Should I breed or should I go? Manipulating individual state during migration influences breeding decisions in a long‐lived bird species

• Published in: Functional ecology 2023-03, Vol.37 (3), p.602-613
• Main Authors: Grandmont, Thierry, Fast, Peter, Grentzmann, Ilona, Gauthier, Gilles, Bêty, Joel, Legagneux, Pierre
• Format: Article
• Language: English
• Subjects: Anser caerulescens atlanticus; Aquatic birds; Bird migration; Breeding grounds; breeding propensity; Breeding sites; Captivity; carry‐over effects; Clutch size; Documentation; Environmental conditions; experimental stress; Experimentation; Females; Nesting; Parameters; Perturbation; Polar environments; Reproduction; Reproduction (biology); Reproductive effort; snow geese
• ISSN: 0269-8463; 1365-2435
• DOI: 10.1111/1365-2435.14256

Documentation of carry‐over effects (COEs), defined as effects resulting from events that occurred in a previous time period, has largely been observational and understanding of specific mechanisms underlying COEs is still lacking. To investigate this, we simulated an environmental perturbation during the spring migration of a long‐lived bird species and looked at the subsequent effects on various breeding parameters. We captured female greater snow geese Anser caerulescens atlanticus on their spring staging sites and maintained individuals in captivity for up to 4 days before releasing them. We re‐observed females 3000 km North, on their Arctic breeding grounds, to estimate their breeding propensity (i.e. probability of initiating a reproductive event for a given year), and measured their arrival date, laying date, clutch size and nesting success. Only proxies of breeding propensity were affected by our manipulation, which decreased as the time spent in captivity increased. However, females were able to overcome the effects of captivity in two out of the 3 years of experimentation with normal or good environmental conditions at the breeding site. When facing the additional challenge of poor environmental conditions, many individuals manipulated during migration apparently curtailed their reproductive effort by skipping breeding. This experiment is the first to show that breeding propensity is an important parameter affected by COEs resulting from stressful events prior to reproduction in long‐lived species. Read the free Plain Language Summary for this article on the Journal blog. Résumé La documentation des effets reportés (Carry‐Over Effect en anglais, COE), phénomène défini comme étant un effet résultant d'un événement qui s'est produit à un moment antérieur, a été effectuée principalement par observation et la compréhension des mécanismes spécifiques sous‐jacents aux COEs est toujours manquante. Pour investiguer ceci, nous avons simulé une perturbation environnementale durant la migration d'une espèce longévive et avons observé les effets subséquents sur différents paramètres de reproduction. Nous avons capturé des femelles grande oie des neiges (Anser caerulescens atlanticus) sur leur halte migratoire printanière et avons maintenu des individus en captivité jusqu'à quatre jours avant de les relâcher. Nous avons réobservé ces femelles 3000 km au Nord, sur leur territoire de nidification arctique, pour déterminer leur propension à se reproduire (la pro