An evaluation of feather corticosterone as a biomarker of fitness and an ecologically relevant stressor during breeding in the wild

Abstract

Feather corticosterone (CORT) levels are increasingly employed as biomarkers of environmental stress. However, it is unclear if feather CORT levels reflect stress and/or workload in the wild. We investigated whether feather CORT represents a biomarker of environmental stress and reproductive effort in tree swallows (Tachycineta bicolor). Specifically, we examined whether individual state and investment during reproduction could predict feather CORT levels in subsequently moulted feathers and whether those levels could predict future survival and reproductive success. Through a manipulation of flight cost during breeding, we also investigated whether an increase in stress level would be reflected in subsequently grown feathers, and whether those levels could predict future success. We found that CORT levels of feathers grown during moult did not (1) reflect past breeding experience (n = 29), (2) predict reproductive output (n = 18), or (3) respond to a manipulation of flight effort during reproduction (10 experimental, 14 control females). While higher feather CORT levels predicted higher return rate (a proxy for survival), they did so only in the manipulated group (n = 36), and this relationship was opposite to expected. Overall, our results add to the mixed literature reporting that feather CORT levels can be positively, negatively, or not related to proxies of within-season and longer-term fitness (i.e., carryover effects). In addition, our results indicate that CORT levels or disturbances experienced during one time (e.g., breeding) may not carry over to subsequent stages (e.g., moult). We, therefore, petition for directed research investigating whether feather CORT represents exposure to chronic stress in feathers grown during moult.

Costs of breeding are rapidly buffered and do not affect migratory behavior in a long‐lived bird species

“…, Harris et al. ). Several recent studies on seabirds have reported on effects of breeding performances on the physiological stress that individuals experienced in different periods along the annual cycle by measuring the CORT concentration in specific feathers (Schultner et al.…”

Corticosterone in feathers of laying hens: an assay validation for evidence-based assessment of animal welfare

“…(2014) , Harris et al. (2016) , and Harris et al. (2017) , whereby samples were incubated with a sheep polyclonal antibody to corticosterone (Corticosterone ELISA Antibody by Enzo Life Sciences Inc.) over 2 h, first.…”

Effects of feather processing methods on quantity of extracted corticosterone in broiler chickens

“…Furthermore, the aforementioned matrices, except for feather, require repeated measurements, which are costly and laborious [15,16]. Several studies reported the presence of corticosterone in the feather of chickens as a putative biomarker of chronic stress [4,11,17], because feather contains information about how corticosterone concentration has changed over time. The feather of birds can be stored at room temperature, and having higher accuracy due to its lower variations, and also the fact that the time point sampling and the output indicates the prolonged stress exposure without repeating the measurements [4,9,10].…”