Data and code for: Telomere length decreases with age and reflects early-life environment but not adult condition in a long-lived migratory bird

This data comes from capturing Greater snow geese at their breeding site at Bylot Island (Nunavut, Canada) between 1990 and 2023. Geese were captured in groups of 300 to 400 individuals in August, when they are flightless because they are moulting their flight feathers. Morphometric measurements and blood samples were taken on a total of 4479 adult females and 32673 goslings. We analyzed data for 1084 known age adult females, and blood samples for 92 adults and 23 goslings taken between 2018 and 2023.