Aonyx cinereus

37. Asian Small-clawed Otter Aonyx cinereus French: Loutre cendrée / German: Zwergotter / Spanish: Nutria chica Other common names: Oriental Small-clawed Otter Taxonomy. Lutra cinerea Illiger, 1815, Batavia, Indonesia. Three subspecies are recognized. Subspecies and Distribution. A. c. cinereus Illiger, 1815 — S & SE China (including Hainan), Mainland SE Asia, Philippines (Palawan), Borneo, Sumatra, and Java. A. c. concolor Rafinesque, 1832 — Sub-Himalan zone in Nepal, Bhutan, NE India, N Myanmar, and SW China. A. c. nirnai Pocock, 1940 — SW India. Descriptive notes. Head-body 36-44 cm (males), 43: 2-46.8 cm (females), tail 22.5-27 cm (males), 26-27.5 cm (females); weight 2: 40.3-80 kg. Asian Small-clawed Otters are the smallest of the world’s otter species. They have long bodies and short legs, and dorso-ventrally flattened tails. The pelage is uniformly brown exceptfor the neck, throat and chin, which are grayish-silver, sometimes almost white. The head 1s quite small, with eyes that are proportionally larger than in other otters. There are two pairs of mammae. Claws are present but reduced on all the feet; the webbing on all the feet is incomplete. The skull is small, short and wide. Dental formula: 13/3, C1/1,P 3/3, M 1/2 = 34. Thefirst premolars are usually absent. The upper and lower carnassials and the upper molar are very large. Habitat. Asian Small-clawed Otters are found along lakes and rivers, in coastal wetlands, marshes, mangroves, and rice fields. They sometimes occur close to human settlements. Food and Feeding. The diet is primarily crabs and shellfish. Fish, amphibians, snakes, small mammals, and insects are also eaten. In Thailand, 95% of spraints contained the crab Potamon smithianus, 40% contained amphibians and fish, 15% contained small mammals, and 5% contained arthropods. The size of crabs consumed by Asian Smallclawed Otters reflects what is available in the watershed they inhabit. Asian Smallclawed Otters coexist with Eurasian, Hairy-nosed, and Smooth-coated Otters in numerous locations, including severalriver systems in Thailand and Malaysia. Although all three species consume the same prey, the Asian Small-clawed Otter is predominantly a crab eater, whereas the other species consume mostly fish. Prey are captured mostly by sight, but also by touch, using their dextrous forefeet. Shellfish are dug up and left in the sun so that the heat causes them to open, allowing Asian Small-clawed Otters to consume them without having to crush the shells. Activity pattern. Primarily diurnal, although reported to be nocturnal or crepuscular when found close to humans. During the day, Asian Small-clawed Otters often rest and groom on grassy or sandy banks near water. In marshes, they use mostly islands. Resting sites often show signs of spraint smearing, a behavior also observed in captivity. Defecation sites used by the Asian Small-clawed Otter occasionally are shared with Eurasian and Smooth-coated Otters and thus cannot be differentiated with certainty. Asian Small-clawed Otters have a diverse vocal repertoire that includes at least twelve different sounds, such as alarm, greeting, and mating calls. Movements, Home range and Social organization. Asian Small-clawed Otters are playful and sociable animals, and often travel and forage in groups of up to 12-13 individuals. In captivity, they can swim underwater at speeds of 0-7- 1-2 m /s. Breeding. Asian Small-clawed Otters are monogamous and both parents help in raising the offspring. In captivity, females come into estrus every 28-30 days and estrus lasts three days. Gestation is c. 60 days. Females in captivity build a nest of grass two weeks before parturition. One pair may produce up to two litters per year. Litter size can be up to seven, but averages four. Neonates weigh about 50 g and measure around 14 cm in length, and are covered in silver gray fur. The eyes are closed until the fifth week. The young learn to swim at seven weeks of age, and attain sexual maturity during their first year. In captivity, males spend more time maintaining the nest, whereas females spend more time grooming and training young. In the wild and in captivity, oldersiblings may help raise offspring. Status and Conservation. CITES Appendix II. Classified as Vulnerable in the. Asian Small-clawed Otters are threatened by habitat destruction and pollution from organochlorines. Local persecution may also affect populations where they are perceived as competitors for fish resources. In parts of Asia, their organs have traditional medicinal value. Very little is known about the ecology of this species and field studies are needed. Bibliography. Foster-Turley & Engfer (1988), Francis (2008), Kruuk et al. (1994), Lariviere (2003a), Leslie (1970), Medway (1969), Nor (1990), Shariff (1985), Wozencraft (2005, 2008), Yoshiyuki (1971).Published as part of Don E. Wilson & Russell A. Mittermeier, 2009, Mustelidae, pp. 564-656 in Handbook of the Mammals of the World – Volume 1 Carnivores, Barcelona :Lynx Edicions on page 646, DOI: 10.5281/zenodo.571404