Breeding behaviour
Breeding penguin, with a flipper band and two chicks.
Adélie penguins nest in colonies of up to a million birds. The advantages of this are that a bird's chances of finding a mate are increased, and there is safety in numbers. On the other hand, nesting in colonies leads to competition with other penguins for breeding space, food, and partners. These social factors all interact with each other and with the physical factors that influence breeding (i.e. food and nesting space) to determine how successfully a bird will breed. In order to identify individuals so that the social factors involved in breeding can be investigated, we need to band birds.
Each year several hundred chicks and adults (the number varies from colony to colony) are fitted with a metal band that fits snugly around the top of the left flipper. Each band has an individual number that can be read with binoculars from a distance of up to 20 m. Banding birds allows us to:
- Permanently identify individual birds
- Track the fate of individual birds so we can investigate:
- Survival
- How long penguins live
- Age at first breeding (the average is 5 years)
- Mate choice
- Breeding site choice and, linked to this, the level of natal philopatry (birds returning to breed in the same colony they were born in)
- The age of a penguin, especially if it was banded as a chick
- The extent of movement between colonies (immigration/emigration rates)
- The age structure of a colony ( how many 1-year-olds, 2-year-olds etc. there are)