Explore the vast range of titles available.

Food wastes are among the factors with the greatest effects on animal populations. The white stork is among bird species that clearly profit from feeding at landfills, at least in Western Europe and North Africa. However, the rate and the consequences of this feeding are still unknown in the Central-Eastern European population, which differs from the western population not only in terms of migration routes but also in the greater availability of suitable natural breeding habitats due to less intensified agriculture. The aim of the study was to describe the use of landfills and its consequences in terms of probability of nest occupation and breeding effects in different regions of Poland. Although the most important factors influencing nest-site selection and breeding effect are still habitat quality and weather conditions, distance to landfills is important in selection of nest sites. White storks use landfills most intensively late in the breeding season, independently of the density of breeding pairs. The results suggest that the use of landfills is not currently essential in the Central-Eastern European population of the white stork, does not affect breeding effect, and may be more frequent in non-breeders. However, this phenomenon is still developing and requires continuous monitoring.

Major histocompatibility complex (MHC) genes code for key proteins of the adaptive immune system, which present antigens from intra-cellular (MHC class I) and extra-cellular (MHC class II) pathogens. Because of their unprecedented diversity, MHC genes have long been an object of scientific interest, but due to methodological difficulties in genotyping of duplicated loci, our knowledge on the evolution of the MHC across different vertebrate lineages is still limited. Here, we compared the evolution of MHC class I and class II genes in three sister clades of common passerine birds, finches (Fringillinae and Carduelinae) and buntings (Emberizidae) using a uniform methodological (genotyping and data processing) approach and uniform sample sizes. Our analyses revealed contrasting evolutionary trajectories of the two MHC classes. We found a stronger signature of pervasive positive selection and higher allele diversity (allele numbers) at the MHC class I than class II. In contrast, MHC class II genes showed greater allele divergence (in terms of nucleotide diversity) and a much stronger recombination (gene conversion) signal. Gene copy numbers at both MHC class I and class II evolved via fluctuating selection and drift (Brownian Motion evolution), but the evolutionary rate was higher at class I. Our study constitutes one of few existing examples, where evolution of MHC class I and class II genes was directly compared using a multi-species approach. We recommend that re-focusing MHC research from single-species and single-class approaches towards multi-species analyses of both MHC classes can substantially increase our understanding MHC evolution in a broad phylogenetic context.

The choice of colony size may have profound consequences for individual fitness in colonially breeding birds, but at the same time it may require certain behavioural adaptations. Here, we aimed to examine behavioural divergence of common terns Sterna hirundo nesting in colonies of different size. For this purpose, we promoted establishment of small (<35 pairs) and large (>100 pairs) tern colonies under uniform ecological and environmental conditions by providing attractive patches of nesting substrate (floating rafts) at a single site. We combined video recording and GPS-tracking to assess communal and individual defence initiation rate, intra-specific aggression rate, and foraging flight characteristics. We found that birds from larger colonies more frequently engaged in communal defence and they performed longer foraging flights, while terns from smaller colonies more frequently showed individual defence behaviours. Also, intra-specific aggression rate was higher in smaller colonies, but this effect was primarily attributed to a higher proportion of edge breeding pairs, which were more aggressive. Our results suggest that various colony sizes may be associated with different behavioural syndromes, which comprise of diverse personality traits, such as social responsiveness, social tolerance, or propensity for aggression. It remains to be tested whether these behavioural differences reflect processes of phenotypic sorting among colonies of different size or whether they are a result of behavioural plasticity under different social contexts.

Background Nesting in large aggregations provides several important advantages for colonially breeding birds. However, it also imposes certain costs, associated with facilitated pathogen transmission and social stress. The cost-benefit ratio is not similar for all the birds in a colony and it might be mediated by nest density. To investigate the influence of nest density on cell-mediated immune function and on physiological condition of nestlings, we arranged a cross-fostering experiment in three breeding colonies of black-headed gulls Chroicocephalus ridibundus . First, we exchanged eggs between plots of high and low nest density. Afterwards, we performed phytohaemagglutinin (PHA) skin test and we measured blood haemoglobin concentration in nearly 350 nestlings from experimental (exchanged) and control (non-exchanged) groups. Results We found that PHA response was lowest in high nest density control group, indicating that depressed immune function of offspring, likely caused by social stress, can be considered as a cost of colonial breeding. Contrastingly, body condition of nestlings was the poorest in low density control group. Conclusion Nestlings hatched and raised in high nest density plots did not have higher blood haemoglobin concentration in comparison to other study groups. Furthermore, they were affected with depressed cell mediated immune function, which is possibly driven by combined maternal (corticosteroid hormones deposited in yolk) and environmental (elevated social stress) effects. These results indicate that breeders from high nest densities do not benefit by rising offspring in better quality, in terms of immune function and body condition, although, in the light of previous studies, high nest densities are occupied by birds of higher individual quality, than low density areas. Our study provides a novel insight into the mechanisms of density-dependence that govern fitness of colonially nesting birds.

Great Egret Ardea alba is one of few Western Palearctic species that underwent a rapid range expansion in the recent decades. Originally breeding in central and eastern Europe, the species has spread in northern (up to the Baltic coast) and western (up to the western France) directions and established viable breeding populations throughout almost entire continent. We monitored one of the first Great Egrets colonies established in Poland to infer migratory patterns and survival rates directly after range expansion. For this purpose, we collected resightings from over 200 Great Egret chicks marked between 2002–2017 in central Poland. Direction of migration was non-random, as birds moved almost exclusively into the western direction. Wintering grounds were located mainly in the western Europe (Germany to France) within 800–950 km from the breeding colony. First-year birds migrated farther than adults. We found some, although relatively weak, support for age-dependent survival of Great Egrets and under the best-fitted capture-recapture model, the estimated annual survival rate of adults was nearly twice higher than for first-year birds ( φ ad  = 0.85 ± 0.05 vs. φ fy  = 0.48 ± 0.15). Annual survival rate under the constant model (no age-related variation) was estimated at φ  = 0.81 ± 0.05. Our results suggest that Great Egrets rapidly adapted to novel ecological and environmental conditions during range expansion. We suggest that high survival rate of birds from central Poland and their western direction of migration may facilitate further colonization processes in western Europe.

Bird feeders are known to be a transfer site for many important bird pathogens, such as zoonotic Salmonella spp., known to be widespread among wild birds in Poland. The aim of the study was to investigate (1) whether feeders can be a source of Salmonella spp., (2) whether the risk is the same for feeders located in cities and rural areas and (3) whether there is a different level of contamination with Salmonella spp. between old and new feeders. Data were collected in the period 12 January–28 February 2018 in four cities in Poland and nearby rural areas. In total, 204 feeders were sampled. The samples from feeders were taken after a 2-week period of feeding birds. Material for analysis consisted of the remains of food and feces. We did not find the presence of Salmonella spp. in any of the tested samples collected from bird feeders. Therefore, the estimated value of the 95% confidence interval for the binary data was 0.000–0.018. Reasons for the isolation of Salmonella spp. from feeders not being successful lie in the low intensity of bacterial shedding by infected wild birds and low survival of bacteria in the environment in bird feces—which are still not well studied.

The number of White Storks (Ciconia ciconia) has been decreasing in many parts of Europe at least since the middle of the 20th century. Intensification of agriculture and continuous conversion of natural habitats, such as wetlands, into agricultural landscapes have been recognized as the most important determinants of dramatic reductions in population sizes of this species. For this reason, providing quantitative estimates of habitat requirements may allow us to identify the key biota which should be prioritized for conservation. The aim of this study was to investigate White Storks' habitat selection in a mosaic agricultural landscape in central Poland. We found that territories associated with large river valleys were highly preferred by first-arriving storks. We also recorded lower intensity of brood reduction and higher reproductive success of storks breeding in such territories. Thus, it seems likely that location of nests close to river valleys provided easy access to rich food resources associated with wetlands. In fact, distance to nearest wetland was the second strongest predictor of nest-site selection in the studied population. We also demonstrated that pairs nesting in the territories with a high proportion of wetlands showed lower levels of brood reduction in comparison to pairs having poorer access to wet habitat patches. Finally, we found that although early arriving storks avoided settling in an urbanized landscape, they selected nesting sites located close to buildings. The results of this study confirmed high importance of wet grasslands for the core central European population of White Storks.

Domestic and wild mammals, domestic birds and particularly wild birds are considered to be reservoirs of many species of Enterobacteriaceae , and also important human enteric pathogens, e.g., the bacteria of the genus Campylobacter that occur in their digestive tracts. These species may be vectors of antimicrobial resistance dissemination in the environment, because they may have contact with an environment contaminated with antibiotics. Bird feeders have been suggested as potential dispersal centres between wild wintering birds whose feeding is supported by humans. Therefore, we checked for the presence of Campylobacter bacteria among great tits Parus major , the most common bird species on bird feeders in Poland. Samples ( n  = 787 cloacal swabs) were collected in urban and rural areas of Poland. Bacterial species were identified using multiplex PCR, and 23 (2.9%) positive tests for Campylobacter spp. were found; in ten samples, C. jejuni was detected. The odds ratio of Campylobacter infection in rural birds was over 2.5 times higher than urban birds. Ten samples with C. jejuni were tested for antibiotic resistance, and all were sensitive to azithromycin, erythromycin and gentamycin, while six isolates were resistant to tetracycline, and five were resistant to ciprofloxacin. Four Campylobacter isolates were resistant to both these antibiotics.

Moult of feathers entails considerable physiological and energetic costs to an avian organism. Even under favourable feeding conditions, endogenous body stores and energy reserves of moulting birds are usually severely depleted. Thus, most species of birds separate moult from other energy-demanding activities, such as migration or reproduction. Common snipe Gallinago gallinago is an exception, as during the first autumn migration many young snipe initiate the post-juvenile moult, which includes replacement of body feathers, lesser and median wing coverts, tertials, and rectrices. Here, we evaluated moult-related changes in blood plasma biochemistry of the common snipe during a period of serious trade-off in energy allocation between moult and migration. For this purpose, concentrations of basic metabolites in plasma were evaluated in more than 500 young snipe migrating through Central Europe. We found significant changes in the plasma concentrations of total protein, triglyceride and glucose over the course of moult, while the concentrations of uric acid and albumin did not change. Total protein concentration increased significantly in the initial stage of moult, probably as a result of increased production of keratin, but it decreased to the pre-moult level at the advanced stage of moult. Plasma triglyceride concentration decreased during the period of tertial and rectrice moult, which reflected depletion of endogenous fat reserves. By contrast, glucose concentration increased steadily during the course of moult, which could be caused by increased catabolism of triglycerides (via gluconeogenesis) or, alternatively, due to increased glucocorticoids as a stress response. Our results suggest that physiological changes associated with moult may be considered important determinants of the low pace of migration typical of the common snipe.

Early arrival at breeding grounds have important fitness consequences for migratory birds, both at individual and population level. The aim of this study was to investigate how the timing of arrival at the breeding territories affects the spatial patterns of reproductive success within a population of white storks ( Ciconia ciconia ). Data were gathered annually for ca. 200 pairs of storks breeding in central Poland between 1994 and 2011. Geostatistical analysis of data indicated that in years of delayed arrival of the population (measured by the first quartile arrival date), the reproductive output of storks was negatively autocorrelated, which indicated that there was a tendency for pairs of high breeding success to neighbour with pairs of low success. By contrast, in years when first storks returned in early dates to the breeding grounds, their reproductive success did not show any kind of spatial autocorrelation. These results suggest that delayed return of the first-arriving storks of the population may increase intensity of intra-specific competition to the level at which high-quality breeding pairs monopolize most of available resources at the expense of neighbouring low-quality pairs, which have lower reproductive success as a consequence. Such hypothesis was further supported with the analysis of nesting densities, showing that the late-arriving breeding pairs incurred greater fitness costs (or derived lower fitness benefits) while breeding in high densities comparatively to the early-arriving conspecifics.