409.

Brants’s Whistling Rat

Parotomys brantsii

French: Otomys de Brants / German: Brants-Pfeifratte / Spanish: Rata silbadora de Brant

Taxonomy. Euryotis brantsii A. Smith, 1834,

“South Africa,—plains of the interior.” Fixed by O. Thomas and H. Schwann in 1904 as “Klipfontein,” Mpumalanga Province, South Africa.

Parotomys brantsii is similar in external appearance to P. lttledaler but differs in dental characteristics (grooved upper incisors inP. brantsi, ungrooved in P. littledalei) and frequency of their alarm calls (10 kHz in P. brantsii, 7-7 kHz in P. littledaler). Monotypic.

Distribution. S & SE Namibia, extreme SW Botswana, and W South Africa (Northern and Western Cape provinces).

Descriptive notes. Head—body 141-158 mm, tail 93-115 mm, ear 15-22 mm, hindfoot 28-33 mm; weight 75-111 g. Brants’s Whistling Rat is medium to large in size and robust, with large blunt head,shorttail, and shaggy fur. Fur is soft, dense, and siennayellow speckled with blackish brown above, slightly paler on flanks, and grayish white below. Head has grayish white and blunt muzzle, with russet forehead and nasal region. Ears are large, rounded, and dark, with short brown or pale hair. Limbs are short, and digits are long with long slender claws; forefeet have four digits (first digit highly reduced), and hindfeet have five digits. Tail is short (c.63% of head-body length), dark brown above and reddish orange on sides and below. Females have four pairs of nipples. Upper incisors have one deep and one shallow groove, and lower incisors lack grooves. M, has four laminae, and M’ has two laminae. Chromosomal complementis 2n = 44 and FN = 79-80.

Habitat. Open arid areas and hard sandy substrates. In the Kalahari, Brants’s Whisthing Rats are associated with the shrub Rhigozum trichotomum ( Bignoniaceae) on dune slopes and banks of dryriver beds.

Food and Feeding. Brants’s Whistling Rat eats a wide variety of plants including shrubs, annuals, geophytes, grasses, and succulents. Foraging occurs close to burrows. Small pieces of fresh plants are nipped off and eaten immediately, and larger fresh plant parts are carried back to food stores in burrows.

Breeding. Breeding system is based on “scramble competition polygyny,” whereby males actively solicit females from nearby burrows. Timing of reproduction is opportunistic and depends on rainfall. In areas with winter rainfall, there is a winter—spring (May-October) peak in number of reproductively active females. Gestation is 38 days. Litters have 3-4 young in Namaqualand, and embryo numbers were 1-3 in Botswana. During lactation, females spend more than 50% of the day underground in burrows. Young nipple-cling until 14 days of age.

Activity patterns. Brants’s Whistling Rat is diurnal and terrestrial, occasionally scansorial, climbing shrubs to forage. Foraging activity is typically concentrated in early morning and late afternoon but may occur throughout the day. Short nocturnal feedings bouts have been recorded on moonlit nights.

Movements, Home range and Social organization. Brants’s Whistling Rats construct large and complex burrows. In Namaqualand, burrows had 1-6 nest chambers, covered an average of 72-9 m?, and hadan average of 92 entrances. Individuals change nest chambers every 1-6 days, possibly to minimize ectoparasite loads. Burrows are situated close to one another,typically occupied by solitary individuals and separated by surface runways, allowing interaction among individuals. Inter-male aggression is low, but females are aggressive toward intruding males. Mostjuveniles are philopatric, dispersing less than 20 m from their natal burrows. At high densities, foraging and burrowing activities can disturb vegetation leading to changes in floral composition, but at lower densities, burrows can facilitate rehabilitation ofsoils following mining. Alarm calls are used to signal predators: longer duration calls indicating lowerrisk (e.g. slow-moving snake) and shorter duration calls indicating more urgent short-term risk (e.g. fast-flying raptor).

Status and Conservation. Classified as Least Concern on The IUCN Red List.

Bibliography. Happold (2013a), Jackson (1998a, 1998b, 1999, 2000b, 2001), Jackson et al. (2002), Meester (1988), Monadjem et al. (2015), Nel & Rautenbach (1974), du Plessis et al. (1991), Rambau et al. (1997), Roper et al. (2002), le Roux et al. (2002), Thomas & Schwann (1904).