Do agricultural environments increase the reproductive success of White Stork Ciconia ciconia populations in South-Western Poland?

As populations of White Stork Ciconia ciconia have decreased at different rates in Europe, the specific environmental drivers that influence breeding success are a matter of controversy. Here we use body size, blood, and environmental data of a total of 1226 stork nestlings of different ages from a total of 363 nests in three different habitats (meadows, forest-edges, open agricultural landscapes) in S-W Poland to ask whether: 1) natural grassland environments increase the reproductive output in comparison with agricultural landscapes, 2) nestlings from agricultural landscapes differ in health status from nestlings in more natural habitats, 3) differences in environmental stress translate into respective differences in reproductive output and health status of nestlings. There was no significant difference in age corrected body mass and in the temporal increase in nestling mass between the study sites. Clutch sizes were highest and age corrected total clutch mass lowest at the meadow sites while agricultural and woodland sites did not significantly differ. Hemoglobin and red blood cell content were lowest and white blood cell and blood antioxidant concentrations were highest in the meadows indicating higher degrees of environmental stressors. These blood parameters varied strongly among study years. Our study does not confirm that agricultural landscapes are less suited for stork breeding success. We even find some indication of a better health status of nestlings in agricultural environments that might compensate smaller clutch sizes. Our data indicate that reproductive output is multifaceted. As we found some indication of a trade-off between clutch size and health status we argue that only multiple metrics of reproductive success are able to assess the long-term effect of habitat choice on fitness.

Prevalence, virulence, and antimicrobial resistance of Campylobacter jejuni and Campylobacter coli in white stork Ciconia ciconia in Poland.

The aim of this study was to investigate the role of white stork Ciconia ciconia as a potential reservoir of Campylobacter spp. Antimicrobial resistance and the presence of putative virulence genes of the isolates were also examined. A total of 398 white stork chicks sampled in Western Poland in habitats with high density of breeding were examined. Rectal swabs were collected during breeding season 2009-2012 from storks developing in a relatively pure environment (Odra meadows), in polluted areas (a copper mining-smelting complex), and in suburbs. Of the anal swabs collected, 7.6% were positive for Campylobacter among chicks (5.3% samples positive for C. jejuni and 2.3% samples positive for C. coli). Samples from polluted areas had the highest prevalence of Campylobacter (12.2%). The prevalence of resistance among C. jejuni and C. coli isolates from young storks was as follows: to ciprofloxacin (52.4%, 44.4%), and to tetracycline (19%, 77.8%). All of the analyzed isolates were susceptible to macrolides. The resistance to both classes of antibiotics was found in the 23.3% of Campylobacter spp. All Campylobacter spp. isolates had cadF gene and flaA gene responsible for adherence and motility. CdtB gene associated with toxin production was present in 88.9% of C. coli isolates and 57.1% of C. jejuni isolates. The iam marker was found more often in C. coli strains (55.6%) compared to C. jejuni isolates (42.9%). Our results confirm the prevalence of Campylobacter spp. in the white stork in natural conditions and, because it lives in open farmlands with access to marshy wetlands, the environmental sources such as water reservoirs and soil-water can be contaminated from white stork feces and the pathogens can be widely disseminated. We can thus conclude that Campylobacter spp. may easily be transmitted to waterfowl, other birds, and humans via its environmental sources and/or by immediate contact.