Ontogeny and individual heterogeneity of the corticosterone stress response in a wild altricial seabird, the snow petrel (Pagodroma nivea)

Abstract

In the current context of global change, there is evidence of a large inter-individual variability in the way animals physiologically respond to anthropogenic changes. In that context, the Hypothalamus-Pituitary-Adrenal (HPA) axis and the corticosterone stress response are of primary importance because they are thought to govern the ability of individuals to adjust to stress. Several studies have reported that this stress response is variable among adults and they have successfully linked this variability with abiotic and biotic factors. However, the inter-individual variability of the glucocorticoid stress response has rarely been examined during the developmental phase in wild vertebrates, and its potential ecological determinants remain unclear. In this study, we examined the ontogeny of the corticosterone stress response in an altricial seabird species (i.e., how corticosterone levels increase in response to a standardized stress protocol), the Snow petrel. We reported a strong heterogeneity of the corticosterone stress response at all ages in snow petrel chicks (11-, 20-, and 37-days old chicks). Although the magnitude of this corticosterone stress response decreases with the age of the chick, we also found that this corticosterone stress response was repeatable throughout the post-hatching developmental period (repeatability: r > 0.50 for stress-induced corticosterone levels after a 30-min restraint). Importantly, this glucocorticoid stress response was negatively associated with the body condition of the chicks (i.e., mass corrected for body size), and previous exposure to sampling was associated with a dampened corticosterone stress response. However, we did not find any link between parental traits (parental condition or parental corticosterone stress response), nest quality, hatching date, and the chick’s corticosterone stress response. Our study suggests that the corticosterone stress response is a consistent individual trait that is affected to some extent by post-natal conditions, and which differs among individuals very early in life.

Corticosterone release in very young siblicidal seabird chicks (Rissa tridactyla) is sensitive to environmental variability and responds rapidly and robustly to external challenges

“…The HPA axes of black-legged kittiwake chicks are sensitive to internal and external cues and are capable of mounting a large glucocorticoid response to an acute challenge (restraint) during a developmental window of intense social interaction with both siblings and parents. While this is consistent with the hypothesis that glucocorticoids are important for species with intra-brood competition, the ability of young chicks to mount an adult-like HPA response to restraint has been found in a number of other seabird species that have one-egg clutches, including three species of petrels (Adams et al, 2008; Angelier et al, 2022; Sagar et al, 2019), three species of alcids (Benowitz-Fredericks et al, 2015; Kitaysky et al, 2005; Will et al, 2015), and a congener of the black-legged kittiwakes studied here: the red-legged kittiwake (Kitaysky et al, 2001; though red-legged kittiwakes historically had larger clutch sizes). Thus, sibling competition cannot be the sole selective pressure on the development of HPA axis activity.…”

How does maternal age influence reproductive performance and offspring phenotype in the snow petrel (Pagodroma nivea)?

“…Specifically, chicks from older females have higher stressinduced CORT levels, suggesting that they have a higher adrenocortical stress sensitivity (prediction 5). Elevated stress-induced CORT levels are classically associated with a poor body condition and with nutritional stress in chicks (Kitaysky et al 2001;Pravosudov and Kitaysky 2006;Love and Williams 2008;Angelier et al 2022). Our result on stress-induced CORT levels is therefore surprising because we did not find any relationship between maternal age and offspring body condition.…”