Does Feather Corticosterone Reflect Individual Quality or External Stress in Arctic-Nesting Migratory Birds?

Abstract

The effects of environmental perturbations or stressors on individual states can be carried over to subsequent life stages and ultimately affect survival and reproduction. The concentration of corticosterone (CORT) in feathers is an integrated measure of hypothalamic–pituitary–adrenal activity during the molting period, providing information on the total baseline and stress-induced CORT secreted during the period of feather growth. Common eiders and greater snow geese replace all flight feathers once a year during the pre-basic molt, which occurs following breeding. Thus, CORT contained in feathers of pre-breeding individuals sampled in spring reflects the total CORT secreted during the previous molting event, which may provide insight into the magnitude or extent of stress experienced during this time period. We used data from multiple recaptures to disentangle the contribution of individual quality vs. external factors (i.e., breeding investment or environmental conditions) on feather CORT in arctic-nesting waterfowl. Our results revealed no repeatability of feather CORT within individuals of either species. In common eiders, feather CORT was not affected by prior reproductive investment, nor by pre-breeding (spring) body condition prior to the molting period. Individual feather CORT greatly varied according to the year, and August-September temperatures explained most of the annual variation in feather CORT. Understanding mechanisms that affect energetic costs and stress responses during molting will require further studies either using long-term data or experiments. Although our study period encompassed only five years, it nonetheless provides evidence that CORT measured in feathers likely reflects responses to environmental conditions experienced by birds during molt, and could be used as a metric to study carry-over effects.

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

“…Likewise, on a per mass basis, CORT levels of house finch ( Haemorhous mexicanus ) tail and breast feathers were not significantly different from each other and, although significantly correlated, showed a repeatability of 43% (Lendvai et al ., 2013). In addition, feather CORT levels were not repeatable within individuals across years in common eiders ( Somateria mollissima ) or snow geese ( Chen caerulescens ; Legagneux et al ., 2013), and showed a repeatability of 40% in yellow warblers ( Setophaga petechia ) after controlling for a year effect (23% repeatability before controlling for the year effect; Grunst et al ., 2014). …”

“…In particular, feather CORT levels are often interpreted as indicators of condition or environmental challenge at the location of moult (e.g. Harms et al ., 2010; Legagneux et al ., 2013), predictors of breeding success or survival (e.g. Koren et al ., 2012) or biomarkers of carry-over effects (e.g.…”

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). Feather CORT concentrations have also been shown to be related to problem solving and learning (Bókony et al, 2014), and to feather pigmentation (Fairhurst et al, 2014;Kennedy et al, 2013;Lendvai et al, 2013;Martínez-Padilla et al, 2013).…”

“…Braasch et al, 2011;Harms et al, 2010;Sockman and Schwabl, 2001) may occur during a period when feather growth has ceased, and therefore hormone uptake by the feather is not occurring. We nonetheless included condition as a variable, assuming that for a substantial proportion of individuals CORT accumulation in feathers would coincide with the period during which the bird was exposed to the factor(s) resulting in a persistent change in condition, and if not, that the determinants of condition at time of death were carried over from the period in which feather hormone concentration was accumulated (Legagneux et al, 2013;Harms et al, 2015). In addition to these somatic variables, hepatic metal and metalloid concentrations were available for the group of sparrowhawks included in this study.…”

Pallid bands in feathers and associated stable isotope signatures reveal effects of severe weather stressors on fledgling sparrows

“…Fault bars have been attributed to severe fasting (Slagsvold, 1982), habitat degradation (Sodhi, 2002), physical impairments (Møller, 1989), handling by human observers (King & Murphy, 1984; Murphy, Miller & King, 1989; Negro, Bildstein & Bird, 1994), and disease (Romano et al, 2011). These feather malformations may coincide with endogenous spikes of stress hormones in the blood, particularly corticosterone (DesRochers et al, 2009; Lattin et al, 2011; Legagneux et al, 2013; Jenni-Eiermann et al, 2015), and are thought to form because the deposition of keratin and melanin into the growing feather is disrupted (Riddle, 1908; Michener & Michener, 1938; Wood, 1950; Prum & Williamson, 2001; Møller, Erritzøe & Nielsen, 2009). …”