Food and feeding habits of smooth-coated otters (Lutra perspicillata) and their significance to the fish population of Kerala, India

Feeding habits of smooth-coated otters Lutra perspicillata were studied by analysing spraints collected from around the Periyar Lake within the Periyar Tiger Reserve, Kerala, India. Remains were identified by the comparison of body parts with a reference collection of appropriate prey species. Two methods were used to estimate the proportions of different prey consumed: frequency of occurrence and score-bulk estimate. The number of prey types in a spraint varied between one and seven. More prey species were found during low water levels (March-April). Fish was the major prey, followed by frogs, crabs, birds and insects. Throughout the study, the exotic tilapia and European carp constituted the major prey in the diet. The quantity of native Deccan mahsheer and endemic Periyar barb in the diet was insignificant. A higher intake of bottom-dwelling catfish was observed during periods of low water, probably because of the increased efficiency of otters to forage at these levels. By consuming large amounts of exotic species, such as tilapia and European carp, otters might contribute to the control of the rapid expansion of these species in the Periyar Lake and adjacent water bodies in the reserve.