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2 Polish Journal of Ecology

2 2008

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The potential role of nests of Black-billed Magpie Pica pica L. in accumulation and dispersal of seeds in agricultural landscape

Czarnecka J., Kitowski I.

Polish Journal of Ecology

2008

Vol. 56, nr 4

673-682

The study aimed to describe the seed pool accumulated in the nest material of Magpie Pica pica, and to determine the importance of this mechanism of seed dispersal for such ecological processes as colonization of new habitats and expansion of alien plants. The seedling germination and seed extraction methods were used to determine seed abundance in the soil layer, the inner layer, and in the lining of 9 nests collected in three types of agricultural landscape: the first with domination of arable fields; the second with similar shares of arable fields and other landscape elements such as meadows of different types, shrubs, tree clumps and rushes; and the third with domination of lowland hay meadows. In all the nests, considerable numbers of diaspores were found (from 26 to 371 seeds per nest, belonging to more than 80 taxa). The main plant groups found in the nests are species connected with field roads, weeds and ruderal species, but also meadow and brushwood species were found there. The soil was gathered by birds from habitats with low vegetation cover and large areas of bare soil. Although the structure of seed pool of nests suggests that soil was mainly collected in the close vicinity of the nests. future location, this mechanism of seed dispersal can probably be involved in long distance dispersal. Seeds of two rare kenophytes: Erucastrum gallicum (Willd.) O. E. Schulz and Diplotaxis tenuifolia (L.) DC were found in the material of nests localized more than 100 m away from their closest populations. It can be assumed that this mechanism of seed dispersal can play a potential role in the expansion of alien plants and colonisation of new habitats.

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

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

Polish Journal of Ecology

2008

Vol. 56, nr 3

521-526

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.