No abstract

Biometrics, plumage and bare‐part colour of 87 Great Bitterns Botaurus stellaris from the UK, France, Italy, Poland and Belarus, of known sex (sexed by behaviour, DNA or dissection), were analysed to provide reliable sexing and ageing criteria for this little‐known species, and to investigate geographical variation in biometrics. Four parameters were analysed: bill length, tarsus, wing length and body weight. We found little (though significant) geographical variation across Europe, but this was not clinal and we cannot exclude variation in measurement technique among observers. Males were significantly larger than females for all biometric parameters: a discriminant function based on these parameters was able to sex correctly all individuals. Body weight varied with season, especially for males. During the breeding period, lore colour was also a reliable sex‐criterion. Ageing proved more difficult and required a combination of iris colour (which darkens with age) and flight‐feather moult. From this, the largest sample size of known‐age Great Bitterns, we conclude that most previously published criteria for age determination of this species were wrong.

Sex ratio is an indicator of population health as unexpected biases may indicate potential threats. We studied nestling sex ratio in Black Stork Ciconia nigra populations in order to check potential biases and differences along east-west and north-south gradient across its distribution range in Europe. We also studied variation between years, and checked potential correlations with weather variables. The overall sex ratio of nestlings in Europe was nearly equal with a non-significant deficiency (47.1 %) of males, the larger sex. Although yearly fluctuations in sex ratio were detected, no significant effect of the year alone was found, only simultaneously with population and brood size. There was a tendency to have a higher proportion of female nestlings in larger broods, but the pattern was probably scattered by the effect of reduction of largest broods. Compared to Western and Eastern Europe, a significant deficiency of male nestlings was found in Central Europe (Poland), whereas no differences were found along the north-south gradient. We did not find any effect of temperature, but rainfall during the incubation period was negatively correlated with the proportion of male nestlings in Central (Poland) and Western Europe (France) whereas in North-Eastern Europe (Latvia) the same effect of the precipitation in pre-breeding period was found.

We report on the assessment of the level of genetic diversity of the capercaillie in Belarus. This species of birds is a valuable biological resource, and also acts as a natural indicator for the state of large forests and the degree of their disturbance by human activities. Two subspecies of the capercaillie —Tetrao urogallus major (C. L. Brehm, 1831) and Tetrao urogallus pleskei (Stegmann, 1926) have been described for Belarus. The first domain of the mitochondrial DNA control region was used as the molecular marker for the study. An additional assessment of the level of genetic diversity of the capercaillie was carried out by calculating the effective size of its population (Ne) in Belarus. We found that the absence of subspecific structure is characteristic for all samples of the capercaillie from Belarus. The data on the intraspecific structure and genetic diversity of the capercaillie from Belarus allows us to considerits population in the central and eastern parts of the country as stable and sustainable. This can be explained by its inclusion in the general phylogeographic structure of birds of the boreal lineage. The low values of the effective population size for the partially isolated capercaillie population from the western part of the country indicate the need for increased attention and further monitoring of that population.

The Common Quail (Coturnix coturnix) is a common bird species and an object of amateur hunting in Belarus. However, insufficient attention is paid to its study in our country. In this work, the occurrence of the Common Quail in all zoogeographic provinces of Belarus was calculated on the basis of data from the counts of the species. According to the results, the occurrence decreases from south to north. As a result of the analysis of the Common Quail population density data obtained from literary sources and collected in the current study in various regions of Belarus and Ukraine, it was found that the population density of the species in the agrocenoses of Ukraine is slightly higher than in Belarus.