Pracownia Badań Ornitologicznych
original scientific papers
MIZ PAS affiliation
The Hooded Crow Corvus cornix density as a predictor of wetland bird species richness on a large geographical scale in Poland.
Kosicki J.Z., Chylarecki P.
Ecological Indicators, 38: 50–60.
Bird species richness; Conservation; Hooded Crow density; Predictive mapping; Surrogate; Spatial differences; Wetlands; Species distribution modelling
Evaluating wetland bird species richness on a national scale can be extremely hard as it is prohibitively expensive, expert knowledge of bird species determination is indispensable, and wet areas tend to be difficult to study. For these reasons we tested the usefulness of the Hooded Crow, a bird easy to detect, as a surrogate for wetland bird species richness in Poland. Its primary habitats are situated in flooded river valleys and other wet areas where it is a nest predator of many water birds. What is more important, we found a significant correlation between this raw species density and our target group (r = 0.29, p < 0.001). Therefore, we suspected that on the whole country the Hooded Crow could potentially reflect wetland bird species richness.
We analyzed factors affecting the Hooded Crow's density and wetland bird species using data from 776 1 km × 1 km study plots and a set of 22 environmental variables. Next we developed analysis where apart environmental variables we also used density of the Hooded Crow as an additional predictor of wetland bird species. Habitat and climatological predictors were aggregated using Principal Components Analyses, then related to the Fourier estimator of the Hooded Crow's density and the Jackknife estimator of wetland bird species richness by applying General Additive Models. Finally, competing models were assessed according to information – theoretic criteria.
The best-supported models for both the standardized Hooded Crow's density and wetland bird species richness covered 8 almost the same aggregated predictors. The models on wetland bird species could be further improved by including the standardized Hooded Crow density, showing the potential to use Hooded Crow as surrogate for wetland bird species richness (delta AIC = 10.5).
Both groups prefer lowland water areas surrounded by meadows, where rivers are distributed rather evenly, and where precipitation is relatively high. The greatest differences between these groups appear on areas where farmland mechanization is high. Such areas are used by Hooded Crows, but avoided by wetland birds. Besides, unlike wetland species, Hooded Crows definitely avoids the north of Poland which is covered by large dense forests interspersed with rivers. Therefore, the Hooded Crow reflects wetland species richness only in open lowland habitats, dominated by wet meadows, where the landscape is interspersed with rivers and lakes, and hydrological conditions are repeatable from year to year. The Hooded Crow cannot be used as an indicator of wetland birds on a large area of intensively used farmland or in large deciduous forest interspersed with rivers.
MIZ PAS affiliation
Effects of weather conditions, time of breeding, brood size and hatching order on Eurasian bittern nestling growth in a food-rich fishpond habitat.
Kasprzykowski Z., Polak M., Chylarecki P.
Annales Zoologici Fennici, 51: 477–487.
The development of nestlings depends on both biological and weather factors. However, their combined effect differs among bird species. In this study, the impacts of three temperature variables, precipitation, wind speed, timing of breeding, brood size and hatching order on the growth of Eurasian bittern Botaurus stellaris chicks were analysed. Measurements of 183 nestlings from 57 nests were made at fishpond complexes in eastern Poland. Relative growth rates (RGR) were calculated on the basis of tarsus length and body mass. Generalised linear mixed models showed that brood size, hatching order and precipitation were the most important factors. Nestlings in broods of two and three grew faster than those from broods of four and five. In the largest broods, the fifth-hatched chicks had lower growth rates; this also applied to the oldest chicks in all brood-size categories. Nestlings from late-season nests showed enhanced mass and tarsus growth, while heavier precipitation and strong winds depressed growth rates. The study emphasises that even among bitterns breeding in food-rich habitats like fishponds, the chicks in largest broods run the risk of lower growth rates.
MIZ PAS affiliation
The effects of forest patch size and ownership structure on tree stand characteristics in a highly deforested landscape of Central Poland
Żmihorski M.,Chylarecki P., Rejt Ł., Mazgajski T.D.
European Journal of Forest Research, 129: 393-400.