Red List of South African Species

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Least Concern (LC)
Assessors: Carsten Schradin Gerard Malan 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 Gerard Malan Graham Kerley Matthew Child

Rationale

Listed as Least Concern because of its wide distribution within the assessment region, its occurrence in several protected areas (including Kgalagadi Transfrontier Park, Goegap Nature Reserve and Tswalu Kalahari Reserve), and because there are no major documented threats that could cause range-wide decline. They are also not exploited by humans. However, this is a species we need to flag as being potentially threatened due to projected aridification from climate change and overgrazing in some areas. This may affect the forage resources on which this species depends, and may be exacerbated by the sensitivity of this rodent to high ambient temperatures that may limit foraging behaviour under hotter conditions. Given that this species displays a patchy distribution and undergoes population irruptions, it may qualify for listing under the C criterion in the future, and will need to be reassessed once more data are generated. We recommend that more research and long-term monitoring of subpopulation trends, geographic distribution and threat level are undertaken.

Regional population effects: The bulk of the population exists in South Africa, so extra-regional rescue effect is minimal. It is a rapid disperser over short distances (< 1 km), especially into areas that were recently overgrazed. Long distance dispersal ability is unknown, and would be dependent on corridors of suitable habitat. The successful colonisation of poorly vegetated mine dumps (Desmet & Cowling 1999) suggests an ability to establish in harsh habitats provided deep soils are available.

Distribution

This species is restricted to the arid regions of southern Africa occurring in southwestern South Africa, southern Namibia and extreme southwestern Botswana (Skinner & Chimimba 2005). It is associated with open habitats and hard, sandy substrates throughout the arid Karoo and southern Kalahari regions (Monadjem et al. 2015). It prefers dry, coarse, sandy soils with adequate forage in the more arid parts of the Nama-Karoo and Succulent Karoo biomes (Skinner & Chimimba 2005). It occurs from sea level up to 1,000 m asl and generally inhabits regions with an annual rainfall of 300–500 mm.

The species distribution marginally abuts the North West Province, and it has been tentatively mentioned in provincial documents, but during a recent mammal survey, Power (2014) found no evidence of their existence in the province. Similarly, there are no recent records from the Free State except for a handful of historical records from the southwestern corner of the province (N.L. Avenant pers. comm. 2014). Historically, it was also recorded 15 km west of Steytlerville, Eastern Cape Province, but is no longer present (G.I.H. Kerley unpubl. data).

Population trend

Trend

It can be very common locally, as it undergoes population irruptions in response to environmental conditions (Jackson 2013), and has a patchy distribution, linked to the distribution of deep sandy soils. This reflects its requirements for burrowing as the Brants’ Whistling Rat is an obligate burrower and uses burrows to avoid physiological extremes and predators (du Plessis & Kerley 1991). Thus, detecting a population trend is difficult, and long-term, systematic monitoring is necessary.

Population data from Goegap Nature Reserve, Northern Cape Province, indicate that this species is generally more resilient and stable than P. littledalei, with densities of 2–10 individuals / ha remaining stable and consistent between 2001 and 2014 (C. Schradin unpubl. data). This compares to a density of 15 individuals / ha being recorded for P. littledalei at the same site in 2001, and subsequently, not having been recorded until 2014, at a density of one individual / ha (C. Schradin unpubl. data). Similarly, in the Little Karoo, (33°30'–33°37'S; 21°43'–21°52'E) over 14 years (1988–2001), their numbers peaked in 1989 and 1990, but thereafter fluctuated between moderate and low densities (G. Malan unpubl. data). In the central Little Karoo (study site 108 km2 in size), low densities were categorised by isolated pockets of active warrens, and moderate densities had animals evenly spread across the study area (G. Malan unpubl. data). At high densities, the whistling rats were so abundant that they even burrowed in road verges and open disturbed areas (and commonly ran across roads), and their piercing whistles reverberated through the veld (G. Malan unpubl. data). In high-density years, in Karroid Broken Veld, the density was estimated at 128 active warrens / km2 (range 76–212 warrens / km2) (Malan 2001). In the neighbouring and more open Succulent Karoo, the density was estimated at 192 active warrens / km2 (range 96–388) (Malan 2001). In a low-density year (1991) in Karroid Broken Veld, the estimated density decreased to 40 active warrens / km2 (standard deviation = 28 warrens) (recalculated from Malan 2004). Jackson (2013) reports densities exceeding 50 individuals / ha in favourable conditions. At one adult per warren, the biomass estimate was 16 kg / km2 (Malan 2001).

Threats

There are no major identified threats to this species. It is sometimes considered to be a pest in agricultural areas during population irruptions, but this is not expected to impact the population significantly. However, this is a species that should be flagged as being potentially threatened due to projected aridification from climate change (Boko et al. 2007), which may affect the forage resources on which this species depends through increased frequency and duration of drought conditions. This impact of global climate 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. It returned in low numbers seven years later, and the population has since fully recovered (C. Schradin unpubl. data). Thus, this species might be vulnerable to an increase in intensity of droughts. However, it is suspected to be less threatened by droughts than the closely related Littledale’s Whistling Rat.

Similarly, overgrazing in some areas reduces habitat quality for this species. Whereas grazing should be encouraged to decrease the bush encroachment (see Habitats and Ecology), overgrazing should be avoided, especially in the more open vegetation types, to limit direct competition between farm animals and P. brantsii (Malan & Crowe 1996). As such, the proliferation of wildlife ranching should be monitored for its potential negative impacts as overgrazing may impact key vegetation types that the species requires. More research is required 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 in protected areas across the range, for example, Kgalagadi Transfrontier Park, Goegap Nature Reserve and Tswalu Kalahari Reserve (Pienaar et al. 2010). No specific interventions are necessary at present. However, the species would benefit from continued protected area expansion to enable it to track shifting habitats caused by climate change.

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.
  • During population irruptions, land managers can install perches near the warrens for perch-hunting raptors to sit on (Malan & Marais 2002).
Research priorities:
  • Effects of overgrazing and climate change on key resource area quality and subpopulation size.
  • Effect of extended drought periods on population dynamics over a larger geographic scale.
  • The ecological factors that drive the population irruptions and crashes seen in this species.
  • The genetic implications of population fluctuations, and the subsequent re-colonisations and abandonment of areas within its distribution range.
Encouraged citizen actions:
  • Report sightings on virtual museum platforms (for example, iSpot and MammalMAP).

References 

[@book{275,
 address = {Cambridge},
 author = {Skinner, J.D. and Chimimba, C.T.},
 publisher = {Cambridge University Press, United Kingdom},
 title = {The Mammals of the Southern African Subregion},
 year = {2005}
}
,@techreport{5228,
 author = {Power, R.J.},
 institution = {Department of Economic Development, Environment, Conservation & Tourism, North West Provincial Government, Mahikeng},
 title = {The distribution and status of mammals in the North West Province},
 year = {2014}
}
,@book{14262,
 address = {Berlin, Germany},
 author = {Monadjem, A., Taylor, P.J., Denys, C. and Cotterill, F.P.D.},
 publisher = {De Gruyter},
 title = {Rodents of Sub-Saharan Africa: A Biogeographic and Taxonomic Synthesis. },
 year = {2015}
}
,@book{14262,
 address = {Durban, South Africa},
 author = {De Graaff, G},
 publisher = {Butterworths},
 title = {The Rodents of Southern Africa},
 year = {1981}
}
,@inbook{21693,
 address = {London},
 author = {},
 booktitle = {<i>Thallomys shortridgei</i> Shortridge’s Acacia Rat (Shortridge’s Thallomys)},
 editor = {Nel, J.A.J.},
 pages = {562–563},
 publisher = {Bloomsbury Publishing},
 title = {Mammals of Africa. Volume III: Rodents, Hares and Rabbits},
 year = {2013}
}
,@article{1676,
 author = {Masubelele ML, Hoffman MT, Bond WJ, Gambiza J},
 journal = {Journal of Arid Environments },
 pages = {43--51},
 title = {A 50 year study shows grass cover has increased in shrublands of semi-arid South Africa},
 volume = {104},
 year = {2014}
}
,@inbook{10103,
 address = {Cambridge, UK},
 author = {},
 booktitle = {Africa. Climate Change 2007: Impacts, Adaptation and Vulnerability},
 editor = {Boko M, Niang I, Nyong A, Vogel C, Githeko A, Medany M, Osman-Elasha B, Tabo R, Yanda P},
 pages = {433–467},
 publisher = {Cambridge University Press},
 title = {Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change},
 year = {2007}
}
,@article{15652,
 author = {Malan G.},
 journal = {South African Journal of Wildlife Research},
 pages = {49–58},
 title = {Otomyine rodent refuge habitat: does it represent habitat quality for pale chanting-goshawk families?},
 volume = {31},
 year = {2001}
}
,@article{16270,
 author = {Taylor, P.J., Lavrenchenko, L.A., Carleton, M.D., Verheyen, E., Bennett, N.C., Oosthuizen, C.J. and Maree, S.},
 journal = {Zootaxa},
 pages = {1--66},
 title = {Specific limits and emerging diversity patterns in East African populations of laminate-toothed rates, genus <i>Otomys</i> (Muridae: Murinae: otomyini): revision of the <i>Otomys typus</i> complex},
 volume = {3024},
 year = {2011}
}
,@phdthesis{16270,
 author = {du Plessis A, Erasmus T, Kerley GIH.},
 title = {Thermoregulatory patterns of two sympatric rodents: <i>Otomys unisulcatus</i> and <i>Parotomys brantsii</i>.},
 year = {1989}
}
,@article{16270,
 author = {du Plessis A, Kerley GIH.},
 journal = {Journal of Zoology},
 pages = {1–10},
 title = {Refuge strategies and habitat segregation in two sympatric rodents <i>Otomys unisulcatus</i> and <i>Parotomys brantsii</i>.},
 volume = {224},
 year = {1991}
}
,@article{16270,
 author = {du Plessis A, Kerley GIH, Winter PED.},
 journal = {South African Journal of Zoology},
 pages = {51–54},
 title = {Dietary patterns of two herbivorous rodents: <i>Otomys unisulcatus</i> and <i>Parotomys brantsii</i> in the Karoo},
 volume = {26},
 year = {1991}
}
,@article{16270,
 author = {Jackson TP, Roper TJ, Conradt L, Jackson MJ, Bennett NC.},
 journal = {Journal of Arid Environments},
 pages = {21–34},
 title = {Alternative refuge strategies and their relation to thermophysiology in two sympatric rodents, <i>Parotomys brantsii</i> and <i>Otomys unisulcatus</i>},
 volume = {51},
 year = {2002}
}
,@article{16270,
 author = {Cox GW, Lovegrove BG, Siegfried WR.},
 journal = {Catena},
 pages = {165–176},
 title = {The small stone content of mima-like mounds in the South African Cape region: implications for mound origin},
 volume = {14},
 year = {1987}
}
,@article{16270,
 author = {Desmet PG, Cowling RM.},
 journal = {Journal of Arid Environments},
 pages = {35–45},
 title = {Patch creation by fossorial rodents: a key process in the revegetation of phytotoxic arid soils},
 volume = {43},
 year = {1999}
}
,@phdthesis{16270,
 author = {du Plessis A.},
 school = {University of Port Elizabeth},
 title = {Ecophysiology of the bush Karoo rat <i>Otomys unisulcatus</i> and the whistling rat <i>Parotomys brantsii</i>. M.Sc. Thesis.},
 year = {1989}
}
,@article{16270,
 author = {Jackson TP.},
 journal = {Transactions of the Royal Society of South Africa},
 pages = {227–236},
 title = {The diurnal activity of Brants’ Whistling Rat (<i>Parotomys brantsii</i>): the effect of seasonal and physical conditions},
 volume = {53},
 year = {1998}
}
,@article{16270,
 author = {Jackson TP.},
 journal = {Journal of African Zoology},
 pages = {15–23},
 title = {Factors influencing the food collection behaviour of a central place forager: Brants’ whistling rat, <i>Parotomys brantsii</i>.},
 volume = {255},
 year = {2001}
}
,@article{16270,
 author = {Le Roux A, Jackson TP, Cherry MI.},
 journal = {Journal of Zoology},
 pages = {189–194},
 title = {Differences in alarm vocalizations of sympatric populations of the whistling rats, <i>Parotomys brantsii</i>and <i>P</i>. <i>littledalei<i/>.},
 volume = {257},
 year = {2002}
}
,@article{16270,
 author = {Lovegrove BG, Siegfried WR.},
 journal = {South African Journal of Science},
 pages = {432–436},
 title = {Distribution and formation of Mima-like earth mounds in the western Cape Province of South Africa},
 volume = {82},
 year = {1986}
}
,@article{16270,
 author = {Malan G.},
 journal = {Durban Museum Novitates},
 pages = {32–35},
 title = {Raptors (Falconiformes) of the Calitzdorp district, Little Karoo, South Africa (1988–1998).},
 volume = {25},
 year = {2000}
}
,@article{16270,
 author = {Malan G.},
 journal = {Ostrich},
 pages = {44–51},
 title = {The influence of prey abundance and co-breeders on reproductive output of cooperative breeding Pale Chanting-goshawks.},
 volume = {75},
 year = {2004}
}
,@article{16270,
 author = {Malan G, Crowe TM.},
 journal = {South African Journal of Wildlife Research},
 pages = {1–10},
 title = {The diet and conservation of monogamous and polyandrous pale chanting goshawks in the Little Karoo, South Africa},
 volume = {26},
 year = {1996}
}
,@article{16270,
 author = {Malan G, Marais AvN.},
 journal = {Southern African Forestry Journal},
 pages = {49–54},
 title = {Guidelines for the design and management of artificial raptor perches and nest-tree stands on forestry estates in South Africa: management paper.},
 volume = {2002},
 year = {2002}
}
,@techreport{16270,
 address = {Northern Cape, South Africa},
 author = {Pienaar C, Koen J, Badenhorst D.},
 institution = {Department of Environment and Nature Conservation},
 title = {Evaluation of Tswalu Kalahari Reserve as a Protected Area},
 year = {2010}
}
,@article{16270,
 author = {Taylor PJ, Maree S, Cotterill FPD, Missoup AD, Nicolas V, Denys C.},
 journal = {Biological Journal of the Linnean Society},
 pages = {320–344},
 title = {Peripatric speciation across a Neogene volcanic archipelago: molecular and morphological evidence for a Pleistocene radiation of laminate-toothed rats (Otomys: Rodentia) across equatorial Africa},
 volume = {113},
 year = {2014}
}
,]
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