Rationale

This endemic subspecies is known from at least five locations along the coasts of  the Western and Northern Cape provinces, with an estimated area of occupancy of 80 km² (assuming a 16 km² grid cell area), partially sufficient to warrant Endangered status under criteria B2ab(iii,iv). However, it is probably more widespread than current records suggest, as the northernmost (Port Nolloth) and southernmost (St Helena Bay) localities are 630 km apart on the continuous Namaqua Coastal Plain, and this subspecies is known to occur at least 20 km inland (for example, at Compagnies Drift near Lamberts Bay). Populations are probably not severely fragmented and the extent of occurrence is likely to be > 12,000 km². Although subject to some habitat loss and disturbance at a few locations due to mining of coastal dunes for alluvial diamonds along the Northern Cape coastline (Kleinsee to Alexander Bay), the amount of available habitat remaining within the entire subspecies range is deemed to exceed the thresholds for Endangered listing under criterion B1b(iii). It is conserved in one protected area, so overall declines in area of occupancy, numbers of populations and population sizes are unlikely. However, listing of this subspecies as Vulnerable under criteria B1ab(iii) and/or B2ab(iii) is warranted given the estimates for area of occupancy and extent of occurrence above. Further field surveys are required to more accurately delimit range and occupancy.

Regional population effects: The Namibian subspecies is likely to be elevated to species status, rendering the South African subspecies as an endemic species as the Orange River poses a barrier to dispersal. Thus, no rescue effect is possible.

Distribution

Habitat View more ecological information

Population trend

Trend

Threats

Alluvial diamond mining in coastal areas in Northern Cape (Kleinsee and Port Nolloth) results in marked alteration and fragmentation of habitats at some locations due to the removal of topsoil (Smithers 1986). These threats are, however, localised. Much of the range of this subspecies coincides with coastal desert where human influence on habitats is not substantial, so the overall population is probably not in decline. Coastal tourism developments along the south-western coast of South Africa (St Helena Bay to Lambert’s Bay), and agricultural practices on the Namaqualand coastal plain (and associated inland valleys) have resulted in some habitat alteration, but threats are considered minor as this subspecies can survive in mildly transformed habitats. Although rehabilitation of mined areas may be partially mitigating habitat loss, these localised impacts, together with the few known populations and limited EOO and AOO of the subspecies, are sufficient for threatened listing.

Uses and trade

This subspecies is not known to be utilised or traded in any form.

Conservation

• Field surveys to locate additional subpopulations.
• Surveys into the population viability within rehabilitated mining areas.
• Assessment of connectivity among subpopulations.

• Ecological requirements and niche tolerances.
• Systematic surveying to accurately assess accurate distribution limits of this subspecies.
• Population genetic analysis including representatives of all known subpopulations representative of entire distribution range to identify and quantify population substructure and levels of historic and current gene flow.
• Studies assessing subpopulation trends and the severity of threats outside of protected areas.
• Research into population recoveries in rehabilitated mined areas.

• Report sightings on virtual museum platforms (for example, iSpot and MammalMAP), especially outside protected areas. 
• Deposit any dead specimens found in a state or provincial museum, together with information on the date and site where found.
• Create indigenous vegetation gardens.