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Parental care and the transition to independence of Spanish Imperial Eagles Aquila heliaca in Doñana National Park, southwest Spain

1987; Wiley; Volume: 129; Issue: S1 Linguagem: Inglês

10.1111/j.1474-919x.1987.tb03202.x

1474-919X

Juan Carlos Alonso, Luis Mariano González, Borja Heredia, José Luís González,

Animal Behavior and Reproduction

The behaviour of five broods of radio‐tagged Spanish Imperial Eagles Aquila heliaca adalberti was studied in Doñana National Park, Spain during the post‐fledging period. The distance between perching sites and nest, the mean flight duration and distance, the percentage of time spent flying and the home range all increased exponentially with age. As the young got older, the parents spent less time in their vicinity. Young were not seen hunting, but depended on their parents for food. They begged and chased their parents throughout the post‐fledging period, with higher intensity at the end. Nevertheless, the adults became progressively more reluctant to feed them, as reflected in the decrease in feeding frequency and in the number of approaching flights towards the young. At the end of the post‐fledging period, adults often performed aerial displays and frequently chased their offspring. The age of independence of the different young studied varied between 123 and 145 days. The correlations between individual independence and the dates when the young were last fed by their parents, and when the highest intensity of parental aggressive behaviour occurred, were higher than correlations with the variables related to the maturation of flying. Therefore, it is suggested that parental ‘meanness' and aggressive behaviour may be the factors determining the date of juvenile independence and dispersal from the home territory.