Black-legged kittiwakes have declined by 70% in Britain since the 1970s, closely tracking changes in sand eel availability driven by sea surface warming. Their population trajectory is an indicator of North Sea ecosystem health.
Kittiwake welfare is severely compromised during years when sand eel availability is poor. Adults unable to find adequate prey for chicks repeatedly dive without success, burning energy reserves. Chicks that receive insufficient food starve to death on cliff ledges over days -- a welfare harm that occurs simultaneously across thousands of nests in poor prey years. The kittiwake decline is a graphic illustration of how climate change creates welfare crises at population scale that individual conservation interventions cannot easily address without tackling the root cause.