Diet of the European otter (Lutra lutra) in the Massif central (Auvergne, France): spatial and seasonal variations between two study sites

Abstract

In order to evaluate predation strategy and variations during an active population dynamic, diet of European otter (Lutra lutra) was studied during a year-round cycle in two different aquatic systems in Auvergne (France). First were tributaries of Allier River in Haute-Loire and second were marshes, creeks, rivers and ponds in Puy-de-Dôme. Preys were identified and quantified (occurrences, abundances and biomasses) from otter spraints sampling. Diet was mainly consisted by little- and medium-sized fish (74% to 89% of consumed biomass, size generally less than 17.5 cm). Dominant prey in otter’s diet were the most numerous species in studied rivers and marshes, which corresponds to the most efficient predation strategy. Crayfish, amphibians, reptiles and small mammals constituted most of time secondary prey, but sometimes dominated diet. Spatial and temporal differences in prey diversity, abundances and biomasses were recorded. Data illustrating species diversity in rivers and marshes recently recolonized by European otter were not modified by its predation impact. The study of a top-predator diet can therefore be considered as an additional way in habitats studying and biodiversity and management conservation strategies, in natural or anthropogenic alteration contexts.