Rhizomys pruinosus Blyth 1851
Creators: name: Don E. Wilson
name: Russell A. Mittermeier
name: Thomas E. Lacher, Jr
Publisher: name: Lynx Edicions
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Mammalia
Rodentia
Spalacidae
Rhizomys
Rhizomys pruinosus

description: 13.
Hoary Bamboo Rat
Rhizomys pruinosus
French: Rhizomys grisonnant / German: Graue Bambusratte / Spanish: Rata de bambu canosa
Taxonomy. Rhizomys pruinosus Blyth, 1851,
Cherrapunji, Khasi Hills, India.
Classically treated as a member of the subgenus Rhizomys. Distributions of subspecies are poorly delineated, and multiple species may be present. Five subspecies recognized.
Subspecies and Distribution.
R.p.pruinosusBlyth,1851—Meghalaya,SAssam,extremeNEArunachalPradesh,Nagaland,Manipur,NTripura,andNMizoram(NEIndia),NWMyanmar,andWYunnan(SWChina).
R.p.latoucheiThomas,1915—SEChinaSoftheYangtzeRiver,includingGuizhou,Hunan,Jiangxi,Fujian,Guangxi,andGuangdong.
R.p.pannosusThomas,1915—EMyanmar,Thailand,Laos,SCambodia,andVietnam.
R.p.senexThomas,1915—NEMyanmarandSYunnan(SWChina).
R. p. umbriceps Thomas, 1916 — N Malay Peninsula S to Perak (N Malaysia). Also present in NW India (Himachal Pradesh), but subspecies involved not known.
Descriptive notes. Head-body 240-350 mm, tail 90-130 mm; weight 1.5-2.5 kg. The Hoary Bamboo Rat is grayish brown to chocolate-brown, with lighter venter. Intermittent long white-tipped guard hairs give grizzled appearance. Pelage is dense and soft. White-tipped hairs and dense pelage are less pronounced in the southern part of its distribution. Almost hairless tail is longer relative to head-body length than on the Chinese Bamboo Rat (R. sinensis). Upper incisors are extrabuccal, orange, and slightly proodont; molars are orange. Rostrum is narrower than in the Chinese Bamboo Rat, and sagittal crest is lyre-shaped. There are 8-10 nipples: 1 or 2 pairs of pectoral + 3 pairs of inguinal. Minute, presumably non-functional, pair of pectoral nipples is present on some individuals. Diploid numberis 2n = 50.
Habitat. Bamboo thickets, bamboo hillsides and montane forest, tropical and subtropical deciduous forests, grassland mixed with secondary forest, shrub forest, and, with less frequency, pine and fir forests. The Hoary Bamboo Ratis not common in agricultural areas or mature forest. In the northern parts of its distribution, it is found in bamboo thickets or beardgrass (Polypogon, Poaceae) at elevations of less than 1000 m in China and less than 1500 m in north-eastern India, especially where it overlaps with the Chinese Bamboo Rat, which lives at higher elevations. In the southern part ofits distribution, the Hoary Bamboo Rat is found at a broader range of elevations of 100-4000 m. In China, individuals appear to move among habitats seasonally, preferring large bamboo groves, secondary forest, and shrub forest in spring and summer and sparsely forested regions with silvergrass (Miscanthus sinensis, Poaceae) or forked ferns (Dicranopteris, Gleicheniaceae) in autumn and winter.
Food and Feeding. Hoary Bamboo Rats feed on roots and shoots of bamboo, beardgrass,silvergrass, and occasionally other plant types. Individuals generally feed on plants within 5-10 m from their burrow entrance. Food may be eaten outside the burrow or dragged back into the burrow. Stalks are held in place by front paws, while outer layers are stripped by incisors. Food is consumed in a manner where upper incisors are held motionless, lower incisors plane the object, and food is chewed by molars. Small uneaten nubs remain after feeding. Captive individuals manually remove cylindrical fecal pellets using incisors and toss them into dung piles. Presumably similar behavior occurs in the wild either in a toilet chamber, or fecal pellets are brought to the toilet.
Breeding. A female Hoary Bamboo Rat in estrus does not seal her burrow entrance, and a male moves in to breed. Breeding occurs year-round but peaks in November— December and March—June. Females line nest chambers with dry grass. After gestation of 22 days, a female gives birth to a litter of 1-5 young. Young are born naked and weigh 35-40 g at birth. Eyes open after 28-30 days, and offspring grow a coat ofjet black fur. Weaning takes place 56-78 days later, and females appear to reach sexual maturity at c.160 days.
Activity patterns. The Hoary Bamboo Rat exits its burrow at night to feed on the surface. It appears to be less aggressive than the Chinese Bamboo Rat.
Movements, Home range and Social organization. Burrows of Hoary Bamboo Rats are relatively simple, containing a single entrance (rarely 2—4 entrances), characterized by a mound of dirt. A 1-2 m long tunnel connects the entrance to the nest chamber, which is 12 x 32 cm and often contains a store of food. A toilet chamberis located 20-40 cm from the nest chamber and a bolt-hole is present. Burrows are temporary; females with young may extend their time in a single burrow to just over a month. Burrows are primarily excavated with incisors; feet are used to push loosened dirt behind. The individual will then turn and push accumulated soil out of the entrance. Hoary Bamboo Rats are solitary except for breeding when males move into females’ burrows. Same-sex adult individuals are never found in the same burrow. Males forced to cohabit in artificial settings will fight and even kill each other. Conspecifics are attacked with bites to head, neck, and cheeks; wild males have been observed with scars in these areas.
Status and Conservation. Classified as Least Concern on The IUCN Red List and the 2016 China Red List. The Hoary Bamboo Rat is known from several protected areas. It is hunted for food and faces habitat loss in parts of its distribution, particularly in western areas. Populations in India appear to be declining and warrant protection.
Bibliography. Agrawal (2000), Allen (1940), Aplin, Lunde & Molur (2008), Corbet & Hill (1992), Ellerman & Morrison-Scott (1951), Jiang Zhigang et al. (2016), Molur et al. (2005), Smith (2008), Tanomtong et al. (2013), Xu Longhui (1984).
description: Published as part of Don E. Wilson, Russell A. Mittermeier & Thomas E. Lacher, Jr, 2017, Spalacidae, pp. 108-142 in Handbook of the Mammals of the World – Volume 7 Rodents II, Barcelona :Lynx Edicions on page 135, DOI: 10.5281/zenodo.6609100