Intercolony variation in foraging flight characteristics of black-headed gulls Chroicocephalus ridibundus during the incubation period.

Using GPS loggers, we examined the influence of colony, sex, and bird identity on foraging flight characteristics of black-headed gulls Chroicocephalus ridibundus during the incubation period. We studied tracks of 36 individuals breeding in one urban and two rural colonies in Poland. Birds from both rural colonies performed the furthest flights (mean max distance 8-12 km, up to 27 km) foraging mainly in agricultural areas. Gulls from the urban colony performed shorter flights (mean 5 km, up to 17 km) visiting mainly urbanized areas and water bodies. We found that females performed longer flights and their flight parameters were less repeatable compared to males. Males from both rural colonies visited water bodies more frequently than females. In all colonies, males (but not females) used habitats unproportionally to their availability in the vicinity. Relatively low interindividual and relatively high intraindividual overlap in home ranges indicated considerable foraging site fidelity. Individuals specialized in the use of a particular type of habitat performed shorter foraging flights compared to individuals using diverse habitats during their foraging flights. Our results indicate diverse foraging strategies of black-headed gulls, including generalists that explore various habitats and specialists characterized by high foraging site and habitat fidelity.

Louse Flies of Charadrii and Scolopaci Shorebirds Migrating through Central Europe.

Louse flies are blood-sucking ectoparasites of birds and mammals of veterinary and medical importance. These flies damage host skin and serve as vectors for blood-associated pathogens. Little is known about their phenology, host selection, and prevalence in wild birds. Our study provided a broad-scale assessment of louse flies parasitizing Charadrii and Scolopaci shorebirds during their migration through Central Europe. We collected louse flies from 3,129 specimens in 22 species of shorebirds at a major migratory stopover site in central Poland in 2011-17. In total, 31 Ornithomya avicularia and 15 Ornithomya chloropus specimens occurred on five wader species: Common Snipe (Gallinago gallinago), Ruff (Calidris pugnax), Dunlin (Calidris alpina), Curlew Sandpiper (Calidris ferruginea), and Wood Sandpiper (Tringa glareola). Prevalences ranged from 0.23% to 4.62%. No individual birds were infested by both species of fly, and no flies were found on an additional 17 wader species. The rarer of the two flies, O. chloropus, occurred on all infested bird species, whereas O. avicularia occurred only on Common Snipe and Curlew Sandpiper. In comparison with the other four infested wader species, Common Snipe (n=1,194) was more frequently infested with O. avicularia than with O. chloropus. Our study shows that the prevalence of louse flies on shorebirds is much lower than on other avian taxa. Ecologic and evolutionary mechanisms leading to the relative rarity of louse flies on shorebirds remain to be understood.

Silver spoon effects on plumage quality in a passerine bird.

A silver spoon effect means that individuals who develop under favourable circumstances enjoy a fitness or performance advantage later in life. While there is large empirical support for silver spoon effects acting on different life-history traits in birds, such as survival and reproduction, the evidence for the carry-over effects of rearing conditions on the quality of future plumage generations is lacking. Here, we examined whether abilities of individuals to undergo extensive post-juvenile moult may depend on the quality of juvenile plumage developed during the nestling phase in a small passerine showing large individual variation in the extent of post-juvenile moult, the greenfinch (Carduelis chloris). We found that high structural quality and carotenoid chroma of juvenile feathers were positively linked to the extent of post-juvenile moult in this species, thus allowing young birds to attain more adult-like plumage. Silver spoon effects mediated by the juvenile plumage quality were also found to have other fitness-related consequences, as individuals with high-quality juvenile feathers were in better condition during their first winter. As far as we are aware, the results provide the first correlative evidence for a silver spoon effect acting on general plumage quality in birds.

Collyriclosis in Central European hirundines.

Cutaneous monostome trematode Collyriclum faba (Bremser in Schmalz 1831) is a digenetic flatworm with unknown life cycle. Here, we provide the first compelling evidence that despite low prevalence of the parasite, European hirundines are parasitized by this species. First host record for sand martin (Riparia riparia) and first European host record for barn swallow (Hirundo rustica) is provided. The birds were captured and checked in ten European and Middle Eastern countries, stretching from Ireland to Bahrain, but only samples from Central Europe (Czech Republic, Hungary and Poland) were positive for C. faba. In total, 164,582 sand martins and 100,443 barn swallows were examined, and seven and two birds had cutaneous C. faba cysts. Even though over 40% of the birds captured were juveniles, all but one infected individuals were adults, equally both males and females. The prevalence of the parasite on Central European hirundines were calculated as one in 20,641 for sand martins and one in 4,484 for barn swallows. All the infected birds were captured in close vicinity of water bodies. All the cysts were found close to the vent or on the legs. No adverse effects on its bird hosts were observed.