Seasonal changes in the preen wax composition of the Herring gull Larus argentatus

Abstract

The preen gland produces oily secretion, which smeared onto a bird’s plumage improves its maintenance. The main components of the secretion are waxes, and its composition often changes during the year. The aim of this study was to determine the differences in the chemical composition of preen waxes in adult herring gulls Larus argentatus, captured in Poland in winter and in the breeding season. Preen gland secretions of herring gulls consist of monoester waxes, composed of about 29 saturated C7–C16 fatty acids and about 51 saturated C11–C20 alcohols. Unbranched-octanoic acid and n-hexadecanol dominated fatty acid and alcohol fractions, respectively, but 2-methyl-branched compounds were numerous in all individuals. The chemical compositions of fatty acids and alcohols differ between winter and the breeding season. In breeding gulls, 2-monomethyl-branched fatty acids were lower in content or could not be found, contrary to herring gulls in winter, where 2-monomethyl-substituted fatty acids were the second most abundant among all the fatty acids. Breeding gulls had also a higher content of n-octanoic acid and n-hexadecanol and a lower content of 2,6- and 2,8-dimethyl-substituted fatty acids than individuals caught during the winter. Differences in fatty acid composition were greater in breeding males, which incubate more often at night than breeding females. Hence, chemical changes in the preen wax composition in males may have evolved as additional nocturnal protection against mammalian predators which use olfaction to detect their prey and which are more active at night; however, this needs to be tested. Olfactory-based mate recognition in the colony also cannot be excluded at this stage of experimentation.

Preservation potential of keratin in deep time

“…However, neither feather sample produced ToF-SIMS spectra that in detail mimic the keratin spectrum, indicating that other molecular components may also be contributing to the spectra. This difference can be explained for the control feather in part by the presence on the feather surface of not only keratin but also of preen waxes, which are used by birds to protect their feathers from environmental influences [52–54]. These waxes are identified in the negative ion spectra as monoester molecular ions in the mass range m/z 290–460 and diester molecular ions at m/z 680–800 (S3 Fig), corresponding to the main components of bird feather preen waxes [52].…”

Preen oil chemical composition encodes individuality, seasonal variation and kinship in black kites Milvus migrans

“…We found that preen oil composition differs between sexes only in the non-breeding season, with males having higher abundance of one sterol and of a few ketonic compounds compared to females. In several bird species, preen oil composition varies with sex in the breeding season (Whittaker et al 2010, Leclaire et al 2011, Amo et al 2012, Jacob et al 2014, Fischer et al 2017. In many vertebrates, sex-differences in chemical profiles are mediated by steroid hormones (Wyatt 2014), for which sex variations are often higher during the breeding season (Wingfield et al 1990).…”

Impact of brood parasitism and predation on nest survival of the fan‐tailed gerygone in New Caledonia

“…Thus, gerygones might also prevent predation by rodents due to lack of odour cues. This has been observed in other bird species that are able to reduce their own smell by changing the composition of preen wax during the breeding season (Kolattukudy et al , Reneerkens et al , Soini et al , Fischer et al ). However, it is also possible that fan‐tailed gerygone already had a naturally low vulnerability to predation by rats, for example due to low odour production or little accessible nest locations, even if these placements are conspicuous (Dennison et al , Noske ).…”