Large numbers of Mallard Anas platyrhynchos (max. 10,490 ind.), Black-headed Gull Chroicocephalus ridibundus (max. 3,430 ind.) and Great Cormorant Phalacrocorax carbo (max. 1,449 ind.) were recorded on the Goczałkowice Reservoir, Poland (2,754 ha). Most of the waterbirds occurred in the backwater of this reservoir. The amount of phosphorus and nitrogen loaded by the most numerous waterbirds into Goczałkowice Reservoir was estimated at 958 kg and 2,621 kg, respectively in 2011 and 1,043 kg and 2,793 kg, respectively in 2012. In 2011 and 2012, the waterbirds introduced a considerable amount of phosphorus, nitrogen and a large number of coliforms into the backwater of the reservoir. The concentration of different forms of phosphorus and nitrogen, chlorophyll-a and bacteria coli in the water was not greater at the site of birds’ concentration (except dissolved organic nitrogen). The concentration of nitrates in the water at the site near the breeding colony of gulls in comparison with the reference site was not different. The amounts of P-tot and N-tot in the sediment were similar at the site affected by waterbirds and at the reference site. The dynamics of water masses was not the reason for the lack of differences between the studied sites.

Grey Herons foraged in a high number only in one of three preferred foraging areas in the Dobczyce Reservoir, S. Poland: (1) the backwater area at the main tributary inlet (MTI), (2) the shore of the near-dam pool (NDP), and (3) shallow lateral bay (SLB). Median value of the fraction of herons foraging in MTI was 64% of all counted in the reservoir in 2001-2002 despite the smallest fish density there (2 times smaller than in NDP, and by one order of magnitude than in SLB). Roach (Rutilus rutilus) was the most abundant both in the heron diet (13 species) and in littoral fish communities (8 species). Total length of prey ranged within 4.2-26.5 cm. The individual size range of littoral fish was similar (4.6-31.5 cm). However, the size distributions in three foraging areas and in heron diet were different. Fish longer than the median total length of heron prey, i.e. ≥8 cm in total length constituted 51.9% of heron diet, 34.7% of the fish community in MTI, 8.5% in the psammolittoral of NDP, and only 5...

Sexual size dimorphism is common in many bird species. It can lead to sex-specific differences in foraging ability. The Whiskered Tern (Chlidonias hybrida) exhibits sexual size dimorphism. Sex-specific differences in the foraging behaviour of Whiskered Terns were investigated in carp ponds during the breeding season. Foraging behaviour was different between the sexes. Males foraged mainly by shallow plunge diving into the water, while females foraged mainly by picking prey from plants and the water surface. We attributed these differences to sexual size dimorphism, as males are significantly larger than females. The foraging success of vertebrate prey capture by Whiskered Terns was high (male average = 61%, female average = 65%), and not significantly different between sexes. Males had more aggressive encounters than females. Generally, we did not find correlations between the rate of main foraging techniques of male and female Whiskered Terns and weather conditions (cloud cover and wind speed). This was probably due to the high prey availability in carp ponds.

We studied the differences between spring and winter sites of Hazel Grouse Tetrastes bonasia in a managed, temperate forest in the Beskid Mountains (Western Carpathians, Poland). The study of seasonal requirements of this species in this type of habitat was innovatory. Spring territories must provide birds with appropriate conditions for breeding and winter ones must give good habitat for wintering. The environmental variables of spring and winter sites were collected in three layers in a 100 m radius from the place of recording of the Hazel Grouse: canopy, understory and undergrowth. According to our study, the proportion of deciduous trees was greater in spring territories in comparison to winter territories in all studied layers. Conversely, greater species richness in the undergrowth and understory in spring sites of Hazel Grouse was found in comparison to winter sites. Moreover, a greater proportion of birch, poplar, willow, wild cherry and bird cherry were found in the spring sites of Hazel Grouse in comparison to winter sites. Generalized Linear Model models showed that the occurrence of overgrown clearings, clearfellings with deadwood and higher richness of grass and herbs and their cover in the forest were important habitat factors for Hazel Grouse in both spring and winter sites. Sites of Hazel Grouse were strongly affected by the proportions of beech, sycamore, fir, spruce and larch in the canopy layer in both seasons. Moreover, a greater proportion of tree species producing nuts, drupes or winged seeds was important in both spring and winter sites. Bush cover was important for winter sites of the Hazel Grouse. Food resources, mainly in winter sites are important factors for habitat selection. Summarizing, we found habitat differences between spring territory and winter sites of Hazel Grouse. In both seasons, higher habitat heterogeneity was an important factor for occurrence of this species. Jahreszeitliche Änderungen in den Habitatansprüchen von HaselhühnernTetrastes bonasiain bewirtschafteten Bergwäldern (Westkarpaten) Wir untersuchten Unterschiede zwischen den Frühjahr- und Wintervorkommen von Haselhühnern Tetrastes bonasia in einem Wirtschaftswald der gemäßigten Zone in den Beskiden (Westkarpaten, Polen). Eine solche Studie der jahreszeitlichen Bedürfnisse der Art in diesem Lebensraumtyp war etwas völlig Neues. Im Frühjahr müssen die Reviere den Vögeln geeignete Bedingungen für die Brut bieten, im Winter ein entsprechendes Überwinterungshabitat. Auf drei Ebenen bestimmten wir die Umweltvariablen von Frühjahrs- und Winterrevieren in einem Radius vom 100 m um den jeweiligen Beobachtungsort von Haselhühnern: Kronendach, Unterholz und Unterwuchs. Unserer Studie zufolge war auf allen Ebenen der Anteil an Laubbäumen in den Frühjahrsrevieren im Vergleich größer als in den Winterrevieren. Umgekehrt war in den Frühjahrsgebieten der Haselhühner eine höhere Artenvielfalt in Unterholz und Unterwuchs zu finden als in den Wintergebieten. Außerdem gab es in den Frühjahrsgebieten im Vergleich zu den Wintergebieten der Haselhühner einen größeren Anteil an Birke, Pappel, Weide, Vogelkirsche und Traubenkirsche. Generalisierte Lineare Modelle (GLM) zeigten, dass das Vorkommen bewachsener Lichtungen, von Rodungsflächen mit Totholz und eine höhere Vielfalt von Gräsern und Kräutern sowie der Grad der Bodenbedeckung im Wald sowohl bei den Frühjahrs- als auch bei den Wintergebieten wichtige Lebensraumfaktoren für Haselhühner darstellten. Von Haselhühnern genutzte Gebiete wurden zu beiden Jahreszeiten stark vom Anteil an Buche, Sykomore, Tanne, Fichte und Lärche am Kronendach beeinflusst. Außerdem war sowohl für die Frühjahrs- als auch für die Wintergebiete ein größerer Anteil an Nüsse, Steinfrüchte oder Flügelsamen produzierender Baumarten von Bedeutung. Die Bedeckung mit Gebüsch war wichtig für Überwinterungsgebiete der Haselhühner. Nahrungsquellen waren hauptsächlich in den Wintergebieten wichtige Faktoren bei der Habitatwahl. Insgesamt stellten wir Lebensraumunterschiede zwischen Frühjahrsrevieren und Überwinterungsgebieten der Haselhühner fest. Zu beiden Jahreszeiten war eine höhere Lebensraumheterogenität ein wichtiger Faktor für das Vorkommen dieser Vogelart.

We studied the variability of physico-chemical parameters in water, and heavy metal contents in water and sediment over time and along the Carpathian Biała Tarnowska River (southern Poland) and related them to catchment geology, human impact and the effect of barriers as a side aspect. The river water was well oxygenated, had pH 7.7–9.5 and was characterised by low and average flow. Temperature, pH and dissolved oxygen did not change significantly, while the contents of major ions, NO₃⁻, NH₄⁺, Mn and Fe increased gradually along the river. The major ion contents were negatively, and nitrate, Mn, and Fe positively, correlated with the flow. We recognise correlations between nitrate, Fe and Mn to be good indicators of soil erosion processes in the catchment. River sediment was unpolluted by most of the studied metals (slightly polluted by Ni and Cd). The differences in the values of some parameters (pH and NH₄⁺, PO₄³⁻, HCO₃⁻, Mn, Cd and Pb concentrations) in the water, and heavy metals in the sediment upstream and downstream of some of the barriers were determined. Spatiotemporal changes in the values of studied parameters and the results of statistical calculation indicate the impact of human activity in the catchment basin (land use, wastewater) on the water chemistry.