Overview

Suncus varilla – (Thomas, 1895)

ANIMALIA – CHORDATA – MAMMALIA – EULIPOTYPHLA – SORICIDAE – Suncus – varilla 

Common Names: Lesser Dwarf Shrew (English), Kleiner Dwergskeerbek (Afrikaans)

Synonyms: No Synonyms 

Taxonomic Note:
Meester et al. (1986) list four subspecies: S. v. varilla from East London; S. v. orangiae from southern KwaZulu-Natal, Free State, North West and Gauteng Provinces, as well as Lesotho, Zimbabwe and Mozambique; S. v. warreni from the northern Western Cape Province to Port Nolloth in the Northern Cape Province; and S. v. tulbaghensis from Eendekuil, Western Cape Province. As such, further studies may be needed to clarify the taxonomic status of populations currently across its range within the assessment region. 

Red List Status: LC – Least Concern, (IUCN version 3.1) 

Assessment Information

Assessor: Russo, I.M.¹, da Silva, J. M.² 

Reviewer: Patel, T.³, Erusan, R.⁴ & Smith, C.³ 

Institutions: ¹Cardiff University, ²South African National Biodiversity Institute, ³The Endangered Wildlife Trust, ⁴South African National Parks 

Previous Assessors: Taylor, P., Baxter, R. & Monadjem, A.,  

Previous Reviewer: Child, M.F. 

Previous Contributors: Avenant, N., Avery, M., Wilson, B., Palmer, G. & MacFadyen, D. 

Assessment Rationale 

The Lesser Dwarf Shrew is widespread within the assessment region, occurring across many habitat types, including gardens, and can be locally common. It presumably occurs in many protected areas, including Golden Gate Highlands National Park, and there is no evidence of net population decline, although ongoing habitat loss and degradation (particularly the loss of termitaria) may cause local declines or extinctions. Thus, we list this species as Least Concern. However, further field studies are needed to confirm its presence in other protected areas and to more accurately delimit its distribution. Additionally, taxonomic studies may be necessary to determine whether this species represents a species complex. Key interventions include protected area expansion of moist grassland and riverine woodland habitats, as well as providing incentives for landowners to sustain natural vegetation around wetlands and keep livestock or wildlife at ecological carrying capacity to avoid overgrazing of natural vegetation that shrew prey consumes. 

Regional population effects: Although its habitat is connected and intact through the Greater Limpopo Transfrontier Park, and thus dispersal is technically possible between South Africa, Mozambique and Zimbabwe, the poor dispersal ability of this species means there is unlikely to be a significant rescue effect between the populations in the assessment region and its neighbouring range. 

Reasons for Change 

Reason(s) for Change in Red List Category from the Previous Assessment: No Change 

Red List Index 

Red List Index: No change 

Recommended citation: Russo IM da Silva JM. 2025. A conservation assessment of Suncus varilla. In Patel T, Smith C, Roxburgh L, da Silva JM & Raimondo D, editors. The Red List of Mammals of South Africa, Eswatini and Lesotho. South African National Biodiversity Institute and Endangered Wildlife Trust, South Africa.

Regional Distribution and occurrence

Geographic Range 

Distributional records are scattered for the Lesser Dwarf Shrew and further field studies are needed to more accurately delimit its distribution within the assessment region and across southern Africa (Skinner & Chimimba 2005). The core distribution is South Africa, Lesotho and Zimbabwe, but it has also been recorded from Mozambique, Zambia, Tanzania, eastern Democratic Republic of the Congo, Malawi, and Nigeria. Within the assessment region, they occur or have been recorded from all provinces, most widely in the KwaZulu-Natal and Free State Provinces. Although a survey did not find this species in the North West Province (Power 2014), their capturability is dependent on food availability as they are primarily carnivorous, and this may not necessarily reflect population decline in the area. They have not been recorded from Eswatini (Monadjem 1998), but the Highveld grassland areas of the country may provide suitable habitat. This includes the Lesotho Highlands as healthy populations have been recorded in the Eastern Free State Sandly Grassland, Northern Drakensberg Highland Grassland and Drakensberg Montaine Shrubland.  

Elevation / Depth / Depth Zones 

Elevation Lower Limit (in metres above sea level): 1760 lowest recorded 

Elevation Upper Limit (in metres above sea level): 2060 highest recorded  

Depth Lower Limit (in metres below sea level): (Not specified) 

Depth Upper Limit (in metres below sea level): (Not specified) 

Depth Zone: (Not specified) 

Map 

Figure 1. Distribution records for Lesser Dwarf Shrew (Suncus varilla) within the assessment region (South Africa, Eswatini and Lesotho). Note that distribution data is obtained from multiple sources and records have not all been individually verified.

Biogeographic Realms 

Biogeographic Realm: Afrotropical 

Occurrence 

Countries of Occurrence 

Large Marine Ecosystems (LME) Occurrence 

Large Marine Ecosystems: (Not specified) 

FAO Area Occurrence 

FAO Marine Areas: (Not specified) 

Climate change

Climate change is considered to be the principal emerging threat to this species (Ogony 2014), both due to loss of habitat and habitat degradation from drying out of wetlands and because shrews cannot tolerate extreme temperatures for long and thus their foraging time will be reduced. Because of their high metabolism, low dispersal capacity and short life spans, climate change may reduce the amount of suitable habitat available. 

Population

This species is difficult to sample because of its small size, and more effort should be concentrated towards sampling disused termitaria. For example, Lynch (1986) found 56% of disused termitaria in his study were utilised by Lesser Dwarf Shrews. Barn Owl (Tyto alba) pellet analysis indicates they are common in the lake areas (for example, Sedgefield) of the Western Cape Province and constitute the major prey item in some areas (Avery et al. 2005). The rate of capture is also higher in warm wet weather conditions or post fires.  

Population Information 

Current population trend: Unknown  

Number of mature individuals in population: Unknown  

Number of mature individuals in largest subpopulation: Unknown  

Number of subpopulations: Unknown  

Extreme fluctuations in the number of subpopulations: (Not specified) 

Continuing decline in number of subpopulations: (Not specified) 

All individuals in one subpopulation: (Not specified) 

Quantitative Analysis 

Probability of extinction in the wild within 3 generations or 10 years, whichever is longer, maximum 100 years: (Not specified) 

Probability of extinction in the wild within 5 generations or 20 years, whichever is longer, maximum 100 years: (Not specified) 

Probability of extinction in the wild within 100 years: (Not specified) 

Population Genetics

No population genetics study has been conducted for this species, and limited molecular evidence is currently available. It has been proposed that the species may exist as a species complex.  

Because its overall habitat is thought to be intact, it is possible the species exists as a metapopulation, with subpopulations connected within the dispersal range of this species. However, should its habitat be more fragmented than currently perceived, discrete genetic subpopulations may exist. This will need to be confirmed through a more in depth molecular investigation. Given that the species may be difficult to sample in some regions, the utility of environmental DNA to help inform its distribution may prove invaluable. 

Even though the species is considered fairly common, due to the lack of abundance and density information and limited information of the species across its distribution, no inference can be made relating to the effective population size of this species. 

Habitats and ecology

It is commonly associated with disused termite mounds from the species Trinervitermes trinervoides (Lynch 1983, 1986), which it uses as a microhabitat for thermoregulation. The use of termitaria enables the species to survive under arid conditions. Thus, association with termite mounds may be particularly prevalent in open grassland habitats where there is no alternative cover. In the KwaZulu-Natal Province, it is not restricted to termitaria in grasslands and can be found in suburban gardens, coastal forest, savannah and forest margins (Taylor 1998). They are primarily carnivores, feeding on insects and worms and have been recorded in Barn Owl pellets (Skinner & Chimimba 2005). 

Ecosystem and cultural services: An important prey species. 

IUCN Habitats Classification Scheme 

Life History 

Generation Length: (Not specified) 

Age at Maturity: Female or unspecified: (Not specified) 

Age at Maturity: Male: (Not specified) 

Size at Maturity (in cms): Female: (Not specified) 

Size at Maturity (in cms): Male: (Not specified) 

Longevity: (Not specified) 

Average Reproductive Age: (Not specified) 

Maximum Size (in cms): (Not specified) 

Size at Birth (in cms): (Not specified) 

Gestation Time: (Not specified) 

Reproductive Periodicity: (Not specified) 

Average Annual Fecundity or Litter Size: (Not specified) 

Natural Mortality: (Not specified) 

Does the species lay eggs? (Not specified) 

Does the species give birth to live young: (Not specified) 

Does the species exhibit parthenogenesis: (Not specified) 

Does the species have a free-living larval stage? (Not specified) 

Does the species require water for breeding? (Not specified) 

Movement Patterns 

Movement Patterns: (Not specified) 

Congregatory: (Not specified) 

Systems 

System: Terrestrial 

General Use and Trade Information

There is no known subsistence or commercial use of this species. 

Local Livelihood: (Not specified) 

National Commercial Value: (Not specified) 

International Commercial Value: (Not specified) 

End Use: (Not specified) 

Is there harvest from captive/cultivated sources of this species? (Not specified) 

Harvest Trend Comments: (Not specified) 

Threats

The main threat to shrews is the loss or degradation of moist, productive areas such as wetlands and rank grasslands within suitable habitat. The two main drivers behind this are abstraction of surface water and draining of wetlands through industrial and residential expansion, and overgrazing of moist grasslands, which leads to the loss of ground cover and decreases small mammal diversity and abundance (Bowland & Perrin 1989, 1993). 

Suppression of natural ecosystem processes, such as fire, can also lead to habitat degradation through bush encroachment or loss of plant diversity through alien invasives, and is suspected to be increasing with human settlement expansion. There are also clear overlaps and synergistic effects between these threats. Across South Africa, 65% of wetland ecosystem types are threatened (48% of all wetland types are Critically Endangered, 12% are Endangered and 5% are Vulnerable; Driver et al. 2012). 

Current habitat trend: In KwaZulu-Natal Province alone, there was a 19.7% loss of natural habitat from 1994 to 2008, with an average loss of 1.2% per annum (Jewitt et al. 2015). If this rate of loss continues into the future, there will be an estimated 12% loss of habitat over 10 years. Additionally, between 2000 and 2013, there has been a 5.6% and 1.1% rate of urban and rural expansion in KwaZulu-Natal Province respectively (GeoTerraImage 2015). However, as long as natural vegetation is maintained around wetlands, rivers and artificial waterbodies, habitat for this species is suspected to remain stable. Additionally, the expansion of wildlife ranching may have a positive effect on this species as more termitaria are likely to be conserved on old fields or fallow lands. 

Conservation

The Lesser Dwarf Shrew has been recorded from several protected areas across its range within the assessment region; for example, De Hoop Nature Reserve, Western Cape Province (Avery et al. 2005). Although no specific intervention is required at present, the protection and restoration of wetlands and grasslands would be beneficial to all shrew species. Biodiversity stewardship schemes should be promoted if landowners possess wetlands or grasslands close to core protected areas or remaining habitat patches, and the effects on small mammal subpopulations should be monitored. Protecting such habitats may create dispersal corridors between habitat patches. At the local scale, landowners and managers should be educated, encouraged and incentivised to conserve the habitats on which shrews and small mammals depend. Retaining ground cover is the most important management tool to increase small mammal diversity and abundance. This can be achieved through lowering grazing pressure (Bowland & Perrin 1989), or by maintaining a buffer strip of natural vegetation around wetlands (Driver et al. 2012). Small mammal diversity and abundance is also higher in more complex or heterogeneous landscapes, where periodic burning is an important tool to achieve this (Bowland & Perrin 1993). Removing alien vegetation from watersheds, watercourses and wetlands is also an important intervention to improve flow and water quality, and thus habitat quality, for shrews. Education and awareness campaigns should be employed to teach landowners and local communities about the importance of conserving wetlands and moist grasslands. 

Recommendations for land managers and practitioners: 

• Landowners and communities should be incentivised to stock livestock or wildlife at ecological carrying capacity to avoid overgrazing and to maintain a buffer of natural vegetation around wetlands. 

• Protect disused termitaria to provide microhabitats for this species. 

Research priorities: 

• Additional field surveys are needed to clarify and confirm the distribution of this species. 

• Molecular research may be needed to disentangle a possible species complex. 

Encouraged citizen actions: 

• Citizens are requested to submit any shrews killed by cats or drowned in pools to a museum or a provincial conservation authority for identification, thereby enhancing our knowledge of shrew distribution (carcasses can be placed in a ziplock bag and frozen with the locality recorded). 

Bibliography

Avery, D.M., Avery, G. and Palmer, N.G. 2005. Micromammalian distribution and abundance in the Western Cape Province, South Africa, as evidenced by Barn owls Tyto alba (Scopoli). Journal of Natural History 39: 2047–2071. 

Bowland, A.E. and Perrin, M.R. 1989. The effect of overgrazing on the small mammals in Umfolozi Game Reserve. Zeitschrift für Säugetierkunde 54: 251–260. 

Bowland, J.M. and Perrin, M.E. 1993. Wetlands as reservoirs of small-mammal populations in the Natal Drakensberg. South African Journal of Wildlife Research 23: 39–43. 

Driver, A., Sink, K.J., Nel, J.N., Holness, S., Van Niekerk, L., Daniels, F., Jonas, Z., Majiedt, P.A., Harris, L. and Maze, K. 2012. National Biodiversity Assessment 2011: An assessment of South Africa’s biodiversity and ecosystems. Synthesis Report. South African National Biodiversity Institute and Department of Environmental Affairs, Pretoria, South Africa. 

GeoTerraImage. 2015. Quantifying settlement and built-up land use change in South Africa. Pretoria. 

Jewitt, D., Goodman, P.S., Erasmus, B.F.N., O’Connor, T.G. and Witkowski, E.T.F. 2015. Systematic land-cover change in KwaZulu-Natal, South Africa: Implications for biodiversity. South African Journal of Science 111: 1-9. 

Lynch CD. 1991. Population dynamics in the lesser dwarf shrew, Suncus varilla (Mammalia: Soricidae). Navorsinge van die Nasionale Museum Bloemfontein 7: 465-473. 

Lynch, C. D. 1986. The ecology of the lesser dwarf shrew, Suncus varilla, with reference to the use of termite mounds of Trinervitermes trinervoides. Navorsinge van die Nasionale Museum, Bloemfontein 5: 277-297. 

Lynch, C.D. 1983. The mammals of the Orange Free State, South Africa. Navorsinge van die Nasionale Museum Bloemfontein 18: 1-218. 

Meester, J.A.J., Rautenbach, I.L., Dippenaar, N.J. and Baker, C.M. 1986. Classification of Southern African Mammals. Monograph number 5. Transvaal Museum , Pretoria, South Africa. 

Monadjem A. 1998. The mammals of Swaziland. Conservation Trust of Swaziland and Big Games Parks, Mbabane, Swaziland. 

Ogony OL. 2014. Potential impacts of climate change on Mysorex species as a model for extinction risk of montane small mammals in South Africa. M.Sc. Thesis. University of Venda, Thoyandou, South Africa. 

Power, R.J. 2014. The distribution and status of mammals in the North West Province. Department of Economic Development, Environment, Conservation & Tourism, North West Provincial Government, Mahikeng. 

Skinner, J.D. and Chimimba, C.T. (eds). 2005. The Mammals of the Southern African Subregion. Cambridge University Press, United Kingdom, Cambridge. 

Taylor, P. 1998. The Smaller Mammals of KwaZulu-Natal. University of Natal Press, Pietermaritzburg, South Africa.