We studied the diet of the American mink (Neovison vison) in small artificial watercourses located in a farmland area of the valley of the River Barycz in Poland. Rodents, mainly Microtus spp., were the most frequent prey identified, occurring in 88.3 % of all analyzed mink scat. Minks also fed willingly on fish, birds and amphibians, whereas insects, crayfish and reptiles accounted for only a small part of the biomass of food consumed. The food niche breadth of the mink’s diet was wide, and varied significantly between seasons; in spring and autumn minks preyed mainly on rodents and fish, while the winter and summer diets consisted of a broad characterization of prey items. The proportion of mammals in the diet also decreased significantly during the summer months. These patterns differ from those previously reported in Europe, and demonstrate the plasticity of the mink diet across habitats.
The diet of the polecat (Mustela putorius) was studied by analysing 1078 scats collected in extensive farmland in Poland between 2006 and 2008. The diet included a wide variety of prey species; the main component were rodents (51.7 % of biomass), mainly Microtus arvalis. Birds were the second most common group in the diet (%Fr = 4.5). Anurans, reptiles, invertebrates and other items were additional elements of the diet. Seasonal comparisons reveal differences in diet. Rodents and birds were exploited throughout the year. Other mammals and carrion were the main component of a winter diet, whereas in spring amphibians and reptiles were characteristic prey. Diet of polecat from the studied agricultural landscape in Poland was more similar to diet of population from Hungary than to France. All these patterns confirm that polecat is a food generalist with almost exclusively carnivorous diet and can easily exploit different food resources.
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.
Sex skewed kleptoparasitic exploitation of kestrel Falco tinnunculus was studied on foraging areas in south-east Poland. All kestrel prey subject to kleptoparasitism attempts were small mammals caught by kestrels hunting by hovering.. Kleptoparasites attacked male kestrels more frequently than females. Males did not defend their prey as vigorously as females but males were more efficient at capturing further prey following loss of prey. Males also seemed to select habitats that facilitated more effective foraging which reduced costs of lost prey. Kleptoparasitism on kestrels was more successful by groups than by individual attackers.
A three-year experimental study with artificial ground nests was carried out in a highly fragmented agricultural landscape in Southern Bohemia, Czech Republic, to examine whether population density or spatial distribution of active black-billed magpie (Pica pica) nests contributes to the pattern of predation on dummy nests. Out of the total of 335 dummy nests with a known fate, predators robbed 126 (37.6%). The population density of magpies did not affect nest predation significantly, while nests placed closer to active magpie nests were predated significantly more than distant nests in two out of the three years under study. Moreover, the distance to the nearest active magpie nest was found to be the most obvious factor affecting nest predation risk, among such factors as site, individual nest position, habitat type, distance to the nearest forest fragment, habitat diversity, nest concealment, distance to the nearest line habitat, and distance to a perch for avian predators. The study suggests that the spatial pattern of a dominant generalist predator can be a factor explaining the predation pattern on experimentally treated nests.