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Long-term changes in the numbers of waterbirds at an important European wintering site

100%
Marchowski D., Lawicki L., Guentzel S., Kaliciuk J., Kajzer Z.
Acta Biologica
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2018
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tom 25
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A multi-isotope (delta2H, delta13C, delta15N) approach to establishing migratory connectivity in Palearctic-Afrotropical migrants: An example using Wood Warblers Phylloscopus sibilatrix

75%
Hobson K. A., Van Wilgenburg S. L., Wesolowski T., Maziarz M., Bijlsma R. G., Grendelmeier A., Mallord J. W.
Acta Ornithologica
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2014
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tom 49
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nr 1
Wood Warblers Phylloscopus sibilatrix have declined considerably throughout most of their north and western breeding range in Europe but the causes of this decline are unknown. Declines may be related to factors on the breeding grounds, stopover sites and/or wintering grounds. We used multi-isotope (δ²H, δ¹³C, δ¹⁵N) measurements of winter-grown feathers of 314 individuals breeding in the Białowieża Forest (E Poland) to infer where they wintered in sub Saharan Africa over a 4-year period from 2009-2012. We used both aspatial and spatially specific assignment techniques involving a previously developed clustering algorithm related to long-term patterns of precipitation (δ²H) and theoretical plant-based isoscapes (δ¹³C, δ¹⁵N) for Africa. We determined that our breeding population was consistently assigned to the forested region of the Congo basin. Males were more depleted in ¹³C and ²H and more enriched in ¹⁵N than females suggesting potential sexual habitat segregation on the wintering grounds. We then similarly examined less extensive samples from Wood Warblers breeding in England, Netherlands, Germany, Switzerland and Karelia (NW Russia), and found a similar assignment to the Congo basin. For all sites, males were isotopically distinct from females suggesting sex-specific habitat segregation on the wintering grounds. Our geospatial assignment model now provides a protocol for testing the hypothesis that declining populations winter more in heavily fragmented forests of west Africa compared to the Congo basin. We encourage this approach for the investigation of migratory connectivity in other sub Saharan Afrotropical migrants.
3

Habitat structure of temporary settlement areas of young Saker Falcon Falco cherrug females during movements in Europe

51%
Nemcek V., Uhrin M., Chavko J., Deutschova L., Maderic B., Noga M.
Acta Ornithologica
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2016
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tom 51
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nr 1
During 2008-2011, nine juvenile Saker Falcon Falco cherrug females were tagged with satellite transmitters in Slovakia. Satellite telemetry provided new insights into the juveniles' movements. In this study we present the use of temporary settlement areas (TSAs) during the movement of the tracked juveniles. We characterized natal areas (NAs, the first TSA in the life cycle of juvenile, restricted to the nest) and TSAs as areas where the distance between the all- night perches did not exceed ten kilometres and where a particular bird spent at least five consecutive days. In these areas 3 types of polygons were identified in relationship to the area of use — a home range (95% kernel polygons), a core area (50% kernel polygons) and an overall used area (100% minimum convex polygons). The overall used areas were highly variable and probably influenced by exploratory flights, when sakers fly out of their home ranges and come back at night. Habitat preference was then analysed in the TSAs for a better understand of juvenile habitat requirements. For habitat preference a CORINE raster image (version 13/2006) with a resolution of 100 x 100 m was used. In the TSAs 14 habitat categories were recorded, but for statistical analysis only 8 habitat categories were used. Conservation status of the NAs and TSAs was also described. Arable land represented the dominant habitat category in the TSAs (mean 67.64% for overall used areas, and 80.94% for core areas). A significant difference was found in the habitat structure of the overall used areas, the home ranges and the core areas. All of the tracked Saker Falcons preferred arable land, while avoiding two habitat categories — forests and scrub and/or herbaceous vegetation associations. The number of days spent in the TSAs (9-139 days, mean = 46.7 days) and in the NAs (36-134 days, mean = 62.3 days) varied by different individuals. Most of the NAs and TSAs are at least partially covered by protected areas, only four areas had no conservation status.
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