SANBI

Rationale

This species is widely distributed within the assessment region and occurs in many protected areas, and can survive in multiple habitat types, including agricultural landscapes and gardens. Although commonly encountered, it occurs at naturally low densities. As there are no major threats identified, there is no reason to suspect a net population decline, but local declines are likely in areas that are overgrazed or where pesticides are used. Thus, the species is evaluated as Least Concern. Further surveys and research should focus on vetting existing museum records, as many have been misidentified as C. silacea and vice versa, leading to inaccuracies in the distribution map. Key interventions include protected area expansion of moist grassland habitats, as well as incentivising landowners to sustain natural vegetation around wetlands and keep livestock or wildlife at ecological carrying capacity.

Regional population effects: No significant rescue effects are possible as this species is too small to disperse over long distances, even though habitats are presumably connected across regions.

Distribution

This species has a wide distribution within the assessment region and southern Africa, occurring in Namibia (but not on the coast), north-eastern Botswana, Zimbabwe and parts of Mozambique (Skinner and Chimimba 2005). Within the assessment region, it is widespread throughout all provinces. Although previously it was not recorded as occurring in the middle and northern regions of the Northern Cape Province (Friedmann and Daly 2004), new data from Barn Owl (Tyto alba) pellets extends the distribution of the species to areas such as Benfontein Game Farm, Doornkloof Nature Reserve, Driekoppen and Wildflower Reserve (Avery and Avery 2011). In Swaziland, they are common in the highveld, middleveld and Lubombo regions (Monadjem 1998), and also occur in Lesotho around the Mahlanapeng and Sehonghong regions (Lynch 1994).

Existing museum records, for all Crocidura species, and for this species and C. silacea in particular, need to be exhaustively vetted, as C. cyanea and C. silacea are difficult to distinguish (Taylor and Contrafatto 1996) and this may have led to errors in both distribution maps. Similarly, the most recent confirmed museum record from North West Province was collected from Vaalkop in 1989 but many existing specimens may belong to this species (Power 2014).

Habitat View more ecological information

Population trend

Trend

This species is widespread but exists at naturally low density, although it can be locally abundant. It is often trap shy (Jooste and Palmer 1982). It is uncommon but regularly recorded in fynbos. In Rolfontein Nature Reserve, Northern Cape Province, of all species caught in traps, it was the only shrew species sampled but occurred at low density: 27 individuals compared to 648 Rhabdomys pumilio (Jooste and Palmer 1982). It is one of the more commonly encountered shrews in Swaziland and parts of north-eastern Kwazulu-Natal (Monadjem 1998, J. Harvey unpubl. data). It can be very common in gardens and houses due to compost heaps.

Threats

No severe threats are currently known to affect this species specifically, the main threat to shrews in general 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 (de-structures habitat) and decreases small mammal diversity and abundance (Bowland and Perrin 1989, 1993). Overgrazing is particularly threatening for this species, as it relies on medium to tall grass cover. 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. As this species does occur in agricultural landscapes, the use of pesticides is a threat as it is vulnerable to biomagnification due to its predominantly insectivorous diet. There are also clear overlaps and synergistic effects between these threats. We infer a continuing population decline based on loss of natural habitat.

Uses and trade

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

Conservation

This species is found in several protected areas across its range. For example, it is widely recorded in protected areas in KwaZulu-Natal (Taylor 1998) and Ferreira and Avenant (2003) recorded it in Tussen-die-Riviere Nature Reserve in Free State Province. Although no direct conservation interventions are necessary, protecting and restoring suitable habitat, such as moist grassland and fynbos patches, will benefit this species. Biodiversity stewardship schemes should be promoted to conserve such patches. Protecting these habitats may create dispersal corridors between patches that will enable adaptation to climate change. At the local scale, landowners and managers should be educated, encouraged and incentivised to conserve the habitats on which shrews and other 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 and Perrin 1989), or by maintaining buffer strips 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 and 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. Farmers should be encouraged to reduce their use of pesticides and use biological control instead.

Recommendations for land managers and practitioners:

Landowners and communities should be incentivised to stock livestock or wildlife at ecological carrying capacity and to maintain a buffer of natural vegetation around wetlands.
Enforce regulations on developments that potentially impact on the habitat integrity of grasslands and wetlands.

Research priorities:

Additional field surveys are needed to clarify and confirm the taxonomy and the distribution of this species, The effects of climate change on its distribution and abundance should be specifically modelled.
Museum records must be vetted to refine the distribution map.

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).
Practice indigenous gardening to sustain small mammals.

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