Maria Denisa Conete
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breeding birds, ability to adjust.
The author conducted an ornithological study in the Bascov Reservoir area (a square of 2x2 km) and observed 102 breeding species; 83 (81%) of them are certain breeding species and 19 (19%) are probable breeding species. The results of the research were cumulated with those found in the Atlas of the breeding species of Romania. By relating them with the Atlas data, we noted that 83 of the 100 breeding species cited in the Atlas were again recorded during our study. Nineteen new breeding species were identified. Among the species dependent on wetlands, mention should be made of Ixobrychus minutus, Anas platyrhynchos, Fulica atra, Gallinula chloropus, Aythya ferina, etc., with relatively large numbers of individuals. The analysis showed a relatively larger number (66) of euconstant and constant species, which confirmed the wealth of food resources in the area during the nesting period. The specific richness on the Bascov Lake is represented by 119 species, a number that is consistent with the availability of the food resources and nesting places, as well as the somewhat fluctuating presence of predators (stray dogs), and the anthropocentric disturbance (sound and chemical pollution, etc.). The yearly increase in the number of reed clusters, the expansion of the surface of the islets, the emergence of bushes and trees, the ageing of the existing trees have led to a certain yearly increase in the number of breeding individuals in 45 species. But the anthropogenic influence in the area has eventually contributed to a decrease in the number of birds, both as a number of species and as a number of individuals. The study has also shown that in the farmland bird species the number of individuals is in decline. Most of the breeding species - 75 (representing 74%) in the area under research are migratory. Eighteen breeding species (17.64%) are listed in Annex I of the Birds Directive. The presence of the key breeding species in the area under research must be considered an important argument for the real protection of the respective area. We consider that the informational stress (the persistent noise pollution) as well as chemical pollution (chemical fertilizers, pesticides, detergents, etc.) affect in a certain measure not only the success rate of bird breeding but also the normal development of their offspring, at least in those species that are sensitive to the presence of humans. Under these circumstances, there may be unfortunate consequences on the orientation of birds during migration, in spite of the fact that they showed a considerable plasticity of the avian magnetic compass.
