Ábrahám Levente (szerk.): Válogatott tanulmányok V. - Natura Somogyiensis 17. (Kaposvár, 2010)

LANSZKI, J., MÓROCZ, A. & CONROY, J. W. H.: A vidra (Lutra lutra) kora tavaszi táplálék-összetétele a Gemenci Tájegység (Duna-Dráva Nemzeti Park, Magyarország) természetes élőhelyein

Natura Somogyiensis 17 315-326 Kaposvár, 2010 Diet of Eurasian otters (Lutra lutra

) in natural habitats of the Gemenc Area (Danube-Drava National Park, Hungary) in early spring period JÓZSEF LANSZKI

1, ATTILA MÓROCZ

2 & JIM W. H. CONROY

3 'University of Kaposvár, Department of Nature Conservation, RO. Box 16, H-7401 Kaposvár, Hungary; e-mail: lanszki@ke.hu 2Danube-Drava National Park, Tettye Sqr. 9, H-7625 Pécs Tettye tér 9., Hungary 3IUCN Otter Specialist Group, Celtic Environment Ltd. Old Mart Road, Torphins, Aberdeenshire, AB 31 4JG UK LANSZKI, J., MÓROCZ

, A. & CONROY, J. W. H.: Diet of Eurasian otters (Lutra lutra) in natural habitats of the Gemenc Area (Danube-Drava National Park, Hungary) in early spring period. Abstract: The relationship between the food web and interspecific trophic levels are less well understood along the Hungarian section of the Danube River. In this study, the diet composition of the Eurasian otter (Lutra lutra) as mammalian top predator species of wetlands was examined by spraint analysis, in an early spring period at six oxbow lakes of the Gemenc Area. The primary food of otters was fish (min-max 83.9100.0%, biomass estimation), characteristically gibel carp. Besides fish, amphibians, crayfish and water beetles were eaten in low proportions, therefore the trophic niche was very narrow in all areas. Otters preyed primarily (>56%) on small-sized (<100g) fish, but at three areas, the consumption ratio of 100-500 g fish was also considerable. The main fish prey was eurytopic (>69%), but stagnophilic or reophilic fishes were also eaten considerably on some areas. Consumption of fish in high proportions indicates that their availability might be satisfactory for otters. However fish surveys ocassionally indicated low fish densities. Diet composition and feeding habits of otters differed between areas. It draws attention to the possible need for different conservation and management objectives of the sensitive valley flat-habitats of the Danube, an important European ecological corridor. Keywords: oxbow, food habits, prey size, fish guild, spraint analysis, conservation Introduction The Gemenc Area of the Danube-Drava National Park is characteristically a floodplain - a largely forest-covered landscape (Fig. 1). In this area numerous branch and close to 30 relatively large oxbow lakes are located along the Danube River which is an important European ecological corridor. Due to the high biodiversity, large parts of the Gemenc Area is strictly protected and designated a Ramsar site, but local food web and interspecific trophic links have hardly been examined. The area supports a number of protected species such as: barbastelle bat (Barbastella barbastellus), pond bat (Myotis dasycneme), black stork (Ciconia nigra), white-tailed eagle (Haliaetus albicilla), black kite (Milvus migrans), wildcat (Felis silvestris), European beaver (Castorfiber) (I

VÁNYI & LEHMAN 2002, authors' observations).