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Comparing Trophic Niches of Sympatric Raptors in Agricultural Landscape in Central Poland

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Romanowski J. , Lesiński G.

Polish Journal of Ecology

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2019

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tom Vol. 67, nr 4

331--338

EN

According to basic ecological principle, species that share the same niche do not occupy the same environment for a long time, and sympatry of two or more such species provides an interesting field for the analysis of their trophic niche differentiation. To examine the potential differences in the dimensions of the trophic niche we studied the diet of three sympatric avian predators that prey on colonial Microtus rodents. The study area in central Poland is located in an agricultural landscape, composed of crop fields, as well as meadows and pastures located within a small river valley. The pellets of long-eared owl (Asio otus), barn owl (Tyto alba) and kestrel (Falco tinnunculus) were collected from the 750 m2 study site including church building and its surrounding in the spring of 2016 and 2017. The analysis of pellets provided data on a total of 4128 vertebrate prey individuals (1914 from barn owl, 1749 from long-eared owl, and 465 from kestrel). The most important prey group of all three predators were small mammals (90%, 14 species) and the most frequently preyed species was Microtus arvalis (making up 72% of vertebrate prey of long-eared owl, 59% of kestrel and 53% of barn owl). Despite the general similarity in the diet composition, there were differences in the contribution of several prey species (e.g. Soricomorpha, M. arvalis, Mus musculus, Rattus norvegicus, and Apodemus spp.) and the diversity of the diet between the predators. We conclude that the trophic niches of the studied sympatric species differ in several dimensions, including diel activity, prey size and taxon-specific feeding preferences.

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Long-term decline of the Little Owl (Athene noctua Scop., 1769) in Central Poland

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Żmihorski M. , Altenburg-Bacia D. , Romanowski J. , Kowalski M. , Osojca G.

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tom Vol. 54, nr 2

321-324

EN

The population of Little Owl decreased over much of Europe including Poland, where it's status has not yet been elucidated in full. We compiled data from 13 censuses carried out from 1982-2005 at a 12 km2 study plot situated in an agricultural area in the north-western outskirts of warsaw in Central Poland. We observed a significant decline in the Little Owl population, leading to its disappearance from the study site. The population dynamics was not correlated with the weather factors analysed (snow cover and thickness, air temperature for December-March period, precipitation for March, May and June), which indicates that climate change was not a direct cause of the decline. There were no substantial changes in the land use structure at the study area. We conclude that the reduction in nesting sites and decreased food availability are the potential factors of the Little Owl decline.

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The determination of microplastic contamination in freshwater environments using sampling methods : A case study

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Karaban K. , Poniatowska A. , Kaliszewicz A. , Winczek M. , Ilieva-Makulec K. , Romanowski J.

Journal of Water and Land Development

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2023

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tom no. 57

140--146

EN

We compared different net sampling methods for microplastic quantitative collection by sampling different water volumes with nets of different mesh sizes. Sampling covered freshwater lake and reservoir with a significant degree of eutrophication located in Central Poland. The fibres were the main type of plastic collected from sampling sites and constituted 83% of all microplastic particles. Fibres of 700-1900 μm dominated in the samples. The size of mesh affected the amount of fibres collected. Small fibres of 10-200 μm in length were collected using only a fine net of 20 μm mesh size. The total amount of fibres depended on sample volumes; concentrations of microplastics were higher for smaller water volumes. It is likely that clogging with phytoplankton and suspended particles reduced the filtration capacity of the finest nets when large volumes were sampled, which led to an underestimation of microplastic. To our knowledge, this is the first study to provide evidence that the amount of small microfibres depends on mesh size and that the total microplastic abundance in freshwaters in Poland depends on the sample volume. We suggest sampling rather larger than smaller water volumes to assess the level of microplastic contamination more accurately, but clogging, which reduces the filtration capacity of finest nets, should be taken into account when eutrophic freshwater environments are studied.