Old World Vultures

Old World vultures are vultures which are found in the Old World, i.e. the continents of Europe, Asia and Africa, and which belong to the family Accipitridae, which also includes eagles, buzzards, kites, and hawks.
Old World vultures are not closely related to the superficially similar New World vultures and condors, and do not share that group's good sense of smell. The similarities between the two groups of vultures are due to convergent evolution rather than a close relationship. They were widespread in both the Old World and North America, during the Neogene. Old World vultures are probably a polyphyletic group within Accipitridae, with palm-nut vulture, Egyptian vulture and lammergeier separate from the others. Most authorities refer to two major clades: Gypaetinae (the aforementioned species, complemented with the Madagascan serpent eagle) and Aegypiinae (Aegypius, Gyps, Sarcogyps, Torgos, Trigonoceps and possibly Necrosyrtes). The former seem to be nested with Perninae hawks, while the latter are closely related and possibly even synonymous with Aquilinae.
Within Aegypiinae, Torgos, Aegypius, Sarcogyps and Trigonoceps are particularly closely related and possibly within the same genus.
Both Old World and New World vultures are scavenging birds, feeding mostly from carcasses of dead animals. Old World vultures find carcasses exclusively by sight. A particular characteristic of many vultures is a semi-bald head, sometimes without feathers or with simple down. Historically, it was thought that this was due to feeding habits, as feathers would be glued with decaying flesh and blood. However, more recent studies have shown that it is actually a thermoregulatory adaptation to avoid facial overheating; the presence or absence of complex feathers seems to matter little in feeding habits, as some vultures are quite raptorial.