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National Repository of Grey Literature 2 records found  Search took 0.01 seconds. 
Temporal changes in bird communities at the landscape level in Třeboň basin
 Havelka, Jan ; Sedláček, Ondřej (advisor) ; Reif, Jiří (referee)
Population trends of birds are usually studied mainly on large national and continental scales or, on the contrary, quite locally. In an attempt to link these spatial scales, we repeated a quantitative survey of bird communities in the Třeboň Protected Area twenty years later (between 2001 and 2021). Bird counts were conducted during the breeding season on a fifty- kilometre transect (128 count points) intersecting a diverse range of habitats. We found declines in long-distance migrants and insectivorous birds compared to more stable or slightly increasing populations of resident species. Consistent with known trends, we also observed declines in populations of species tied to agricultural landscapes. Deviations from the well described trends by JPSP and PECBMS relate more to individual species characteristics. For example, we observed increases in populations of otherwise declining House Sparrow (Passer domesticus) and Field Sparrow (Passer montanus), or nationally stable Eurasian Siskin (Spinus spinus). Using detailed mapping of habitat and vegetation changes and other ecological characteristics of individual species, we have attempted to explain these general and site-specific changes in bird abundance and population trends. We were also interested in the manifestations of the generally...
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Bird Communities Along the Altitudinal Gradient on Mt. Cameroon: Perspectives from Mist Nets
 Petruf, Miroslav ; Sedláček, Ondřej (advisor) ; Lučan, Radek (referee)
in English Mt. Cameroon is a hotspot of diversity and endemism in Africa. Recent research of avian bird communities along the elevational gradient on Mt. Cameroon based on point counts has shown low-elevation plateau of species richness. At the same time, range-restricted montane populations of birds on Mt. Cameroon are unusually abundant if compared to lowland species. I analysed data on community composition, species richness and abundance of birds using an alternative quantitative method - 200 m of understory mist nets erected for three consecutive days across seven elevational plots along the forested gradient of the Mt. Cameroon. First, I looked at the technical limits of this method and confirmed the general opinion that they are better at detecting small birds below 33 g, and that they mostly detected fewer individuals after the first day and always detected fewer new species after the first day of mist-netting. Mist nets detected high proportions of ground-feeding and understory birds and low proportions of birds foraging in higher strata in the lowland forest, which has a scarce understory and a dense canopy. Mist nets recorded similar proportions of birds foraging in all forest strata in the vastly open mid-elevation forest, which has a dense herbaceous understory. They detected higher...
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