Diet of the Southern river otter in Argentinean Patagonia

FASOLA L., GOZZI, A.C., MALMIERCA, L., CHÉHEBAR C., MACDONALD, D.W., CASSINI M.H.

Hwacheon, Corea del Sur

Simposio; IUCN Xth International Otter Colloquium.; 2007

Southern river otter, Lontra provocax, is endemic from Argentinean and Chilean Patagonia. In Argentina, there are two populations, one in northern Patagonia occupying the Limay river basin, and the other one in southern Patagonia, in the Beagle channel. Recent studies indicated that for most species of otters, population abundance and distribution is constraint by food availability. Thus, studies on foraging ecology can provided key information for otter conservation. The objectives of this paper were to describe present diet of the species along its Argentinean geographic range; to analyse differences in the diet between seasons and years; to compare with Chilean populations and with other species of otters; and to evaluate the relationship between diet requirements, diet composition and habitat use in Patagonia. We analysed 254 spraints of otters collected between 1983 and 2006. Macro-crustaceans dominated the freshwater diet while fish did so with sea diet. In northern Patagonia, there were no significant differences in diet composition between 1983 and 2005, and between water bodies; in winter, otter ate more fish and fewer crustaceans than in summer. In southern Patagonia, there were no differences between years or seasons. As most species of otters, L. provocax showed high level of specialization in slow prey, mainly benthonic fish and macro-crustacean. Agreement between the historical distributions of otters and that of crustaceans suggests that the specialisation in crustacean consumption in freshwater is an old adaptation of the species, and that they are a critical resource for otter survival.