Identification d’un Aigle impérial immature en Camargue gardoise durant l’automne 2018

The Eastern Imperial Eagle (Aquila heliaca) is a large raptor breeding from central Europe to the Baikal lake in eastern Siberia. The adult plumage is black-brown, with a yellow-cream nape and white (scapular) shoulders, while juvenile and immature are creme-beige with more or less dark markings depending on the age, the definitive plumage being acquired only in five or six years, after several moults. The Spanish Imperial Eagle (Aquila adalberti), which only breeds in Spain and Portugal, is a very closely related species that was once considered a subspecies. The distinction between the immature of the two species is very delicate, and a confusion is easy: the identification and the determination of the age of a third-year Eastern Imperial Eagle, discovered the 1st of November 2018 in the sector of Mas de Surville (Gard), Southern France, and still present on the 6th of December 2018, were the subject of discussion among birders.
After a presentation of the species and the succession of the different immature plumages, we present the remarkable data of an immature bird in South France and we enumerate the criteria to distinguish it from a young Spanish Imperial Eagle and to age it. We thank Loup Noally, Stephan Tillo, Thomas Krumenacker and Marc Fasol for their photos.