Glucocorticoids, state-dependent reproductive investment and success in the face of danger in a long-lived bird

• Published in: Journal of Ornithology
• Main Authors: Noreikienė, Kristina, Jaatinen, Kim, Steele, Benjamin B., Öst, Markus
• Other Authors: Academy of Finland, Suomen Kulttuurirahasto, Societas pro Fauna et Flora Fennica, Otto A. Malm Lahjoitusrahasto, Oskar Öflunds Stiftelse, Svenska Kulturfonden, Nordenskiöld-samfundet, LUOVA Doctoral Programme in Wildlife Biology, European Regional Development Fund and the programme Mobilitas Pluss, the Faculty Development Fund of Colby-Sawyer College, Abo Akademi University
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer Science and Business Media LLC 2020
• Subjects: Somateria mollissima
• Online Access: http://dx.doi.org/10.1007/s10336-020-01847-9; https://link.springer.com/content/pdf/10.1007/s10336-020-01847-9.pdf; https://link.springer.com/article/10.1007/s10336-020-01847-9/fulltext.html

Abstract Glucocorticoid hormones may mediate trade-offs between current and future reproduction. However, understanding their role is complicated by predation risk, which simultaneously affects the value of the current reproductive investment and elevates glucocorticoid levels. Here, we shed light on these issues in long-lived female Eiders ( Somateria mollissima ) by investigating how current reproductive investment (clutch size) and hatching success relate to faecal glucocorticoid metabolite [fGCM] level and residual reproductive value (minimum years of breeding experience, body condition, relative telomere length) under spatially variable predation risk. Our results showed a positive relationship between colony-specific predation risk and mean colony-specific fGCM levels. Clutch size and female fGCM were negatively correlated only under high nest predation and in females in good body condition, previously shown to have a longer life expectancy. We also found that younger females with longer telomeres had smaller clutches. The drop in hatching success with increasing fGCM levels was least pronounced under high nest predation risk, suggesting that elevated fGCM levels may allow females to ensure some reproductive success under such conditions. Hatching success was positively associated with female body condition, with relative telomere length, particularly in younger females, and with female minimum age, particularly under low predation risk, showing the utility of these metrics as indicators of individual quality. In line with a trade-off between current and future reproduction, our results show that high potential for future breeding prospects and increased predation risk shift the balance toward investment in future reproduction, with glucocorticoids playing a role in the resolution of this trade-off.