Red List of South African Species

Alternatively, Explore species
| National Red List categories | Partners |
Least Concern (LC)
Assessors: Fabien Génin Judith Masters
Contributors: Yvette Ehlers-Smith Samantha Page-Nicholson
Reviewers: Matthew Child

Rationale

Listed as Least Concern, as the species is relatively widespread within the assessment region and in sub-Saharan Africa, and present in several protected areas in South Africa (including Kruger National Park). Northern and northeastern South Africa, however, comprise the southernmost limit of its distribution, within which the species is confined to moist savannah and riverine forest, which are naturally fragmented habitats, and Thick-tailed Bushbaby subpopulations are highly localised. Both the large size of the animals and their habit of sleeping in tree holes during the day make them favoured bushmeat in northern KwaZulu-Natal, and their presence in markets attests to their use in traditional medicine. The effect of this culling on population viability cannot be assessed from available information. The species’ range is unlikely to have expanded as a result of the conversion of land use from livestock to savannah wildlife ranching, and is likely to have contracted due to urbanisation and transformation of suitable habitat to agricultural fields. Removal of dead trees from these areas is also likely to limit available day-time resting sites and consequent protection from predators. An assessment of population size and density, and the degree of population fragmentation, is necessary to assess the status of this species. Once these data have been generated, a reassessment is recommended.

Regional population effects: The species’ range is apparently continuous through tropical and subtropical sub-Saharan Africa, but areas of suitable habitat within this range are fragmented and likely to confer a degree of genetic isolation. Dispersal is suspected to occur along the northern border of South Africa through the Greater Mapungubwe and Great Limpopo transfrontier conservation areas between Zimbabwe, the Tuli Block and Mozambique, and into northeastern KwaZulu-Natal, via riparian and dune forest corridors through the Lubombo Transfrontier Conservation Area. The South African population comprises the southerly extreme of the species’ distribution, and much of the available habitat is likely to be marginal. Nevertheless, rescue efforts are unlikely to be necessary at this stage.

Distribution

At species level, O. crassicaudatus has a “Zambezian” distribution, from Angola in the west to Kenya and Tanzania in the east, and KwaZulu-Natal Province, South Africa, in the south. Its preferred habitat is a natural mosaic of coastal or riverine forest-savannah transition, so that it is most abundant in fragmented habitat. In dry regions, Thick-tailed Bushbabies follow rivers, creating a discontinuous distribution. On the east coast it is found in coastal forest and thicket, and the population was probably continuous in the recent past, but is less so today because of incursions from urbanisation and agriculture (sugar cane and forestry plantations).

The only subspecies to occur within the assessment region is O. c. crassicaudatus. Its range extends north from the vicinity of Mokopane and Makhado into northern Limpopo Province, and eastwards through Mpumalanga and Swaziland into northern KwaZulu-Natal and southern Mozambique, occurring marginally on the Eastern Cape coast (Skinner & Chimimba 2005). In western Swaziland, it has adapted to wattle forests and is found around Mbabane (Skinner & Chimimba 2005). Otolemur c. crassicaudatus grades into and is replaced by O. c. kirkii in Zimbabwe, the Botswanan Tuli Block, southern Malawi (Chikwawa region) and central Mozambique. The pelage of this subspecies is paler than that of O. c. crassicaudatus, and the tail and extremities have a rufous brown tint. Further north, in Angola, Zambia, Malawi and northern Mozambique (predominantly in Brachystegia woodland), and into southern Democratic Republic of the Congo and southern Tanzania (Tabora), O. c. kirkii is replaced by O. c. monteiri, a silvery-grey subspecies with brown ear pinnae and extrem ities. Otolemur c. monteiri has also been reported from Rwanda, northern Tanzania and Kenya, where dark brown to black ears and extremities have led to it being given the name O. c. argentatus by some researchers.

Population trend

Trend

This is a relatively common species within a restricted part of the country. No population estimates have been made as the subpopulations are not considered to be threatened. However, the fragmented nature of its preferred habitat and the potential for genetic isolation that this confers indicate in favour of population studies to investigate local levels of genetic diversity. Dispersal ability is unknown but suspected to be greater than subspecies at low latitudes (Beaudrot et al. 2014). At present we suspect that the population is stable as the species is present in many protected areas, but this awaits confirmation.

Threats

The only potential threat is habitat destruction and fragmentation. The species occurs in several protected areas, but may be locally threatened in parts of its range through the loss of suitable forest habitat. Within the assessment region, timber plantations and human settlement have fragmented the Thick-tailed Bushbaby’s habitat, which may lead to inbreeding in isolated subpopulations. For example, in the Soutpansberg, Limpopo Province, pine and eucalyptus plantations and residential housing expansion reduced forest cover by 20% over a 16-year period between 1990 and 2006 (Munyati & Kabanda 2009). The animals are also illegally harvested for the pet trade, and traditional medicine, and are also poached for human consumption (for example, in KwaZulu-Natal Province), which may result in local declines.

Uses and trade

This species is used locally for the traditional medicine trade and also as bushmeat. Although the impacts have not been measured, it is often seen in muthi markets (for example, Whiting et al. 2011) and anecdotal evidence suggests its use in the bushmeat trade. Although the trend in offtake is unknown, this is not suspected to have a major effect on the population overall.

Conservation

Key conservation areas for the Thick-tailed Bushbaby include the Ezemvelo KZN Wildlife game reserves in KwaZulu-Natal, particularly Mkhuze, Hluhluwe-iMfolozi, Ndumo and Tembe, as well as the iSimangaliso Wetland Park complex, where Cape Vidal and St. Lucia hold strong populations. They are abundant in Kruger National Park. Their cryptic nocturnal habits make bushbabies difficult to observe for casual tourists, but in Ithala, Hluhluwe and Skukuza they often visit the rest camps. They can also be seen in the Sodwana camping ground, as they visit the Albizia trees to gather gum.

Protected area expansion and connection of forest habitats through corridors and transfrontier conservation areas, such as that being developed in Maputaland (Smith et al. 2008), are the most important interventions for this species. Protection of riparian forest passageways are particularly important. Conservationists should continue to enforce protected area rules and prevent the illegal harvesting of firewood.

Galagos adapt well and breed very successfully in captivity, and such facilities can be used to reintroduce this species into conservancies and other protected areas. However, reintroductions are not recommended at this stage.

Recommendations for land managers and practitioners:
  • Landowners should continue to form conservancies to protected critical forest habitat.
  • Reserve managers should prevent the removal of dead trees for firewood. These old trees comprise an important source of wood boring insects, as well as cavities for shelter
  • Captive breeding programmes for reintroduction would be counter-productive at this stage, as they would confuse the picture of standing genetic diversity. Our recommendations are that managers investigate the potential presence of local Otolemur subpopulations before targeting riverine forest belts for tourist accommodation or housing developments.
Research priorities: The African Primate Initiative for Ecology and Speciation (APIES) at the University of Fort Hare has an ongoing project plotting morphological, genetic and behavioural diversity of galago species throughout sub-Saharan Africa against past and present vegetation maps. The project aims to characterise the crucial habitat characteristics necessary for the survival of all extant species, and to assess which populations are most at risk of extinction.

Research has also been undertaken on the impacts of changing land-use on biodiversity, particularly on mammals. The study, based at the University of KwaZulu-Natal, and a collaboration with Ezemvelo KZN Wildlife, examined the metapopulation dynamics of forest mammals in the fragmented sub-tropical coastal forests of southern KwaZulu-Natal (June 2014 – June 2016).

Current research priorities are:
  • The taxonomy of this species has been relatively well researched. What is urgently required is a phylogeographic assessment of the degree of isolation of local subpopulations, and the potential for gene exchange among them. A measure of whether fragmentation is increasing, or affecting population sizes and heterozygosity will enable more robust projections of population impacts.
  • Thick-tailed Bushbabies’ requirement for moist riparian woodland and thicket in the interior regions of its range is likely to limit dispersal. No data exist for population size, extent of occurrence and trends. Little is known about the degree of isolation between, or level of inbreeding within, fragmented populations, and no survey has been undertaken as to the likely size of the South African population.
  • Investigating the efficacy of educating local communities to decrease poaching rates.
Encouraged citizen actions:
  • Because of the crucial need for genetic information on local Otolemur populations, tissue samples would be extremely useful. Anyone encountering a dead animal is requested to take a sample of muscle tissue or even a small piece of the ear pinna, either deep freeze it or place it in 70% alcohol, and submit it to the APIES team (website link above). Complete bodies are also invaluable for research; transport can be organised. A non-invasive technique for genetic sampling of live animals is to pull a few hairs from the body, including some follicular cells that contain DNA.
  • With respect to habitat preservation, landowners can create conservancies to protect natural forest habitat in KwaZulu-Natal, Limpopo and Mpumalanga. Albizia trees are much preferred by Otolemur crassicaudatus. Any person residing within the assessment region can assist the local wildlife by planting trees and shrubs indigenous to their area, rather than exotic species.
  • Sightings outside private lands or protected areas can be reported on virtual museum platforms (for example, iSpot and MammalMAP).

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}
}
,@techreport{3326,
 address = {Pretoria},
 author = {GeoTerraImage},
 title = {Quantifying settlement and built-up land use change in South Africa},
 year = {2015}
}
,@article{2274,
 author = {Whiting, M.J., Williams, V.L. and Hibbitts, T.J.},
 journal = {Journal of Zoology},
 pages = {84--96},
 title = {Animals traded for traditional medicine at the Faraday market in South Africa: species diversity and conservation implications},
 volume = {284},
 year = {2011}
}
,@article{4144,
 author = {Munyati, C. and Kabanda, T.A.},
 journal = {Regional Environmental Change},
 number = {1},
 pages = {41–56},
 title = {Using multitemporal Landsat TM imagery to establish land use pressure induced trends in forest and woodland cover in sections of the Soutpansberg Mountains of Venda region, Limpopo Province, South Africa},
 volume = {9},
 year = {2009}
}
,@book{4221,
 address = {Washington, DC, USA},
 author = {Groves, C.P.},
 publisher = {Smithsonian Institution Press},
 title = {Primate Taxonomy},
 year = {2001}
}
,@article{4221,
 author = {Grubb, P., Butynski, T.M., Oates, J.F., Bearder, S.K., Disotell, T.R., Groves, C.P. and Struhsaker, T.T.},
 journal = {International Journal of Primatology},
 pages = {1301–1357},
 title = {Assessment of the diversity of African primates},
 volume = {24},
 year = {2003}
}
,@book{4221,
 address = {San Diego, California, USA},
 author = {Kingdon, J.},
 publisher = {Academic Press},
 title = {The Kingdon Field Guide to African Mammals},
 year = {1997}
}
,@article{4221,
 author = {Jewitt D, Goodman P.S., Erasmus B.F.N., O’Connor T.G.; and Witkowski E.T.F.},
 journal = {South African Journal of Science },
 pages = {1–9.},
 title = {Systematic land-cover change in KwaZulu-Natal, South Africa: implications for biodiversity},
 volume = {111},
 year = {2015}
}
,@article{4221,
 author = {Smith RJ et al.},
 journal = {Biological Conservation},
 pages = {2127–2138},
 title = {Designing a transfrontier conservation landscape for the Maputaland centre of endemism using biodiversity, economic and threat data},
 volume = {141},
 year = {2008}
}
,@book{8788,
 address = {Barcelona},
 author = {Mittermeier, R.A., Rylands, A.B. and Wilson D.E.},
 publisher = {Lynx Edicions},
 title = {Handbook of the Mammals of the World: Volume 3 Primates},
 year = {2013}
}
,@article{15643,
 author = {Beaudrot L, Kamilar JM, Marshall AJ, Reed KE},
 journal = {International Journal of Primatology },
 pages = {1088–1104},
 title = {African Primate Assemblages Exhibit a Latitudinal Gradient in Dispersal Limitation.},
 volume = {35},
 year = {2014}
}
,@article{15643,
 author = {Coquerel C},
 title = { Notes de Mammalogie. 1. Genre nouveau de Lémurien. Revue et Magasin de Zoologie 2, Part XI: 457-460; 2. Renseignements sur quelques Lémuriens de Madagascar. Revue et Magasin de Zoologie 2 Part XI:4461–464.},
 year = {1859}
}
,@article{15643,
 author = {Dixson AF, van Horn RN},
 journal = {Journal of Zoology},
 pages = {517–526},
 title = {Comparative studies of morphology and reproduction in two subspecies of the greater bushbaby, <i>Galago crassicaudatus crassicaudatus</i> and G. <i>c. argentatus</i>},
 volume = {183},
 year = {1977}
}
,@book{15643,
 address = {Cambridge, UK},
 author = {Entwistle A, Dunstone N},
 publisher = {Cambridge University Press},
 title = {Priorities for the conservation of mammalian diversity: has the panda had its day?},
 year = {2000}
}
,@article{15643,
 author = {Masters JC, Lumsden WHR, Young DA},
 journal = {International Journal of Primatology},
 pages = {573–592},
 title = {Reproductive and dietary parameters in wild greater galago populations},
 volume = {9},
 year = {1988}
}
,@article{15643,
 author = {Nash, L.T., Bearder, S.K. and Olson, T.R.},
 journal = {International Journal of Primatology},
 pages = {57–80},
 title = {Synopsis of Galago species characteristics},
 volume = {10},
 year = {1989}
}
,@article{15643,
 author = {Olson TR},
 journal = {American Journal of Physical Anthropology},
 pages = {259–259},
 title = {Systematics and zoogeography of the greater galagos},
 volume = {54},
 year = {1981}
}
,]
Send feedback about this assessment to SANBI

Lead agencies, Partners and Funders

See the partners page