Hábitos alimentares de Lontra longicaudis (Carnivora: Mustelidae) e sua relação com a disponibilidade de presas no Pampa Gaúcho

Abstract

The neotropical river otter (Lontra longicaudis) is a medium-sized mammal, is classified as almost threatened at the international level, presents an elusive behavior and, because of this, most of studies on the species are related to indirect methods, such as tool analysis and observation of other traces (eg. Mucus and scratches in the soil). The objective of the present study was to understand the feeding habits of L. longicaudis in two limnic systems, a creek and a river, both located at the Brazilian Pampa region.This study also sought the relationship between diet and fish availability in the studied areas. Diet analyses was made based on 349 scats collected in the two studied areas between august 2016 and march 2018. These feces were analyzed in the laboratory, from the residual contend, such as scales, hard spines, bones, teeth, exoskeleton fragments, feather and hairs. The items were categorized into seven main groups: fish, crustaceans, mammals, birds, insects, spiders and molluscs. Fish was the most important item in the diet for both areas, being presents in 91,4% and 96,7%of the samples. However, there was difference between the study areas in relation to the main predated fish families. In the creek the most important fish in the diet was Cichlidae and Loricariidae, while in the river, the most important fish was Cichlidae and Characidae. This difference is probably related to the environmental characteristics that results in different availability of certain preys. Despite differences in the main items consumed, there was agreement in the selectivity of preys considering the Rank Prefference Index, with the Callicthyidae and Cichlidae been a most preferred resource. The selection of these preys are probably associated to the habits of these fish that favors the predation.