Molecular Evidence for Gender Differences in the Migratory Behaviour of a Small Seabird

Abstract

Molecular sexing revealed an unexpectedly strong female bias in the sex ratio of pre-breeding European Storm Petrels (Hydrobates pelagicus), attracted to playback of conspecific calls during their northwards migration past SW Europe. This bias was consistent across seven years, ranging from 80.8% to 89.7% female (mean annual sex ratio ± SD = 85.5% female ±4.1%). The sex ratio did not differ significantly from unity (i.e., 50% female) among (i) Storm Petrel chicks at a breeding colony in NW France, (ii) adults found dead on beaches in Southern Portugal, (iii) breeding birds attending nest burrows in the UK, captured by hand, and (iv) adults captured near a breeding colony in the UK using copies of the same sound recordings as used in Southern Europe, indicating that females are not inherently more strongly attracted to playback calls than males. A morphological discriminant function analysis failed to provide a good separation of the sexes, showing the importance of molecular sexing for this species. We found no sex difference in the seasonal or nocturnal timing of migration past Southern Europe, but there was a significant tendency for birds to be caught in sex-specific aggregations. The preponderance of females captured in Southern Europe suggests that the sexes may differ in migration route or in their colony-prospecting behaviour during migration, at sites far away from their natal colonies. Such differences in migration behaviour between males and females are poorly understood but have implications for the vulnerability of seabirds to pollution and environmental change at sea during the non-breeding season.

Birds of a feather moult together: Differences in moulting distribution of four species of storm-petrels

“…Additionally, δ 18 O values differ over a latitudinal gradient with δ 18 O being considerably lower closer to the polar regions than the Equator and tropical zones. ESP differs in migratory behaviour between sexes [ 97 ], and shows sexual dimorphism for several body measurements but not tarsus length [ 90 ]. WSP females are slightly larger than males [ 98 ], with wings being approximately 2.8% longer in females than males [ 91 ].…”

Insights to the functional relationships of Māori harvest practices: Customary use of a burrowing seabird

“…We included both male and female birds and assumed the sex ratio of young to be equal as is the norm in procellariiform seabirds (Genovart et al , Lawrence et al , Medeiros et al ). We assumed the eggs laid produce fledglings according to annual, island‐specific, breeding success rates estimated for both modeled populations by Jones et al ( b ) using logistic exposure modeling of burrow survey data from 2006 to 2010.…”

“…Although there is likely to be variation in individuals' probability of transition to breeding with age, investigations of the effects of simplifying age structure in demographic models have demonstrated that this has little effect on estimates of population growth rates or on perturbation analyses (Heppell et al 2000a, Hunter et al 2000. We included both male and female birds and assumed the sex ratio of young to be equal as is the norm in procellariiform seabirds (Genovart et al 2005, Lawrence et al 2008, Medeiros et al 2012. We assumed the eggs laid produce fledglings according to annual, island-specific, breeding success rates estimated for both modeled populations by Jones et al (2015b) using logistic exposure modeling of burrow survey data from 2006 to 2010.…”

Molecular analysis of faecal samples from birds to identify potential crop pests and useful biocontrol agents in natural areas

“…50 μl of distilled water was then added to each sample and centrifuged at 13,000 rpm for 3 min. 20 μl of InstaGene Matrix was added, the samples were incubated at 50°C for 30 min and then at 100°C for 8 min as described by Medeiros et al (2012).…”