Parotomys brantsii – Brants’ Whistling

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 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 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 Derek Keats reassessed once more data are generated. We recommend that more research and long-term monitoring of subpopulation trends, geographic distribution and Regional Red List status (2016) Least Concern* threat level are undertaken. National Red List status (2004) Least Concern Regional population effects: The bulk of the population Reasons for change No change exists in South Africa, so extra-regional rescue effect is minimal. It is a rapid disperser over short distances Global Red List status (2016) Least Concern (< 1 km), especially into areas that were recently TOPS listing (NEMBA) (2007) None overgrazed. Long distance dispersal ability is unknown, and would be dependent on corridors of suitable habitat. None CITES listing The successful colonisation of poorly vegetated mine Endemic Near dumps (Desmet & Cowling 1999) suggests an ability to establish in harsh habitats provided deep soils are *Watch-list Threat available. Evidence suggests that this species may facilitate the rehabilitation of mine dumps through the creation of nutrient-rich patches around its Distribution burrows (Desmet & Cowling 1999). 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 brantsii (A. Smith 1834) the more arid parts of the Nama-Karoo and Succulent ANIMALIA - CHORDATA - MAMMALIA - RODENTIA - Karoo biomes (Skinner & Chimimba 2005). It occurs from - Parotomys - brantsii sea level up to 1,000 m asl and generally inhabits regions with an annual rainfall of 300–500 mm. Common names: Brants’ Whistling Rat (English), Brants se Fluitrot (Afrikaans) The species distribution marginally abuts the North West Province, and it has been tentatively mentioned in Taxonomic status: Species provincial documents, but during a recent Taxonomic notes: Molecular data suggest that Parotomys survey, Power (2014) found no evidence of their existence should be synonymised with (Taylor et al. 2011, in the province. Similarly, there are no recent records from 2014), but the genera are recognised as distinct pending a the Free State except for a handful of historical records final phylogenetic analysis of species relationships within from the southwestern corner of the province the Otomyinae (Monadjem et al. 2015). This species is (N.L. Avenant pers. comm. 2014). Historically, it was also similar to P. littledalei, but distinguishable, both by its recorded 15 km west of Steytlerville, Eastern Cape dental morphology (grooved upper incisors) and by its Province, but is no longer present (G.I.H. Kerley unpubl. whistle frequency and length (Le Roux et al. 2002; data). Monadjem et al. 2015). Population Assessment Rationale It can be very common locally, as it undergoes population Listed as Least Concern because of its wide distribution irruptions in response to environmental conditions within the assessment region, its occurrence in several (Jackson 2013), and has a patchy distribution, linked to protected areas (including Kgalagadi Transfrontier Park, the distribution of deep sandy soils. This reflects its

Recommended citation: Schradin C, Malan G, Kerley GIH, Child MF. 2016. A conservation assessment of Parotomys brantsii. In Child MF, Roxburgh L, Do Linh San E, Raimondo D, Davies-Mostert HT, editors. The Red List of of South Africa, Swaziland and Lesotho. South African National Biodiversity Institute and Endangered Wildlife Trust, South Africa. The Red List of Mammals of South Africa, Lesotho and Swaziland Parotomys brantsii | 1

Figure 1. Distribution records for Brants’ Whistling Rat (Parotomys brantsii) within the assessment region

Table 1. Countries of occurrence within southern Africa (G. Malan unpubl. data). In the central Little Karoo (study site 108 km2 in size), low densities were categorised by Country Presence Origin isolated pockets of active warrens, and moderate Botswana Extant Native densities had evenly spread across the study area (G. Malan unpubl. data). At high densities, the whistling Lesotho Absent - were so abundant that they even burrowed in road Mozambique Absent - verges and open disturbed areas (and commonly ran Namibia Extant Native across roads), and their piercing whistles reverberated through the veld (G. Malan unpubl. data). In high-density South Africa Extant Native years, in Karroid Broken Veld, the density was estimated Swaziland Absent - at 128 active warrens / km2 (range 76–212 warrens / km2) (Malan 2001). In the neighbouring and more open Zimbabwe Absent - 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 requirements for burrowing as the Brants’ Whistling Rat is density decreased to 40 active warrens / km2 (standard an obligate burrower and uses burrows to avoid deviation = 28 warrens) (recalculated from Malan 2004). physiological extremes and predators (du Plessis & Kerley Jackson (2013) reports densities exceeding 50 1991). Thus, detecting a population trend is difficult, and individuals / ha in favourable conditions. At one adult per long-term, systematic monitoring is necessary. warren, the biomass estimate was 16 kg / km2 (Malan Population data from Goegap Nature Reserve, Northern 2001). Cape Province, indicate that this species is generally more Current population trend: Stable resilient and stable than P. littledalei, with densities of 2–10 individuals / ha remaining stable and consistent between Continuing decline in mature individuals: No 2001 and 2014 (C. Schradin unpubl. data). This compares Number of mature individuals in population: Unknown to a density of 15 individuals / ha being recorded for P. littledalei at the same site in 2001, and subsequently, Number of mature individuals in largest subpopulation: not having been recorded until 2014, at a density of one Unknown individual / ha (C. Schradin unpubl. data). Similarly, in the Number of subpopulations: Unknown 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 Severely fragmented: No thereafter fluctuated between moderate and low densities

Parotomys brantsii | 2 The Red List of Mammals of South Africa, Lesotho and Swaziland

of mine dumps. This should be interpreted with some Habitats and Ecology caution as the rats require forage and would only Brants’ Whistling Rat is a largely crepuscular species recolonise areas where there is at least some plant cover. (Jackson 1998), with additional short bouts of activity It is a key prey species for Pale Chanting Goshawks during the night and day (du Plessis 1989). It has a patchy (Melierax canorus) and Booted Eagles (Aquila pennatus) habitat distribution (reflecting forage availability and the in the Little Karoo, where the reproductive fitness of the need for deep soils). It is restricted to areas with latter is associated with the Karoo Broken Veld vegetation consolidated sands in semi-desert landscapes, with a low type that contains the tall shrubs and heuweltjies percentage plant cover (plant cover = 34–40%) (du necessary for high Otomyine density (Malan 2001). Pale Plessis & Kerley 1991; Malan 2001). These open areas Chanting Goshawks catch P. brantsii individuals in probably provide it with a clear view of approaching aerial proportion to the warren densities, as the birds may find it and terrestrial predators. In the Kalahari, it occurs in dune easier to catch P. brantsii on or near their warrens that are swales associated with Driedoring (Rhigozum normally devoid of any vegetation (Malan 2001). At high trichotomum) (Jackson 2013). It is not associated with rodent densities, Jackal Buzzard (Buteo rufofuscus), Black grass patches in Goegap Nature Reserve (C. Schradin Harrier (Circus maurus) and Lanner Falcon (Falco unpubl. data). It can also occur in rangelands or old fields. biarmicus) move into the area to hunt P. brantsii (Malan It feeds on a variety of annuals in spring, and mostly 2000). found in warrens include the Cape Cobra perennial succulents, grasses and shrubs in summer and (Naja nivea) and Mole (Pseudaspis cana) (G. Malan winter (Jackson 1998, 2001). Perennial succulents may pers. obs. 2014). function as key resource areas for this species and it is thus potentially sensitive to destruction of these areas. It is a central place forager; smaller food items are eaten in situ Use and Trade whilst larger items are eaten at burrow entrances or stored This species is not known to be traded or utilised in any underground (Jackson 2001). form. It lives in small colonies in extensive tunnel systems or warrens in sandy soils (De Graaff 1981; du Plessis et al. Threats 1991), especially in the relatively stone-less soil of Mima- like mounds or heuweltjies (Lovegrove & Siegfried 1986; There are no major identified threats to this species. It is Cox et al. 1987). It relies on the cooler temperatures of sometimes considered to be a pest in agricultural areas burrows to escape high temperatures (du Plessis & Kerley during population irruptions, but this is not expected to 1991; Jackson et al. 2002). Heuweltjies are earth mounds, impact the population significantly. However, this is a 25–32 m in diameter and 1.25–2.25 m in height, and are species that should be flagged as being potentially dispersed in a uniform fashion 41–51 m apart (measured threatened due to projected aridification from climate centre to centre) (Cox et al. 1987; Lovegrove & Siegfried change (Boko et al. 2007), which may affect the forage 1989). The highest heuweltjie density recorded in its resources on which this species depends through Western Cape distribution range was in the eastern Little increased frequency and duration of drought conditions. Karoo at 500 mounds / km (Lovegrove & Siegfried 1989). This impact of global climate change may be exacerbated Densities of heuweltjies accounted for 56% of the variation by the sensitivity of this rodent to high ambient in the density of P. brantsii warrens (Malan 2001). In the temperatures (Du Plessis et al. 1989), which may limit shallow soils (< 40 cm) of the central Little Karoo, it is an foraging behaviour under hotter conditions. For example, obligatory burrower that prefers deeper soils (77 cm) (du it became locally extinct in Goegap Nature Reserve after a Plessis & Kerley 1991). In this area, 58% of heuweltjies severe drought in 2003. It returned in low numbers seven surveyed contained active warrens (N = 524), whereas years later, and the population has since fully recovered 97% of warrens not on heuweltjies were inactive (N = 145) (C. Schradin unpubl. data). Thus, this species might be (Malan 2001). The relationship between heuweltjie and vulnerable to an increase in intensity of droughts. P. brantsii densities can therefore be explained by the However, it is suspected to be less threatened by dependence of P. brantsii on the suitable heuweltjie soils. droughts than the closely related Littledale’s Whistling Rat. It has a range of aerial and terrestrial predators and uses Similarly, overgrazing in some areas reduces habitat an “urgency-based” alarm call to alert conspecifics of quality for this species. Whereas grazing should be predators depending on the immediate threat (Jackson encouraged to decrease the bush encroachment (see 2001). Habitats and Ecology), overgrazing should be avoided, especially in the more open vegetation types, to limit Ecosystem and cultural services: Desmet and Cowling direct competition between farm animals and P. brantsii (1999) suggested that the nutrient-rich soil patches (Malan & Crowe 1996). As such, the proliferation of wildlife around P. brantsii burrows may facilitate the re-vegetation ranching should be monitored for its potential negative

Table 2. Threats to the Brants’ Whistling Rat (Parotomys brantsii) ranked in order of severity with corresponding evidence (based on IUCN threat categories, with regional context)

Rank Threat description Evidence in the Data quality Scale of Current trend

1 11.2 Droughts: population decline from loss of du Plessis et al. 1989 Indirect Local Increasing foraging resources. Current stress 1.2 Ecosystem Degradation.

2 2.3.2 Livestock Farming & Ranching. Current stress Masubelele et al. 2014 Indirect Regional Possibly 1.2 Ecosystem Degradation: from overgrazing. decreasing

The Red List of Mammals of South Africa, Lesotho and Swaziland Parotomys brantsii | 3

Table 3. Conservation interventions for the Brants’ Whistling Rat (Parotomys brantsii) ranked in order of effectiveness with corresponding evidence (based on IUCN action categories, with regional context)

Evidence in Data Scale of Demonstrated Rank Intervention description the scientific Current conservation projects quality evidence impact literature 1 1.1 Site/Area Protection: protected - Anecdotal - - Department of Environment and area expansion to mitigate effects Nature Conservation protected of climate change. area expansion strategy.

impacts as overgrazing may impact key vegetation types that the species requires. More research is required to Data Sources and Quality understand the net effects of local overgrazing on this species. For example, a recent study found that, contrary Table 4. Information and interpretation qualifiers for the Brants’ Whistling Rat (Parotomys brantsii) assessment to prediction, grass cover has increased and dwarf shrub cover has decreased in the Nama and Succulent Karoo, Data sources Field study (literature, unpublished), which is attributed to a general decrease in stocking rate museum records in the area (Masubelele et al. 2014). Data quality (max) Estimated Current habitat trend: Stable. Although the extent of Data quality (min) Inferred habitat is not expected to decline, there may have been a decrease in habitat quality due to overgrazing – especially Uncertainty resolution Best estimate of the key resource areas listed above. Human Risk tolerance Evidentiary settlements are not expected to encroach on this species’ habitat. Protected area expansion in the area should sustain strong subpopulations across the range. For example, the Goegap Nature Reserve increased in size from 150 to c. 250 km2 in 2014 by including several References neighbouring farms. The effects of climate change on this Boko M, Niang I, Nyong A, Vogel C, Githeko A, Medany M, species should be monitored. Osman-Elasha B, Tabo R, Yanda P. 2007. Africa. Pages 433–467 in Parry ML, Canziani OF, Palutikof JP, van der Linden PJ, Hanson CE, editors. Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Conservation Assessment Report of the Intergovernmental Panel on Climate It occurs commonly in protected areas across the range, Change. Cambridge University Press, Cambridge, UK. for example, Kgalagadi Transfrontier Park, Goegap Nature Cox GW, Lovegrove BG, Siegfried WR. 1987. The small stone Reserve and Tswalu Kalahari Reserve (Pienaar et al. content of mima-like mounds in the South African Cape region: 2010). No specific interventions are necessary at present. implications for mound origin. Catena 14:165–176. However, the species would benefit from continued protected area expansion to enable it to track shifting de Graaff G. 1981. The of Southern Africa. Butterworths, Durban, South Africa. habitats caused by climate change. Desmet PG, Cowling RM. 1999. Patch creation by fossorial Recommendations for land managers and rodents: a key process in the revegetation of phytotoxic arid soils. practitioners: Journal of Arid Environments 43:35–45.  Land managers should decrease stocking rates to du Plessis A. 1989. Ecophysiology of the bush Karoo rat Otomys conserve key resource areas. unisulcatus and the whistling rat Parotomys brantsii. M.Sc. Thesis. University of Port Elizabeth, Port Elizabeth, South Africa.  Long-term, systematic monitoring is needed to establish subpopulation trends and threat levels. du Plessis A, Erasmus T, Kerley GI. 1989. Thermoregulatory patterns of two sympatric rodents: Otomys unisulcatus and  During population irruptions, land managers can Parotomys brantsii. Comparative Biochemistry and Physiology install perches near the warrens for perch-hunting Part A: Physiology 94:215–220. raptors to sit on (Malan & Marais 2002). du Plessis A, Kerley GI. H, Winter PED. 1991. Dietary patterns of Research priorities: two herbivorous rodents: Otomys unisulcatus and Parotomys brantsii in the Karoo. South African Journal of Zoology 26:51–54.  Effects of overgrazing and climate change on key resource area quality and subpopulation size. du Plessis A, Kerley GIH. 1991. Refuge strategies and habitat segregation in two sympatric rodents Otomys unisulcatus and  Effect of extended drought periods on population Parotomys brantsii. Journal of Zoology 224:1–10. dynamics over a larger geographic scale. Jackson TP. 1998. The diurnal activity of Brants’ Whistling Rat  The ecological factors that drive the population (Parotomys brantsii): the effect of seasonal and physical irruptions and crashes seen in this species. conditions. Transactions of the Royal Society of South Africa 53:227–236.  The genetic implications of population fluctuations, and the subsequent re-colonisations and Jackson TP. 2001. Factors influencing the food collection abandonment of areas within its distribution range. behaviour of a central place forager: Brants’ whistling rat, Parotomys brantsii. Journal of African Zoology 255:15–23. Encouraged citizen actions: Jackson TP. 2013. Parotomys brantsii Brants’s Whistling Rat.  Report sightings on virtual museum platforms (for Pages 597–599 in Happold DCD, editor. Mammals of Africa. Volume III: Rodents, Hares and Rabbits. Bloomsbury Publishing, example, iSpot and MammalMAP). London, UK.

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Jackson TP, Roper TJ, Conradt L, Jackson MJ, Bennett NC. Skinner JD, Chimimba CT. 2005. The Mammals of the Southern 2002. Alternative refuge strategies and their relation to African Subregion. Third edition. Cambridge University Press, thermophysiology in two sympatric rodents, Parotomys brantsii Cambridge, UK. and Otomys unisulcatus. Journal of Arid Environments 51:21–34. Taylor PJ, Lavrenchenko LA, Carleton MD, Bennett NC, Le Roux A, Jackson TP, Cherry MI. 2002. Differences in alarm Oosthuizen CJ, Maree S. 2011. Specific limits and emerging vocalizations of sympatric populations of the whistling rats, diversity patterns in East African populations of laminate-toothed Parotomys brantsii and P. littledalei. Journal of Zoology 257: rats, genus Otomys (Muridae: : ): revision of the 189–194. Otomys typus complex. Zootaxa 3024:1–66. Lovegrove BG, Siegfried WR. 1986. Distribution and formation of Taylor PJ, Maree S, Cotterill FPD, Missoup AD, Nicolas V, Denys Mima-like earth mounds in the western Cape Province of South C. 2014. Peripatric speciation across a Neogene volcanic Africa. South African Journal of Science 82:432–436. archipelago: molecular and morphological evidence for a Pleistocene radiation of laminate-toothed rats (Otomys: Rodentia) Malan G. 2000. Raptors (Falconiformes) of the Calitzdorp district, across equatorial Africa. Biological Journal of the Linnean Society Little Karoo, South Africa (1988–1998). Durban Museum Novitates 113:320–344. 25:32–35. Malan G. 2001. Otomyine rodent refuge habitat: does it represent habitat quality for pale chanting-goshawk families? South African Journal of Wildlife Research 31:49–58. Malan G. 2004. The influence of prey abundance and co-breeders Assessors and Reviewers on reproductive output of cooperative breeding Pale Chanting- Carsten Schradin1, Gerard Malan2, Graham Kerley3, goshawks. Ostrich 75:44–51. Matthew F. Child4 Malan G, Crowe TM. 1996. The diet and conservation of 1University of the Witwatersrand, 2Tshwane University of monogamous and polyandrous pale chanting goshawks in the Technology, 3Nelson Mandela Metropolitan University, Little Karoo, South Africa. South African Journal of Wildlife 4Endangered Wildlife Trust Research 26:1–10. Malan G, Marais AvN. 2002. Guidelines for the design and Contributors management of artificial raptor perches and nest-tree stands on 1 2 3 forestry estates in South Africa: management paper. Southern Lizanne Roxburgh , Nico L. Avenant , Margaret Avery , 4 5 6 African Forestry Journal 2002:49–54. Rod Baxter , Duncan MacFadyen , Ara Monadjem , Guy Palmer7, Peter Taylor4, Beryl Wilson8 Masubelele ML, Hoffman MT, Bond WJ, Gambiza J. 2014. A 50 year study shows grass cover has increased in shrublands of 1Endangered Wildlife Trust, 2National Museum, Bloemfontein, semi-arid South Africa. Journal of Arid Environments 104:43–51. 3Iziko South African Museums, 4University of Venda, 5E Oppenheimer & Son, 6University of Swaziland, 7Western Cape Monadjem A, Taylor PJ, Denys C, Cotterill FPD. 2015. Rodents of Nature Conservation Board, 8McGregor Museum Sub-Saharan Africa: A Biogeographic and Taxonomic Synthesis. De Gruyter, Berlin, Germany. Pienaar C, Koen J, Badenhorst D. 2010. Evaluation of Tswalu Details of the methods used to make this assessment can Kalahari Reserve as a Protected Area. Internal Report: 59, be found in Mammal Red List 2016: Introduction and Department of Environment and Nature Conservation, Northern Methodology. Cape, South Africa. Power RJ. 2014. The Distribution and Status of Mammals in the North West Province. Department of Economic Development, Environment, Conservation & Tourism, North West Provincial Government, Mahikeng, South Africa.

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