Gannet colonies face increasing stress from climate-driven changes in prey fish distribution, with monitoring showing welfare declines in breeding success and adult body condition.
Gannet colony welfare monitoring provides some of the clearest data available on how climate-driven changes in marine prey availability affect individual seabird welfare. Annual monitoring of gannet breeding success, chick growth rates, and adult body condition at major colonies reveals the correlation between North Sea water temperature, sandeel availability, and bird welfare outcomes. In years when warming temperatures push sandeels to deeper or more northerly waters, adult gannets must travel farther to find prey, with energetic costs that reduce adult body condition and the provisioning rate to chicks. Chicks that receive insufficient fish grow slowly and may fledge underweight, with poor survival prospects in their first winter at sea. The welfare harm accumulates: repeated breeding failure years reduce population growth rates and may begin to affect adult survival in colonies where chronic food stress is sustained. The welfare significance of climate change for gannet colonies is that it operates not through acute events but through sustained, progressive change in prey availability that slowly degrades individual welfare and collective breeding success. Policy responses that address the underlying drivers of climate change are ultimately the most important welfare interventions for gannet populations.