Nutrition
The Asian small-clawed otter is a carnivore, but unlike others within the subfamily of Lutrinae, its main source of energy and nutrition is not always from fish. Major prey organisms for Aonyx cinereus vary, depending on location. In a Thai study by Kruuk (1994, 31) their diet was found to be “dominated totally by freshwater crab Potamon smithianus, with a few frogs and fish thrown in."
Fig. 11. Occurrence of different prey categories in spraints of small-clawed otter Aonyx cinerea, smooth otter Lutra perspicillata and common otter L. lutra, (Image by Kanchanasaka, B., Kruuk, H., O’Sullivan, S., and Wanghongsa, S. “Niche Separation in Three Sympatric Otter Lutra Perspicillata, L. Lutra and Aonyx cinerea in Huai Kha Khaeng, Thailand,” Biological Conservation [1994]: Vol. 69.1, 118.)
Kanchanasaka et al. (2006, 118) also included A. cinereus in their observations of the diet and habitats of three Otter species in Thailand. It was found that this species prefers to hunt mostly in the middle of a river, but was also found in the upper, rapidly flowing section. Additionally, their spraints, or otter dung, contained mostly remains of small crabs, as indicated in figure 11.
However, access to extensive mudflats in the Bangladesh Sundarbans has allowed these otters to adapt their preferred diet from crabs to Mudskippers. When examining here, Aziz (2018, 7) found that two samples were exclusively fishbones, while a third contained a mixture of fish and crab. During this study, it was also observed that their strategy to catch these fish has been developed for success (figure 12). Mudskippers congregate in burrows during the tide, allowing otters to insert their forearm
into one end of the burrow, and catch them as they are flushed out the other end.
In captivity, these otters are given a wide range of foods, which are chosen based on their carnivorous wild diet. These include small fish, crabs, mussels, live crayfish, live goldfish, clams, and even chicks, as seen in figure 13. According to the experts at the Smithsonian’s National Zoo (n.d.) they are also given canned feline diet and kibble, which prohibits the growth of kidney stones, which they have a propensity to develop.
Fig. 12. Asian Small-clawed Otter searching for mudskippers on exposed mudflats, (Image by Aziz, A.M. “Notes on Population Status and Feeding Behaviour of Asian Small-Clawed Otter (Aonyx Cinereus) in the Sundarbans Mangrove Forest of Bangladesh,” IUCN/SCC Otter Specialist Group Bulletin, [2018]: Vol. 35.1, 6.)
