Abstract
The present study was based on the analysis of spraints (n = 294) collected between December 2005 and November 2007. The importance of each type of prey was determined by absolute and relative frequency. Niche breadth was also estimated. The results were reported as mean (± SD) of relative frequencies. Fish were the main prey found in spraints (57.8 ± 7.0%). Fish from Callichthyidae family were the main prey, followed by Cichlidae, the species Hoplias malabaricus and the family Characidae. The frequencies of other fish and taxa were lower than 13.9% (absolute frequency) and 5.6% (relative frequency). Despite significant seasonal variations, (P = 0.001), niche breadth values were low in all seasons (0.39 ± 0.11). Therefore, Lontra longicaudis presented a narrow niche breadth as a result of consistent fish predation. Based on these data, fish with rapid movement presenting territorial behavior and benthic fish with slow movements are the most consumed. Seasonal fluctuations are caused by the increase of secondary prey in the diet during some seasons.
Highlights
There are 13 currently recognized otter species in the world (Kruuk 2006)
The present study aims at characterizing the feeding spectrum, seasonal variation and niche breadth of L. longicaudis in the Lower Arroio Grande River, southern Brazil
The average (± SD) relative frequency per season shows that fish was the most frequently consumed item, representing 57.8 ± 7.0% of all prey items; it was followed by rodents with 20.1 ± 13.0%
Summary
There are 13 currently recognized otter species in the world (Kruuk 2006). The Neotropical otter Lontra longicaudis (Mustelidae: Lutrinae) has a wide geographical distribution; it occurs from northern Mexico to Argentina and Uruguay, including most of the Neotropical region, except for Chile (Larivière 1999). Its distribution includes areas of different climates and habitats: Despite its large distribution in Latin America, L. longicaudis has been poorly studied and is considered as a ‘virtually unknown’ carnivore (Mason and Macdonald 1986, Kruuk 1995, 2006). Most of the published information about this species is related to its feeding habits; most studies have been carried out in Brazil, mainly in the southern region. Studies in southern Brazil have covered different aquatic environments, such as the estuarine region and lagoon of Florianópolis
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