ABSTRACT
This chapter looks at the physical form, evolution and hunting and breeding ecology of Serpent and Snake eagles of the subfamily Circaetinae. These are generally broad-winged, medium to large eagles, with a mostly snake diet, although the Bateleur and Philippine eagles which may also take mammals. This Subfamily Circaetinae includes five genera and sixteen species. The Genus Circaetus includes the Banded snake-eagle, Beaudouin’s snake-eagle, Black-chested snake-eagle, Brown snake-eagle, Fasciated snake-eagle, and Short-toed eagle. The Genus Eutriorchis includes the Madagascar serpent-eagle, the Genus Pithecophaga the Philippine eagle, the Genus Spilornis the Andaman serpent-eagle, Crested serpent-eagle, Great Nicobar serpent-eagle, Kinabalu serpent-eagle, Philippine serpent-eagle, Sulawesi serpent-eagle, and the Genus Terathopius the Bateleur eagle. Some species have been described as fierce and handsome, with members of the Genus Circaetus described as having very large heads crowned with fan-like expandable crests, a reticulate pattern of heavy scales on the tarsi and comparatively relatively short toes. Recent studies have also found genetic links with the Old World vulture group Aegypiinae. The largest of this group, the Philippine eagle, may be more closely related to the snake eagles than to the physically similar harpy eagle group.
