Feather Corticosterone Levels on Wintering Grounds Have No Carry-Over Effects on Breeding among Three Populations of Great Skuas (Stercorarius skua)

Abstract

Environmental conditions encountered by migratory seabirds in their wintering areas can shape their fitness. However, the underlying physiological mechanisms remain largely unknown as birds are relatively inaccessible during winter. To assess physiological condition during this period, we measured corticosterone concentrations in winter-grown primary feathers of female great skuas (Stercorarius skua) from three breeding colonies (Bjørnøya, Iceland, Shetland) with wintering areas identified from characteristic stable isotope signatures. We subsequently compared winter feather corticosterone levels between three wintering areas (Africa, Europe and America). Among females breeding in 2009, we found significant differences in feather corticosterone levels between wintering areas. Surprisingly, levels were significantly higher in Africa despite seemingly better local ecological factors (based on lower foraging effort). Moreover, contrary to our predictions, females sharing the same wintering grounds showed significant differences in feather corticosterone levels depending on their colony of origin suggesting that some skuas could be using suboptimal wintering areas. Among females wintering in Africa, Shetland females showed feather corticosterone levels on average 22% lower than Bjørnøya and Iceland females. Finally, the lack of significant relationships between winter feather corticosterone levels and any of the breeding phenology traits does not support the hypothesis of potential carry-over effects of winter feather corticosterone. Yet, the fitness consequences of elevated feather corticosterone levels remain to be determined.

Temporal overlap and repeatability of feather corticosterone levels: practical considerations for use as a biomarker

“…Samples were reconstituted using assay buffer and assayed in triplicate using Enzo Life Sciences Corticosterone Enzyme Immunoassay (ADI-901-097). This kit has been previously validated for the measurement of feather CORT (Bourgeon et al ., 2014). Assayed samples showed an intra- and interassay coefficient of variation of 4.22 and 13.78%, respectively.…”

A comparison of two methods for the assessment of stress axis activity in wild fish in relation to wastewater effluent exposure

“…As comparative endocrinology converges with ecology and conservation the measurement of endocrine endpoints in wildlife is becoming increasingly common (Cockrem, 2005;Kersey and Dehnhard, 2014) and in this context it is important to understand the factors responsible for inter-population variation in endocrine function (Adams et al, 2013;Bourgeon et al, 2014). The possible role of environmental contaminants in modulating or disrupting endocrine systems in wildlife is of increasing concern in this regard but a comprehensive understanding of the threat is lacking, notably with respect to effects of contaminants on non-reproductive endocrine systems (Bergman et al, 2013).…”

Feather corticosterone content in predatory birds in relation to body condition and hepatic metal concentration

“…Bourgeon et al, 2014;Carbajal et al, 2014;Sepp et al, 2014) but these are in the minority. Concentrations of CORT in feathers have been shown to vary in response to life history events (Bortolotti et al, 2008;Crossin et al, 2013), sibling competition (Yosef et al, 2013), health status (Harriman et al, 2014;Meitern et al, 2013;Mougeot et al, 2010;Sild et al, 2014), overwinter survival (Koren et al, 2012), food limitation , reproductive investment (Fairhurst et al, 2012a;Kouwenberg et al, 2013), and with environmental conditions (Carrete et al, 2013;Fairhurst et al, 2011;Fairhurst et al, 2012b;Legagneux et al, 2013).…”