Large difference in fledging date of two juveniles from the same golden eagle Aquila chrysaetos eyrie in the Basque Mountains. Important ecart des dates d'envol dans une aire d'aigle royal Aquila chrysaetos des montagnes basques.

摘要

In a Golden Eagle eyrie of in the western Pyrenees, both fledglings left the nest at an interval of 18 ([plus or minus]2) days. A large hatching asynchrony, the sex of the first hatched chick, a female, a longer rearing period for the second nestling, a male, account for this unusual delay. It is suggested that a key factor was the food supply, characteristic of this Pyrenean mountain zone: prey availability was sufficient to prevent fratricide but still limited the growth rate of the second chick.