Haemoparasites represent a diverse group of vector-borne parasites that infect a wide range of vertebrate hosts. In birds, haemoparasite infection rates may be associated with various ecological and life history traits, including habitat choice, colony size and migration distance. Here, we molecularly assessed the prevalence of 3 main haemoparasite genera (Plasmodium, Haemoproteus and Leucocytozoon) in 2 bird species with different habitat preferences and migratory behaviour: black-headed gulls (Chroicocephalus ridibundus) and common terns (Sterna hirundo). We found that gulls showed a much higher prevalence and diversity of Plasmodium or Haemoproteus (ca. 60% of individuals infected) than terns (zero prevalence). The prevalence of Leucocytozoon was low in both species (<3%). The differences in haemoparasite prevalences may be primarily driven by varying vector encounter rate resulting from different habitat preferences, as black-headed gulls mainly use vector-rich vegetated freshwater habitats, whereas common terns often use vector-poor coastal and brackish habitats. Since common terns migrate further than black-headed gulls, our results did not provide support for an association between haemoparasite prevalence and migratory distance. In gulls, we found a negative association between colony size and infection rates, suggestive of an ideal despotic distribution, and phylogenetic analyses of detected haemoparasite lineages provided evidence for higher host specificity in Haemoproteus than Plasmodium. Our results suggest that the preference for coastal areas and less vegetated habitats in terns may reduce haemoparasite infection rates compared to other larids, regardless of their migratory distance, emphasizing the role of ecological niches in parasite exposure.

There is increasing evidence that melanin-based plumage ornaments play a role in the sexual selection of birds, although there seems to be little consensus on the mechanisms underlying the signalling function of melanin-based plumage. The aim of this study was to assess the potential of a melanin-based plumage ornament (brown hood) to reflect components of individual quality (condition and physiological stress) in a common larid species, the Black-headed Gull Chroicocephalus ridibundus. For this purpose, we measured the size of the hood in over 500 Black-headed Gulls captured in several breeding colonies distributed across Poland. We found that hood size correlated positively with blood haemoglobin concentration, although we found no evidence for a relationship with blood glucose concentration or body mass. There was also a negative relationship between hood size and physiological stress, as assessed by leucocyte profiles (heterophil/lymphocyte ratio). We found this correlation in both sexes, suggesting that hood size may be an honest signal of individual quality in males and females, which implies a mutual mate choice in the Black-headed Gull. Finally, the relationship between hood size and blood haemoglobin concentration was primarily attributed to the parallel variation of these traits among the colonies, suggesting that Black-headed Gulls may settle in colonies in a despotic manner. As far as we are aware, our study is one of the first to show an honest signalling role of melanin-based ornaments in the gull family, Laridae. It remains to be tested whether different melanin-based plumage ornaments in gulls are developmentally and functionally integrated with each other and with carotenoid-based integument coloration.

Rapid urbanization has a great impact on avian distribution, ecology, habitat selection, and behavior. Recent avian studies indicated that individuals remain consistent in their behavioral responses to human disturbance across short periods of time. However, there is still little information about keeping consistent behaviors in distinct locations across different stages of the annual cycle. In this study, we aimed to test for long-term consistency in habitat selection with respect to urbanization in a migratory waterbird species, the Eurasian coot Fulica atra. For this purpose, we individually marked ca. 300 coots from four populations that varied in urbanization level and tracked their habitat preferences during the non-breeding season. We found that individuals from urban breeding populations selected habitats with a higher share of artificial areas during the non-breeding season, when compared to non-urban individuals. Also, a comparison of non-breeding sites selected by birds from our study populations with random sites showed that urban birds selected sites with higher urbanization level than resulting from random availability. Finally, we found a seasonal variation in habitat preferences in coots—individuals from all study populations selected more urbanized areas as the non-breeding season progressed. The results indicate that birds are able to remain consistent in habitat preferences not only at a large geographical scale, but also across different seasons. Marked between-population variation in habitat selection across the annual cycle may reflect personality differences of coots from urban and non-urban populations, and it stays in line with the personality-matching habitat choice hypothesis.

No abstract

No abstract