From the abstract: “We found that Spheniscus penguins have pale feet at hatching and the feet become darker with age throughout the lives of individuals. We showed that we can accurately predict the age structure of a colony of Magellanic penguins Spheniscus magellanicus, but not the ages of individual penguins, based on a sample of foot colors.”
Authors: Ginger Rebstock, Pearl Wellington, Dee Boermsa
Journal: PeerJ
DOI: https://doi.org/10.7717/peerj.17937