Rationale

This endemic species is restricted to moist grasslands and shrublands and occurs in two isolated subpopulations in the Western Cape (Paarl and Cape Town areas) and eastern grasslands of the Drakensberg of Kwazulu-Natal and Mpumalanga provinces, as well as occasionally occurring in coastal forests. These two subpopulations may represent separate species and should be reassessed following taxonomic resolution. The estimated area of occupancy (AOO), based on remaining natural fynbos and grassland habitat in all occupied grid cells, is 5,293 km². However, since it relies on moist areas, effective AOO could be as low as 95 km² based on 32 m buffer of natural vegetation around remaining wetlands. There has been 32.8% decline in natural wetlands nationally from 1990– 2013/14, which is a combination of both genuine wetland loss through anthropogenic activities and the generally drier conditions currently that in 1990. There is also a continuing loss of habitat from agricultural expansion, human settlement sprawl and mining. In KwaZulu-Natal alone, there was a 1.2% loss per annum of natural habitat from 1994 and 2011, which means there has been / will be a 12% loss of habitat over a ten year time period. Climate change is also an emerging threat predicted to significantly reduce area of occupancy in the future (P. Taylor unpubl. data), and may synergise negatively with ongoing land-use change. Additionally, the species is naturally rare and population size may well be below 10,000 mature individuals based on its current patchy distribution and specialised habitat requirements. However, density estimates are needed to confirm population size and further vetting of museum records is required to delimit its distribution more accurately. Thus, under a precautionary purview, the species is listed as Near Threatened B2ab(i,ii,iii,iv); C2a(i) based on restricted range, fragmented habitat patches, presumed small population size and ongoing and projected declines in habitat. Although the AOO is likely an underestimate, the true occupancy is not likely to be significantly over 2,000 km². This species should be reassessed as more specific data are available, as it may qualify for a threatened category. 

Distribution

Endemic to South African with a patchy distribution in the Western Cape (Paarl and Cape Town areas) and Eastern Cape, as well as the eastern foothills of the central and northern Drakensberg in KwaZulu-Natal and Mpumalanga provinces (Monadjem et al. 2015). It occurs in the Afromontane-Afroalpine, Highveld and occasionally in the Coastal Forest Mosaic biotic zones (Taylor 2013). Otomys species are generally associated with mesic grasslands and moorlands within alpine, montane and sub-montane regions of Southern, Central, East and West Africa (Monadjem et al. 2015). This species occurs on mid-level grasslands from sea level up to at least 2,000 m asl. It has been referred to in various publications as being recorded from Eswatini but the records for this country have no specimen basis (A. Monadjem pers. comm. 2015). Barn Owl (Tyto alba) pellet analysis reveals a potentially wider distribution in the Western Cape Province than previously recorded (Avery et al. 2005). However, further vetting of museum specimens is needed to delimit distribution more accurately.

Habitat View more ecological information

Population trend

Trend

Threats

There are three main threats that may cause significant population decline in the near future:

1. Grassland and wetland habitat loss from agricultural expansion, human settlement sprawl and mining. Wetlands are the most threatened ecosystem in South Africa (Driver et al. 2012). The South African National Land-Cover change report found a 32.8% decline in natural wetlands nationally from 1990– 2013/14, which is a combination of both genuine wetland loss through anthropogenic activities and the generally drier conditions currently that in 1990 (GeoTerraImage 2015). In the Western Cape specifically, 31% of all wetlands (plus a 32 m buffer) and riparian areas have been transformed or lost to agricultural land use (Pence 2012). Habitat loss due to land transformation in the surrounding matrix further isolates wetlands from one another and exacerbates the degradation of individual wetlands. For example, sugarcane and forestry plantations are often planted right up to wetlands edges, not respecting the appropriate buffer. In KwaZulu-Natal alone, there an average loss of natural habitat of 1.2% per annum between in 1994 and 2011 from agriculture, plantations, built environments and settlements, mines and dams (Jewitt et al. 2015). Although no specific rates of habitat loss are available, 61% of Mpumalanga’s land surface between 2000 and 2014 have come under pressure from prospecting applications (Lötter 2015). In Mpumalanga, only 51% of the grasslands are still natural and not previously ploughed and 40% of the grassland vegetation types are listed as threatened (Lötter et al. 2014). Water abstraction or filling in of wetlands from human settlement and industrial expansion also leads to habitat loss. Similarly, suppression of natural ecosystem processes, such as fire, can also lead to habitat degradation through bush encroachment or loss of plant diversity through alien invasive species, and is suspected to be increasing with human settlement expansion. Overall, 45% of our remaining wetland area exists in a heavily modified condition, due primarily to onsite modification from crop cultivation, coal mining, urban development, dam construction, and overgrazing (and thus erosion) and off-site modifications from disruptions to flow regime and deterioration of water quality (Driver et al. 2012).
2. Overgrazing the vegetation around wetlands reduces ground cover and thus leads to decreased small mammal diversity and abundance (Bowland and Perrin 1989, 1993).The expansion of wildlife ranching will have to be monitored in this regard, as game overstocking may also affect wetland condition.
3. Climate change is projected to reduce area of occupancy significantly by reducing temperate grasslands and fynbos habitats. For example, climate models for the similarly mesic-adapted species, O. irroratus, show a decline in area of occupancy of 12–24% by 2050 (Taylor et al. 2016). Overgrazing and climate change may synergise to cause non-linear and accelerating population decline. More research is needed to validate these hypotheses.  

Conservation

This species is presumably present in several protected areas, but these remain to be documented comprehensively. Mitigating habitat loss outside of protected areas is urgently. The following interventions should be implemented:

•  Using previously cultivated areas for development instead of remaining natural areas: In Mpumalanga, for example, old lands or previously ploughed areas now left fallow make up 8.9% of the grassland biome (Lötter 2015), and these areas should be prioritised for further development. Similarly, in KwaZulu-Natal, abandoned agricultural fields on marginal lands offer an opportunity for further development instead of transforming virgin land and at least 4% of the landscape is available for this (Jewitt et al. 2015)
• Wetland conservation and restoration: land managers should maintain a vegetation buffer to reduce impacts of land-use practices (Driver et al. 2012).
• Holistic management of ranchlands: including de-stocking, rotational grazing and buffering wetland vegetation, are encouraged.

Recommendations for land managers and practitioners:

·         Land managers should decrease stocking rates to maintain vegetation around wetlands.

·         Prioritise old fields for development in systematic conservation planning.