Comparison of the feeding habits of Eurasian otters on a fast flowing river and its backwater habitats |
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Authors: | J. Lanszki Z. Sallai |
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Affiliation: | aEcological Research Group, University of Kaposvár, Kaposvár, Hungary and Nimfea, Environment and Nature Conservation Association, Szarvas, Hungary |
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Abstract: | The diet and feeding habits of Eurasian otters Lutra lutra were studied by spraint analysis over a 2- year period, on three sections of the Drava River and three backwaters, in south-west Hungary. The primary food was fish (mean: 89.8% and 87.5% for riverine and backwater habitats, respectively); otters living in riverine habitats compared to backwaters, consumed more birds (3.9% and 0.7%, respectively), less mammals (0.5% and 0.9%, respectively), less reptiles and amphibians (5.6% and 10.2%, respectively) and less invertebrates (0.1% and 0.6%, respectively). In riverine habitats otters preyed more frequently on larger fish than in backwaters, but the main fish prey was small-sized (below 100 g in weight, 85.6% and 91.7%, respectively). On river sections they preyed more frequently on reophil (flow preferring fish, 18.9% and 3.3%, respectively), and less on stagnophil fish (stagnant waters preferring, 9.8% and 24.5%, respectively) than in backwaters. The main fish prey was eurytopic (tolerant of rivers and stagnant waters, 71.3% and 72.2%, respectively). Preference (by Ivlev's electivity index, Ei) in the Drava River for various fish guilds differed, as the otters preferred eurytopic (Ei= 0.30) and stagnophil fish (Ei= 0.24), and avoided reophil fish (Ei=−0.58). Otters did not threaten the rare, flow preferring fish species and the main diet consisted of economically unimportant species. |
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Keywords: | Lutra lutra fish electivity, Drava, Hungary |
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