Red List of South African Species

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Least Concern (LC)
Assessors: Carsten Schradin Neville Pillay Graham Kerley Matthew Child
Contributors: Lizanne Roxburgh Nico Avenant Margaret Avery Rod Baxter Duncan MacFadyen Ara Mondajem Guy Palmer Peter Taylor Beryl Wilson
Reviewers: Carsten Schradin Neville Pillay Graham Kerley Matthew Child

Rationale

Listed, under a precautionary risk tolerance, as Near Threatened B2b(iii,iv)+c(iii) as it is suspected to be more threatened by droughts than the closely related Brants’s Whistling Rat (P. brantsii) and became locally extinct in Goegap Nature Reserve after a severe drought in 2003 (retuning only in low numbers in 2014). Thus, this species might be especially vulnerable to an increase in intensity and duration of droughts as a consequence of climate change. Additionally, habitat degradation from overgrazing of rangelands may threaten this species as it is more reliant on plant cover than P. brantsii. However, it also has a wide distribution within the assessments region and occurs in several protected areas (including Richtersveld and Augrabies National Parks). Ongoing protected area expansion in the area should sustain strong subpopulations across the range. We recommend more research and long-term monitoring of subpopulation trends, geographic distribution, effects of climate change and threat level. Vulnerability to increased drought periods are of special research emphasis. This species probably qualifies for Least Concern, but further subpopulation trends and area of occupancy estimates are needed to demonstrate this. It should be reassessed following new data.

Regional population effects: Possible through dispersal from Namibia across contiguous and largely unfragmented habitat, although the Orange River represents a barrier to dispersal from Namibia. Dispersal ability might be low, as indicated by the long absence from Goegap Nature Reserve after the 2003 drought. Dispersal might depend on connected areas of shrub growth.

Distribution

This species has a narrow distribution in the driest parts of southern Africa, from the western regions of South Africa north into Namibia and mostly along a narrow strip of desert (Monadjem et al. 2015). It occurs in the South-West Africa Biotic Zone (Namib Desert and Karoo regions) (Jackson 2013), and is absent from the central Namib Desert. It has not been recorded from Angola. Museum records need vetting to improve the accuracy of its distribution map. It is suspected to have an area of occupancy of < 2,000 km2 due to its patchy distribution and vulnerability to local extinctions. However, this should be more accurately quantified in future assessments.

Population trend

Trend

Relatively common in suitable habitats (although caught seldomly in small mammal traps) and is rarely seen but frequently heard (Jackson 2013). It undergoes population irruptions in response to environmental conditions and has a patchy distribution, linked to the distribution of deep sandy soils. Thus, detecting a population trend is difficult and long-term, systematic monitoring is necessary. The presence of P. littledalei in an area is usually indicated by a complex warren system under bushes (Coetzee & Jackson 1999; Jackson 2000). Population data from Goegap Nature Reserve, Northern Cape Province, indicate that it is more prone to local extinction than P. brantsii, where a density of 15 individuals / ha was recorded in 2001 and subsequently was not recorded until 2014 at a density of 1 individual / ha (C. Schradin unpubl. data). At the same site, P. brantsii exhibited densities of 2–10 individuals / ha remaining stable and consistent between 2001 and 2014 (C. Schradin unpubl. data).

Threats

This is a species that should be flagged as being potentially threatened due to projected aridification as a result of climate change (Boko et al. 2007). Increased frequency and duration of drought conditions may affect the forage resources on which it depends. This response to global change may be exacerbated by the sensitivity of this rodent to high ambient temperatures (du Plessis et al. 1989), which may limit foraging behaviour under hotter conditions. For example, it became locally extinct in Goegap Nature Reserve after a severe drought in 2003 and returned in low numbers in 2014 (C. Schradin unpubl. data).

Similarly, overgrazing in some areas reduces habitat quality. This species may be more threatened by overgrazing than P. brantsii because it is more restricted to areas of adequate cover (Jackson 2000). Whereas grazing should be encouraged to decrease bush encroachment (see Habitats and Ecology), overgrazing should be avoided, especially in the more open vegetation types. As such, the proliferation of wildlife ranching should be monitored for its potential negative impacts as overgrazing may impact key vegetation types that this species requires. However, more research is needed to understand the net effects of local overgrazing on this species. For example, a recent study found that, contrary to prediction, grass cover has increased and dwarf shrub cover has decreased in the Nama and Succulent Karoo, which is attributed to a general decrease in stocking rate in the area (Masubelele et al. 2014).

Uses and trade

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

Conservation

It occurs commonly but patchily in protected areas across the range; for example Richtersveld and Augrabies National Parks and Goegap Nature Reserve. Systematic monitoring is required to assess population trends and dynamics. The species would benefit from continued protected area expansion to enable it to track shifting habitats caused by climate change. For example, WWF South Africa is purchasing Knersvlakte to increase the size of a reserve and, in 2014, the Goegap Nature Reserve was increased in size, from 150 km2 to around 250 km2, by including several neighbouring farms. Removing ground cover and green plant material through overgrazing will negatively affect this species and thus rangelands should be managed holistically by lowering stocking rates and conserving buffer zones.

Recommendations for land managers and practitioners:
  • Land managers should decrease stocking rates to conserve key resource areas.
  • Long-term, systematic monitoring is needed to establish subpopulation trends and threat levels.
Research priorities:
  • Effects of overgrazing and climate change on key resource area quality and distribution and its impact on subpopulation trends.
  • Effect of extended drought periods of population extinction over a larger geographic scale.
  • Long distance dispersal ability (to re-colonise habitat where the species became locally extinct), which includes assessing the extent of fragmentation of subpopulations.
Encouraged citizen actions:
  • Inform local farmers and guest farms about the concerns regarding the vulnerability of this species to droughts to get information on subpopulation trends.
  • Report sightings on virtual museum platforms (for example, iSpot and MammalMAP).

References 

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,]
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