Thryonomys gregorianus (Thomas, 1894)

Don E. Wilson, Thomas E. Lacher, Jr & Russell A. Mittermeier, 2016, Thryonomyidae, Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I, Barcelona: Lynx Edicions, pp. 331-333 : 333

2.

Lesser Cane Rat

Thryonomys gregorianus

French: Petit Aulacode / German: Kleine Rohrratte / Spanish: Rata de canaveral pequena

Other common names: Savanna Cane Rat

Taxonomy. Aulacodus gregorianus Thomas, 1894 ,

“Luiji Reru River, Konu, Kikuyu Country, British East Africa [= Kenya]. Alt. 5700 feet.” Restricted by C. A. Woods and C. W. Kilpatrick in 2005 to “00°35’S, 37°00'E.”

The Lesser Cane Rat is known since the Late Pliocene. Its oldest remains date to c. 3 million years ago from the Omo area (Ethiopia). Monotypic.

Distribution. Tropical C & E African species; it seems to occur from extreme N Cameroon, S Chad, W Central African Republic, S Sudan, South Sudan, W Ethiopia, N & SE DR Congo, Uganda, Kenya, Tanzania, Zambia, C & N Malawi, NW Mozambique, and NE Zimbabwe. More investigation is necessary because the geographical distribution is poorly defined.

Descriptive notes. Head-body 410-575 mm; tail 110-175 mm; weight 1.4-2.4 kg (males) and 1.7-1.9 kg (females). Lesser Cane Rats are large-sized rodents, only surpassed in Africa by porcupines ( Hystrix spp. ) and the Greater Cane Rat (71. swinderianus ). Overall morphology of the Lesser Cane Rat is very similar to the Greater Cane Rat, but it is smaller. Other differences include shorter length oftail of in the Lesser Cane Rat, its more protuberant nose, and position of grooves in upper incisors. Skull of the Lesser Cane Rat has a bar across the foramen oval thatis lacking in most Greater Cane Rats. Frontal of adult Greater Cane Rats has a triangular outline in dorsal view, butit is more or less square in the Lesser Cane Rat.

Habitat. Dry terrain in moist savannas up to elevations of 2600 m (e.g. on Mount Ruwenzori, Uganda). The Lesser Cane Rat is more terrestrial than the Greater Cane Rat, but neither lives in rainforests, dry deserts, or dry shrublands.

Food and Feeding. The Lesser Cane Rat is a monogastric herbivore. It usually feeds at night. It is a highly specialized and selective grass eater that shows preference for thinner and softer parts of grasses. Accumulations of cut grass stems and feces form welldefined paths that Lesser Cane Rats use between feeding areas and shelters. Diets of Lesser Cane Rats and Greater Cane Rats are similar. The Lesser Cane Rat particularly prefers elephant grass (Pennisetum purpurewm), but it also eats grasses in the genera Setaria, Hyparrhenia, Exotheca, and Melinis. Ginger ( Aframomum , Zingiberaceae ) is eaten in wet, wooded areas. Fallen fruit, bark, and roots are also eaten.

Breeding. Little is known about the breeding behavior of the Lesser Cane Rat, but it is supposedly similar to that of the Greater Cane Rat. A few pregnant Lesser Cane Rats have been recorded in May and November in Zimbabwe, August in Uganda, and November-December in Kenya. All of them carried 2-3 embryos. Litters are probably born within the cover of matted grasses.

Activity patterns. Activity patterns of Lesser Cane Rats are supposedly similar to those of Greater Cane Rats. The Lesser Cane Rat is predominantly nocturnal, but it can be somewhat diurnal. It alternates feeding with resting and followsits paths from shelters to feeding areas. Its shelter in tall grass provides hidden retreat from aerial predators. If vegetative coveris too sparse for protection, it shelters in abandoned holes of Aardvarks (Orycteropus afer) or springhares (Pedetes spp.) or in rocky crevices. In eastern Africa, the Lesser Cane Rat excavates shallow burrows.

Movements, Home range and Social organization. The Lesser Cane Rat can be solitary or live in small groups of up to c.12 individuals that may occupy a territory of 3000-4000 m? with good grass cover. As with the Greater Cane Rat, a family group of Lesser Cane Rats includes a dominant male, various females, and their offspring.

Status and Conservation. Classified as Least Concern on The IUCN Red List. As with the Greater Cane Rat, meat of the Lesser Cane Rat is considered a delicacy in tropical Africa, and it fetches high prices in the market. Although it is hunted as vigorously as the Greater Cane Rat, the Lesser Cane Rat is a smaller part of the meat market because of its smaller size.

Bibliography. Ewer (1968, 1969), Happold (2013b), Hayssen et al. (1993), Hoffmann (2008b), Kingdon (2015), Nowak (1999a), Shortridge (1934a), Skinner & Chimimba (2005), Thomas (1894), Van der Merwe (2004b), Van der Merwe & Bronner (2007), Wesselman (1984), Winkler (2003), Woods (1976, 1993), Wood & Kilpatrick (2005).

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Distribution. Tropical C & E African species; it seems to occur from extreme N Cameroon, S Chad, W Central African Republic, S Sudan, South Sudan, W Ethiopia, N & SE DR Congo, Uganda, Kenya, Tanzania, Zambia, C & N Malawi, NW Mozambique, and NE Zimbabwe. More investigation is necessary because the geographical distribution is poorly defined.