The answer can be found in the beak. This shows clues as to the approximate age of the puffin as it reaches its full length after the first year and then becomes deeper and more curved. Grooves form in the outer red part taking around 6 years to develop three or more.
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An immature puffin less than four years old has fewer than two grooves; a bird between 4 and 6 years old is old enough to breed but may not be doing so has two grooves; and an adult older than 6 years has 3 or more grooves. They are long-lived birds and can reach a grand old age of 40 or more. |