The diet of otters was studied by the means of spraint analysis in the Bieszczady Mountains, in southeastern Poland. The study area extended over 25 km long stretch of the River San, about 1 km above Solina dam reservoir. Spraints were collected on seven 2 km long sections in 1993, and on three sections in 2010. In both study periods, otter spraints were collected in August, when the weather conditions were similar. The study revealed high contribution of mountain fish species such as Phoxinus phoxinus,Cottus spp., and Barbatula barbatula in otter diet. Diet composition along the River San showed little variation in 1993, except from the section closest to dam reservoir where it was characterised by the highest frequency of occurrence of perch Perca fluviatilis, cyprinids and amphibians. The share of perch in otter diet decreased, while that of noble crayfish Astacus astacus increased with the distance from Solina reservoir.
Changes in otter diet between 1993-2010 were characterized by an increase of the consumption of perch and cyprinids on the one hand,
and a decrease of the consumption of crayfish, on the other. Both spatial and temporal changes in otter diet reflected the effect of Solina
reservoir on the river community and the availability of prey to otters. The results indicate the ongoing changes in fish community influenced by the construction of Solina reservoir.
The diet of otters Lutra lutra was studied by spraint analysis in six river and stream habitats in eastern Poland. In all of them fish were the staple food of otters, constituting from 29 % to 96 % of prey consumed in particular seasons. In upland (river Tanew) and mountain (river San, streams Dwernik and Głęboki) habitats, bullheads (Cottus gobio) were the most frequently eaten fish throughout the year (with maximum contribution of 57 % in the winter diet on river Tanew). In these habitats otters preyed on total of 10 fish species, including: brown trout (Salmo trutta), stone loach (Barbatula barbatula ), brook minnow (Phoxinus phoxinus) and stickleback (Gasterosteus aculeatus). On the lowland rivers, otters relied on more fish species than on the upland and mountain rivers (14 species on river Czarna Hańcza and 12 species on the upper and lower course of river Biebrza). Beside various cyprinids, otters preyed on stickleback, perch (Perca fluviatilis), mud loach (Misgurnus fossilis), burbot (Lota lota) and pike (Esox lucius). On all rivers, except the lower Biebrza, most of fish (from 70% to 88%) captured by otters were less than 10 cm long. Amphibians and crayfish were two other important groups of prey. On small streams in the Bieszczady Mountains, frogs (mainly Rana temporaria) comprised up to 46% of otter prey. Crayfish (Ortonectes limosus) remains were recorded in otter spraints only on the lowland rivers: in summer crayfish comprised 52% of prey on the Czarna Hańcza River and 47% of prey on the upper Biebrza River. In upland and mountain habitats the food niche breadth of otters was lower (from B=2.62 to B=6.12) than on the lowland rivers (from B=3.10 to B=11.09) and did not differ much between the seasons. On the lowland rivers the food niche breadth was high in winter and low in summer, and the seasonal differences in otter diet were much more pronounced as compared to the upland and mountain habitats.
The number of little owls, Athene noctua is decreasing in many European countries. In order to evaluate causes of the decline in Poland, habitat preferences of this species were analysed. Using GIS methods, 25 settled territories of the little owl, recorded during field surveys between 2000 and 2005, were compared with 50 unsettled locations. It was found that the proportion of built-up areas was higher in the occupied territories than in the random locations. No differences in grassland, forest and field proportion, habitat diversity and edge length were recorded between the occupied, and the random locations. The amount of forest and the proportion of built up areas appeared to be the best predictor of the occurrence of the little owl. Next, habitat use at 7 additional territories, which were occupied by little owls in 1980–90s and later abandoned, was analysed. In 2006, as compared to the period 1980–90, numbers of pollard willows decreased, whereas the number of buildings increased in these territories. The overall results lead to a conclusion that the little owl shows a high degree of habitat plasticity. The decrease of the area of grasslands and numbers of pollard willows is not likely to explain the population decline of the species.