Lanszki József - Ábrahám Levente (szerk.): Vadon élő vidrák Magyarországon - Natura Somogyiensis 14. (Kaposvár, 2009)

WILD LIVING OTTERS IN HUNGARY (SUMMARY)

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%o and 72.2%, respectively). Preference (by Ivlev's electivity index, Ej) in the Drava River for various fish guilds differed, as the otters preferred eurytopic (E—0.30) and stagnophil fish (E

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=0.24), and avoided reophil fish (E—-0.58). Otters did not threaten the rare, flow preferring fish species and the main diet consisted of economically unimportant species. Diet composition of otters living on small watercourses in south-western Hungary The diet composition of otters was studied by spraint (faecal) analysis (n=1460 samples), over a two-year period, on five sections of stream and channel in the Drava region of south-west Hungary. The primary food item of otters was generally fish (range: 33.389.9%, biomass estimation), with amphibians of secondary importance (3.4-48.5%). Highest fish consumption was found in winter and lowest in spring. Amphibians were eaten more in spring than in winter. Mammals (range 2.0-9.3%), birds (1.1-4.1%), reptiles (up to 22.2%), crayfish (up to 1.7%) and insects (0.1-4.2%) were consumed at low levels. Trophic niche breadth did not differ significantly between areas, though the widest and lowest seasonal values differed greatly (summer B=2.48, winter B=1.12). Otters preyed mainly on small fish (<1

00 g in weight, range 88.0-96.9% biomass) in all study areas. Eurytopic (mean 72.7%) and stagnophilic fish (mean 21.7%) were taken preferentially, with lesser consumption of reophilic species (mean 5.6%). Non-native fish were taken most often (mean 71.0%, e.g. giebel carp, brown bullhead). Results indicated that small water courses can play an important role as regards otter habitat and, as such, should receive more attention when assessing habitats for otter. Feeding habits of otters living on three moors in the Pannonian ecoregion Diet composition and feeding habits of Eurasian otters living on three moors (Baláta, Nagyberek and Fehérvíz) in Hungary were studied over two years using spraint analysis (n=199, 503 and 315 samples from the three moors, respectively). The food and presence of otters in the first moderate and second drought year, when the moors dried during the summer period, generally differed. Area-dependent variations in the diet were also found. The primary food source was fish (biomass estimation for the first and second year: Baláta 94.4% and 99.9%; Nagyberek 93.9% and 71.5%; Fehérvíz 66.4% and 82.1%). Most fish (mean: 94.6-99.9%) were small-sized (<100 g in weight), and the most frequently taken species was Carassius spp. On moors, which are dependent on rainfall and ground-water only, during or after periods of drought otters temporarily changed their diet from optimal prey (fish) to sub-optimal prey (e.g., waterfowl) and they often left the habitat entirely. On moors with small canals, during periods of drought otters kept fish as the dominant food source, and weathered out extreme environmental local conditions. Diet of otters living in three different habitats in Hungary? The seasonal diet composition of Eurasian otters living by an eutrophic fish pond system, a wetland alder forest, and a slow-flowing stream located in south-west Hungary was investigated by spraint analysis (n=801, 116 and 234 samples respectively). Both percentage relative frequency of occurrence (%0) and biomass (%B) of food items (calculated by coefficients of digestibility) were estimated. The food composition of the