[2] They are generally medium-sized birds of prey inhabiting Europe, Asia, Africa, New Guinea and Australia.

[3] The genus Hieraaetus was introduced in 1844 by the German naturalist Johann Jakob Kaup with the booted eagle as the type species.

[13] This could create a taxonomic problem: the booted eagle is the type species of Hieraaetus, moving it would make that name a junior synonym of Aquila.

[19] Some authorities retain Bonelli's eagle and the African hawk-eagle in Hieraaetus.

Also, some retain Wahlberg's eagle in Aquila, whilst still recognizing Hieraaetus as a separate genus.