The Bonelli’s Eagle (Aquila fasciata) is a bird of prey of medium to large size with a body length of 65 to 72 cm and a wing span of 150 to 180 cm.

The silhouette of this eagle in flight is very typical with relatively wide wings and almost parallel edges, narrower in the end.

This bird presents, generally, three different plumage stages (juvenile, imature and subadult) each one corresponding to distinct features (Parellada & Viladoms 1984; Real & Mañosa 1992), gaining its adult plumage during the third calendar year. This plumage is characterized by a slightly spotted white chest that makes contrast with the dark colour of the wings. In the dorsal part, it presents a brownish pattern with a distinctive white spot that makes easier the identification of the species (Cramp & Simmons 1979). The tail has a dark distinct band in the end.