Seasonal Diet of the Otter (Lutra lutra) On the Alazani River (Georgia)
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NACRES, Centre for Biodiversity Conservation & Research
Publish date: 2013-08-19
Hystrix It. J. Mamm. 2013;24(2):157–160
The seasonal diet of the otter (Lutra lutra) was studied on Alazani river in eastern Georgia using scat analysis. The frequency of occurrence (FO) of prey items and, for fish species, biomass consumed (BC) were estimated. Fish and amphibians made the bulk of the otter diet in the study area (49.8-30.0% FO and 23.6-36.2% FO, respectively). Reptiles were also important in otter diet (11.5% and 13.4%). Mammals, birds, insects, mollusks and crayfish were of minor importance. Crucian carp (Carassius carassius) and common carp were the most important fish in the otter diet. Among amphibians, only Rana ridibunda were found; among reptiles, only dice snake and grass snake were found in otter spraints. All mammals preyed upon by otters were rodents; mice (69% of all mammals) and muskrat (31%). Water beetles (Dytiscidae) and grasshoppers (Acridoidea) were the main group of insects consumed by otters. Seasonal food niche breadth change was expressed strongly (BA = 0.260 in cold season vs. BA = 0.492 in the warm season). Crucian carp predominated in the diet in both warm (37.9% BC and 52.0% FO, respectively) and cold season (90.4% BC and 82.0% FO, respectively). C. idella and S. glanis were found during the warm season but almost disappeared from the otter diet in the cold season. Rutilus rutilus and Hypophthalmiehthys molitrix were of minor importance in both seasons.