The usual English name for this species being rather clumsy, I prefer to call it simply the smooth otter.
I met it for the first time in Thailand, where, on the ample sandbanks of the wide, shallow Huai Kha Khaeng river close to the Burmese border, I had found the tracks of tigers, peacocks and elephants, as well as those of three different species of otter: Eurasian, small-clawed and smooth, clearly distinct. One late afternoon, when I was quietly walking along the bank, I suddenly noticed two otters swimming upstream, large and quite conspicuous. They were unmistakably the smooth otter, large and rather boisterous. They also put on a display of cooperative hunting such as I had never seen in any other otter species.
In the shallow current across the sands, fish were darting across, fast and quite uncatchable. The otters swam parallel, rapidly under and at the surface, one animal slightly behind, zigzagging across the wide river. Along the bank opposite was a narrow zone of reeds, and, as a joint strategy, the otters with their boisterous approach scared the fish in front of them into the reeds. Once the otters themselves arrived there, they dived into the vegetation, several times catching a fish and eating it on the spot, then off again in another zigzag, arriving at the reeds a bit further upstream for another meal. Two kingfishers accompanied the otters, picking off escaping small fish in the shallows.
The smooth otter is known only sparingly; remarkably, it shows similarities with the giant otter, on a different continent, and the two may be closely related. It occurs throughout most of the Indian sub
continent and south-east Asia, as far down as Sumatra, and with a curiously separate population in the Iraqi marshes (Fig. 2.19). It is an animal of larger water bodies, especially rivers and dams, favouring rocky shores or banks with dense vegetation, also occurring along sea shores and in mangrove areas. Where I found it together with other otter species, the smooth otter was the one most often in the lower, slow-flowing parts of the river, and in dams.
Smooth otters are robust animals, quite a bit larger than the Eurasian otter, though not the size of the giant otter, with a total length of up to 130 cm. They have unusually large feet, a broad, somewhat flattened tail, and a large nose. The guard hairs in the fur are quite short and smooth, and the colour is that of the usual otter, a dark brown that is rather variable between populations, light underneath, often with a clear demarcation. Also they have a well developed set of whiskers.
Smooth otters share their geographical range with several others, but when present in an area they are the most conspicuous. Partly this is because of their social habits: they are rarely alone, but usually go around in groups of up to ten animals (occasionally more; on average about five). The composition of such groups varies, in variations on the theme of a female with her cubs, sometimes from several years. There may be a male with them, but not always, and sometimes the group consists just of sub-adults and cubs of the year. The litter size is two to four, but little is known of reproduction in the wild.
I noticed that, when slightly alarmed, smooth otters strikingly rear up on their haunches and look around. The Eurasian otter is never seen doing this, except in captivity.
Rather than seeing the animals themselves, in any one area the give-away for the presence of smooth otters is the scats along the banks, as for most otter species. In this case the 'spraint' sites are difficult to overlook, as often they are large and the spraints themselves remarkably smelly (of rotting fish), even over a considerable distance. The larger spraint sites have quantities of faeces, spread out and flattened by otters rolling, rubbing and scraping, somewhat reminiscent of the giant otters' campsites.
On such spraint sites the nature of the diet of smooth otters is evident: there are fish scales everywhere. The food is dominated by fishes, and quite large ones at that, up to 45 cm long (mean size >15 cm), but they also take crabs, frogs and the odd snake. For preference, smooth otters take the rather slow-moving fishes, or those living in large, dense shoals. Where they occur in the same areas as Eurasian and small-clawed otters, the smooth otter is the most piscivorous, taking the largest prey, often as socially organized foragers, more cooperative than any of the others.
Little is known of their populations, numbers, mortality and reproduction. By all accounts, however, the number of smooth otters in any one area is small and their density low, but, as with the giant otters, the animals are conspicuous. It is likely, therefore, that they are even more vulnerable to human interference than the others. They are poached for their fur, and skins are traded in large numbers. In many areas people eat them, and the animals make themselves unpopular by tearing nets and taking the fish. They face a world of human dangers.
General references for smooth otters
Hussain and Choudhury 1995, 1996, 1997, 1998; Kruuk etal. 1994a; Sivasothi and Nor 1994.
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