The word “raptor” is used to describe hawks and eagles of the Family Accipitridae, falcons of the family Falconidae, ospreys of the family Pandionidae, and even vultures of the family Cathartidae (although vultures now appear to be most closely related to storks).
The first fossils of raptors consisted of sea eagles, booted eagles, and kites from the Eocene. Paracathartes was a stilt-legged vulture known from the Early Eocene which supports the conclusion that New World vultures evolved from storks. Buteo hawks are known from the Oligocene, falcons, osprey, and Old World vultures are known from the Miocene. The Daggert eagle existed in the Pleistocene in North America. Its long legs indicate that it might have been terrestrial (Weidensaul, 2000).
Haast’s eagle once inhabited New Zealand where it preyed on the giant moas. It could reach 30 pounds, much larger than the 15-20 pounds of the modern harpy eagle or 9 pounds of the golden eagle. One type of goshawk once reached a size similar to eagles, with a weight of about 7 pounds. The tiny hawk measures only 8 inches and specializes in preying on hummingbirds (Weidensaul, 2000)
The bird family Accipitridae is composed of more than 230 species and members of the family can be found throughout the world from tundra to tropical environments (Lerner, 2005). Buteo hawks are closely related to sea eagles with milvine kites forming their sister group. Snake eagles are most closely related to the Old World vultures of the subfamily Aegypiinae. Old World vultures of the subfamily Gypaetinae are most closely related to harrier hawks and kites of the subfamily Perninae (Lerner, 2005; Wink, 1996). Eagles are divided into four subfamilies which are not closely related, Old World vultures are divided into two subfamilies which are not closely related, harriers are divided into two subfamilies which are not closely related, and kites are divided into 3 subfamilies which are not closely related (Lerner, 2005; Wink, 1996). Genetic analyses indicate that falcons, New World vultures, and secretary birds are classified in families outside Acciptridae (Wink, 1996). Genetic analyses indicate that many of the traditionally accepted genera of raptors (such as those of eagles) are actually paraphyletic and new taxonomic relationships should be devised (Helbig, 2005).
have a visual acuity which is 2 ½-3 times as great as human eyes and some
spend at least some of their time soaring on pockets of rising air. Mountain ranges, such as the
Α pair of raptors may maintain multiple nests within a territory and use them every other year. Frequently, both genders help to build the nest.
Female raptors are larger than males, which is unusual among birds. Although most raptors are solitary, a few species can aggregate in flocks during at least part of the year. Some raptors reuse nests from year to year; bald eagles may use the same nest for more than 35 years. The sizes of the average clutch vary in different species of raptor. Bald eagle clutches number 2-3 eggs, red tailed hawk clutches 2-4 eggs, and sharp shinned and northern harrier hawk clutches 4-5 eggs.
(after Weidensaul, 1996).
of juveniles which die in their first year vary in diverse raptor species:
53% of ospreys, 73% red-tailed hawks, 69% of kestrels, 57% peregrine falcons,
70% bald eagles, and 63% red shouldered hawks (Weidensaul,
1996). A Swainson’s
hawk which travels from
A large territory may be required to support a single bird. Bald eagles typically have a territory of 10.4 square miles while that of kestrels is .8 square miles. Red tailed hawk territories vary in size in different environments from .5 to 1.5 square miles. Small raptors such as sharp shinned hawks must consume 25% of their body weight per day. Kestrels consume about 21% of their weight per day. Larger birds consumer a smaller percentage: 12% in peregrines, red-tailed hawks 7-10%, and turkey vultures 10% (Weidensaul, 2000).
falcons, and eagles are at the tops of their food chains, they are vulnerable
to the factors which affect their prey items.
Many raptor species were devastated by the ingestion of the pesticide
DDT which had accumulated in their prey items.
The Egyptian vulture can throw rocks at ostrich eggs in order to break them and this behavior is the only instance known in raptors involving tool use (Weidensaul, 1996). Bones make up the majority of the diet of bearded vultures ( Houston, 2001).A Harris hawk and a sakir falcon are depicted in the following images.
A number of interspecific hybridizations are known to occur within raptors, including peregrine and prairie falcons, peregrine and lanner falcons, merlins and Eurasian kestrels, black and red kites, rough-legged hawks and common buzzards, buzzards and goshawks (although infertile), and a red-backed and Swainson’s hawk (Weidensaul, 2000).