Skua chick survival rates under two experimental conditions, experimentally fed and siblings contained in separate enclosures

Field observations were made on 49 nests with pairs of chicks. Nests were checked routinely each day with nest activity recorded.

Two experimental manipulations were attempted: (a) to assess whether chick aggression could be tempered by high nutrition levels and (b) whether the real problem was because the second chick left the nest area entirely after dominance was established. To determine if feeding levels influenced chick aggression, skua pairs with 2-egg nests were identified and labelled. As the second chicks hatched, pairs were assigned to experimental (fed each day with dog food) or control groups.