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

Romanowski Jerzy, Lesiński Grzegorz

Polish Journal of Ecology

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2019

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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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Analysis of microsatellite polymorphism and genetic differentiation in urban and rural kestrels Falco tinnunculus (L.)

Rutkowski Robert, Rejt Łukasz, Szczuka Anna

Polish Journal of Ecology

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2006

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Vol. 54, nr 3

473-480

EN

The European Kestrel Falco tinnunculus (L.) is commonly observed in urban-industrial environment. Colonization of cites by the species was shown to be interlinked with changes in its ecology and breeding biology. Such adaptations can lead to isolation of urban populations from rural birds. In this paper we investigated genetic differentiation between birds from centre of Warsaw (Centre Group), suburban area of the city (Suburban Group) and one rural area (Rural Group). We analyse polymorphism of six microsatellite loci in 56 kestrels. The results shown moderate and significant differentiation between Centre and Rural groups and intermediate differentiation among Suburban and two other groups. Although our study is based on small number of individuals and only one rural sampling site, it suggested some level of isolation between city and rural environment. We assumed that observed differentiation might be the result of Urban Island system of appearance and maintenance of kestrel population in Warsaw. We also suspect that suburban areas of the city form a 'zone of admixture', where genes from the city and non-urban populations are 'meeting'.

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Does egg sex ratio in Urban Kkestrels (Falco tinnunculus) differ from parity?

Rejt Ł., Gryczyńska-Siemiątkowska A., Rutkowski R., Malewska A.

Polish Journal of Ecology

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2005

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Vol. 53, nr 4

545-552

EN

Paper tests the hypothesis that urban kestrels (Falco tinnunculus) are sex biased connected with urbanization gradient (central zone vs suburbs), laying date and level of PCB-contamination. Blood samples of 158 nestlings were collected on FTA cards. Sex of nestlings was determined using a multiplex PCR technique. Egg sex ratio among kestrels in Warsaw (Poland) was 51% and did not differ significantly from parity (n = 34 nests). Among broods at the beginning and at the end of the breeding season proportion of males was significantly higher than in the middle of the season. Sex ratio was significantly different along the urbanization gradient. Proportion of males in broods at the central zone reached only 44% contrary to the external zone where males composed 65% of chicks. Possibly influence of laying date, female condition as well as population size and isolation is discussed. For assessing the level of PCBs small amount of blood (approximately 1 mm3) was collected from the brachial vein from 83 individuals (17 nests). All samples from a particular nest were pooled together to increase the possibility of successful analysis. Among most broods (pooled data for nests with complete and partial hatching) contamination of PCBs in nestlings. blood was low (average level of PCBs was 55.1 ppm, range: 0-252.8). A trend toward decreasing proportion of males among broods with higher PCB-contamination was found to be insignificant. Probably level of organic contamination in chicks. blood depends more on pollution existing in rural hunting areas and is not directly connected with nest site and its close vicinity.