Climate change is disrupting the precise timing of bird migration relative to food availability, creating ecological mismatches with direct welfare consequences.
Migratory birds arriving at breeding grounds after insect peak face a food availability cliff that causes chick starvation in years of severe mismatch. Parent birds cannot compensate entirely through increased foraging effort for a food supply that has fundamentally declined relative to chick demand. The welfare consequence is widespread chick starvation and reduced fledgling condition that affects survival through the first winter. Adult birds may also face welfare compromise from increased foraging effort during the energy-intensive breeding period. The temporal scale of climate change means migratory bird populations cannot evolve fast enough to track changing phenology, making climate mitigation the only effective welfare intervention at scale.