In recent years, developing urban areas have affected food abundance and the feeding grounds of birds. The article contains analysis of the Tawny owl’s diet during four years (2006–2009) from different types of the urbanized area: city, town (much smaller than city) and countryside – based on 356 pellets with 726 prey items. The main group of victims was Rodentia, common were also Apodemus agrarius and Apodemus sylvaticus. Other important groups in the diet were: Microtidae (especially species Microtus arvalis) and Aves. As a generalist, Tawny owl fits the diet to the actual resources in a very flexible way. The main goal of the present work was to describe the food composition variability of the Tawny owl along with the degree of urbanization. Percentages of Microtus arvalis, Micromys minutus, Talpa europaea depended on the urbanization level, while Apodemus flavicollis, Insecta and Amphibia were related to the distance to nearest city centre. The study has shown that the diet of the Tawny owl has been changing along the urbanization gradient. It confirms earlier findings on high plasticity of foraging of this species in urbanized landscape.
This study evaluated the extent to which depth, sediment type, exposure to waves and coastal slope inclination modulate the relationships between regional nutrient loading, weather patterns and the species composition and dominance structure of macrobenthic invertebrate feeding groups in a brackish water ecosystem of the Baltic Sea. Irrespective of feeding function, the species composition and dominance structure of benthic invertebrate communities were determined by local abiotic variables such as exposure, depth and sediment type. Regional weather variables (average southerly winds, salinity, water temperature, ice conditions) either separately or interactively contributed to the variability of benthic invertebrates. Nutrient loading had significant effects on benthic invertebrates only in interactions with local abiotic or regional weather variables. Herbivores, deposit feeders and suspension feeders exhibited a stronger response to the studied environmental variables than carnivores. All this suggests that (1) the dynamic coastal habitats studied in this work are not very sensitive to shifts in nutrient loading and (2) local abiotic conditions and weather patterns largely define the observed biotic patterns. We believe that the benthic invertebrate time series will only be a better reflection of the nutrient loading signal if more years covering extreme events are included.
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