Volume 18A Proceedings VIIIth International Otter Colloquium, Valdivia, Chile

Citation: Hájková, P.  (2001) Diet of Otters (Lutra lutra) in the Upper Hornád River Catchment, Slovakia. Proceedings of XIIth International Otter Colloquium, IUCN Otter Spec. Group Bull. 18A: 16

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Diet of Otters (Lutra lutra) in the Upper Hornád River Catchment, Slovakia

Petra Hájková¹

¹Department of Zoology, Comenius University, Mlynská dolina, 842 15 Bratislava, Slovak Republic e-mail: hajkova@ivb.cz

ABSTRACT

The diet of otters (Lutra lutra) from 2 sites in the Slovenský Raj National Park (the upper Hornád River catchment, Eastern Slovakia) was studied by spraint analysis. A total of 320 spraints, collected monthly between June 1999 and May 2000, were analysed. Eight fish species and 5 non-fish prey categories were identified. Trout (Salmo trutta m. fario) was highly dominant at both sites, being found in 95 % of all samples. The second most important prey was different between sites; at site 1 (Hornád River) grayling (Thymallus thymallus) predominated, whilst at site 2 (Vernársky Brook) bullhead (Cottus poecilopus) and frogs were second in importance. Non-fish prey was seldom taken; crayfish, reptiles, birds, and mammals were very rare, only frogs were more frequent.

Results are also presented in terms of biomass, produced using regressions for bone length/fish length and fish length/fish weight for the 3 most important species (trout, grayling, bullhead). The regressions were calculated using fish caught at the 2 study sites and at the adjacent parts of the Hornád River catchment.

Results from spraint analysis are compared with fish availability estimated by electrofishing. Seasonal changes and differences in the diet composition between sites are discussed.

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