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

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 four 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 measure 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. Howev..., ,