</i>},
 volume = {90},
 year = {1994}
}
,@article{3326,
 author = {Hughes, G.O., Thuiller, W., Midgley, G.F. and Collins, K.},
 journal = {Biological Conservation},
 pages = {23–34},
 title = {Environmental change hastens the demise of the critically endangered riverine rabbit (<i>Bunolagus monticularis</i>)},
 volume = {141},
 year = {2008}
}
,@article{3326,
 author = {Pasquini, L., Cowling, R.M., Twyman, C. and Wainwright, J.},
 journal = {Conservation Biology},
 pages = {470–478},
 title = {Devising appropriate policies and instruments in support of private conservation areas: lessons learned from the Klein Karoo, South Africa},
 volume = {24},
 year = {2010}
}
,@phdthesis{3326,
 author = {Robinson, T.J.},
 school = {University of Pretoria},
 title = {Systematics of the South African Leporidae},
 year = {1981}
}
,@proceedings{3326,
 editor = {Robinson, T.J.},
 series = {Proceedings of the Wild Lagomorph Conference, University of Guelph, Ontario, Canada},
 title = {The bushman hare},
 year = {1981}
}
,@article{3326,
 author = {Robinson, T.J. and Dippenaar, N.J.},
 journal = {Annals of the Transvaal Museum },
 pages = {379–404},
 title = {Morphometrics of the South African Leporidae II: <i>Lepus</i> Linnaeus, 1758, and <i>Bunolagus</i> Thomas, 1929},
 volume = {34},
 year = {1987}
}
,@article{3326,
 author = {Robinson, T.J. and Skinner, J.D.},
 journal = {Journal of Mammalogy},
 pages = {678–681},
 title = {Karyology of the riverine rabbit, <i>Bunolagus monticularis</i>, and its taxonomic implications},
 volume = {64},
 year = {1983}
}
,@electronic{3326,
 address = {www.iucnredlist.org},
 author = {IUCN},
 title = {The IUCN Red List of Threatened Species. Version 2019-1},
 year = {2019}
}
,]
Send feedback about this assessment to SANBI

Lead agencies, Partners and Funders

See the partners page