Atlantic puffin colonies are sentinel species for ocean health, and their declining productivity provides early warning of ecosystem change.
Puffin chick starvation from prey shifts causes prolonged suffering in burrows as parents bring increasingly inadequate food. Parents that repeatedly bring the wrong prey fish or insufficient amounts experience the stress of failed parental investment. Long-term population declines measured at monitoring sites represent the cumulative welfare cost of chronic prey inadequacy experienced across hundreds of thousands of individual bird lifetimes.