Wyniki wyszukiwania - Biblioteka Nauki

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Factors shaping a breeding bird community along an urbanization gradient : 26-year study in medium size city (Lublin, SE Poland)

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Biaduń W. , Żmihorski M.

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tom Vol. 59, nr 2

381-389

EN

We investigated the spatiotemporal dynamics of a breeding bird community in the urbanized landscape of Lublin city (150 km2, 0.5 million inhabitants, SE Poland). We conducted 211 separate territory mapping surveys during 26 years (1982-2007) in 24 green areas (0.2-30.1 ha in size), distributed along an urbanization gradient. We recorded a total of 16,151 territories of 65 species. According to the estimated species richness, we detected all the species present in the studied plots. The three species community indices (species richness, Shannon-Wiener index and abundance - number of breeding pairs in census plot) increased with increasing tree stand age and area of the site, while it decreased as the proportion of biologically inactive areas increased. The three indices showed significant negative trends as the study period progressed. The mean decreasing rate was 0.2 species and 2.3 territories per year. Distance to the city centre and understorey cover negatively affected bird abundance, while they positively affected species richness and the Shannon index. Tree stand age seems to be the most important of the three indices among the analyzed explanatory variables. Our results show that the diversity of breeding avifauna in an urbanized landscape can be significantly shaped by the proper management of vegetation and size of green areas in the city. The long term decline of the three diversity indices seems to be the most important outcome of our study and requires further research and monitoring.

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Long-term population trends of corvids wintering in urban parks in central Poland

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Mazgajski T. , Żmihorski M. , Halba R. , Woźniak A.

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tom Vol. 56, nr 3

521-526

EN

Changes in the numbers of corvids wintering in Warsaw (Central Poland), in the last sixteen years were analyzed. Four species were studied: Rook Corvus frugilegus L., Jackdaw C. monedula L., Hooded Crow C. corone cornix L. and Magpie Pica pica (L.) The results were based on density data for birds foraging in three urban parks. The bird counts were conducted in November and December 1988.2003. It was found that the number of wintering Rooks decreased significantly (0.5 fold), populations of Jackdaws and Hooded Crows - increased (4.25 and 3.95 fold, respectively), and no apparent trends were observed for Magpies during this period. Observed trends for Rooks as well as comparisons of limited data gathered earlier in other areas may confirm suggestions about the changing of migration routes of this species.

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Nest survival in a large river valley: an experiment using artificial nests on an island and bank of Vistula River (Poland)

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Żmihorski M. , Lewtak J. , Brzeziński M. , Romanowski J.

Polish Journal of Ecology

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2010

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tom Vol. 58, nr 1

197-203

EN

Predation pressure, which varies among habitats, is important factor for selection of nesting sites by birds. We investigated artificial nest depredation on an island 23 ha in size and on the river bank covered by willow-poplar forest and meadows in the middle Vistula river valley, in the spring and autumn 2006. We used polyurethane thrush-size nests placed at three heights (ground, bush and tree) with one quail egg. Each nest was checked twice, 7 and 14 days after the beginning of the experiment, in total 381 nest-inspections was included. Additionally, we live-trapped rodents (data from 510 trapnights included) which are potential predators of broods. We found that the survival rate of artificial nests was higher on the island as compared to the bank. Artificial nests placed on the ground revealed the higher survival rate than the nests placed on trees and bushes. Nest survival rate was higher in the autumn than in the spring. Repeatability of the results (survived vs. depredated) for the first and second 7-day period was high but lower on the island as compared to the bank. The abundance of rodents was higher on the bank during the spring, but no difference was recorded in the autumn. Rodents were also more abundant in the autumn than in the spring. This may indicate that survival rates of nests were not affected by rodents directly.

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Small mammals in the diet of the Tawny Owl (Strix aluco L.) in Central European Lowland

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Żmihorski M. , Balciauskiene L. , Romanowski J.

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tom Vol. 56, nr 4

693-700

EN

We analysed the variation of small mammal species composition in the Tawny Owl Strix aluco L. diet in forest habitats of Central European Lowland. We used published and unpublished materials from forest-dominated landscapes in Lithuania (n = 7 locations), Poland (n = 8) and East Germany (n = 1); marginal localities were ca. 870 km from each other. We recorded that in Central European Lowland the proportion of Arvicolidae in the Tawny Owl diet significantly increased, while that of Muridae decreased toward north-east. The proportion of less common rodent species (including Gliridae and Sicita betulina Pallas) in the diet also increased significantly toward NE. We did not record any trend of small mammals diversity along the analysed transect. We suggest that the change of Arvicolidae to Muridae ratio toward north-east can be caused by the replacement of mice with boreal vole species in small mammal community. Small mammal diversity in Central Europe is subject of discussion.

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Central-place foraging in an urban landscape : body mass of common voles (Microtus arvalis Pall.) caught by breeding Kestrels (Falco tinnunculus L.) is positively correlated with availability of hunting sites

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Kubacka J. , Żmihorski M. , Mirski P. , Rejt Ł.

Polish Journal of Ecology

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2010

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tom Vol. 58, nr 2

387-391

EN

In the reproduction period a male Kestrel (Falco tinnunculus) is a centralplace forager, i.e. it transports food from hunting grounds to a central location - the nest. A centralplace forager is predicted to take larger or more prey when distance to a foraging site is longer. We studied kestrels breeding in a large Central European city (population 1.7 million), whose main prey are common voles (Microtus arvalis). Kestrel nests are located in the centre and the outskirts, although common voles are scarce in the former. The aim of our study was to analyse the body mass of common voles found in pellets under kestrel nests and relate it to the availability of common vole habitats within 1 km from the nests, controlled for vole frequency in the pellets. We assumed that the greater availability of common vole habitats, the shorter the distance to a foraging site. We found that the body mass of common voles found in pellets was significantly positively correlated with the availability of their habitats, but was not affected by their frequency in pellets. Our results may indicate that, contrary to the central-place foraging rule, and irrespectively of the amount of other prey taken, the kestrels hunted smaller voles when foraging grounds were further away. This might stem from decreased selectivity caused by competition, either in the native territory (due to the high density of kestrels in the centre) or in territories of outskirt kestrels, invaded by city centre kestrels. On the other hand, due to lack of data on the body size of common voles in our study area, the results may suggest that common voles were on average smaller in the centre than in the outskirts. Although the published data do not support the second explanation, more research is needed to verify this.