Contrasting haemoparasite prevalence in larid species with divergent ecological niches and migration patterns.

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.

Low Occurrence of Acinetobacter baumannii in Gulls and Songbirds.

Acinetobacter baumannii is a worldwide occurring nosocomial pathogen, the natural habitats of which remain to be defined. Recently, white stork nestlings have been described as a recurring source of A. baumannii. Here, we challenged the hypothesis of a general preference of A. baumannii for avian hosts. Taking advantage of campaigns to ring free-living birds, we collected cloacal swab samples from 741 black-headed gulls (Chroicocephalus ridibundus) in Poland, tracheal and cloacal swabs from 285 songbirds in Poland as well as tracheal swabs from 25 songbirds in Slovenia and screened those for the growth of A. baumannii on CHROMagarTM Acinetobacter. Of the 1,051 samples collected only two yielded A. baumannii isolates. Each carried one variant of the bla OXA-51-like gene, i.e. OXA-71 and OXA-208, which have been described previously in clinical isolates of A. baumannii. In conclusion, our data do not support a general preference of A. baumannii for avian hosts.Acinetobacter baumannii is a worldwide occurring nosocomial pathogen, the natural habitats of which remain to be defined. Recently, white stork nestlings have been described as a recurring source of A. baumannii. Here, we challenged the hypothesis of a general preference of A. baumannii for avian hosts. Taking advantage of campaigns to ring free-living birds, we collected cloacal swab samples from 741 black-headed gulls (Chroicocephalus ridibundus) in Poland, tracheal and cloacal swabs from 285 songbirds in Poland as well as tracheal swabs from 25 songbirds in Slovenia and screened those for the growth of A. baumannii on CHROMagarTM Acinetobacter. Of the 1,051 samples collected only two yielded A. baumannii isolates. Each carried one variant of the bla OXA-51-like gene, i.e. OXA-71 and OXA-208, which have been described previously in clinical isolates of A. baumannii. In conclusion, our data do not support a general preference of A. baumannii for avian hosts.