The single most obvious physiological characteristic that distinguishes all these birds from other carnivorous birds (such as herons or robins) is the set of long, sharp, and powerful talons with which they seize and most often kill their prey.
Raptors are found all over the world except Antarctica. This site focuses on Raptors found in California
What are Raptors?
Derived from the Latin word raptus, meaning ‘seized’ or ‘one who seizes,’ raptor is a general term, which categorizes two unrelated but similar groups of predatory birds that occupy similar niches in the environment: diurnal birds of prey (Ciconiiformes), which include hawks, eagles, kites, falcons, and vultures, and owls (Strigiformes) most of which but not all, are nocturnal in their habits.
Bird Film Strip
The single most obvious physiological characteristic that distinguishes all these birds from other carnivorous birds (such as herons or robins) is the set of long, sharp, and powerful talons with which they seize and most often kill their prey.
In the past, raptors were grouped entirely by such physiological or morphological characteristics. We assumed that the more similar the characteristics, the more closely related the birds. Today DNA analysis has revolutionized the process of identification by uncovering biochemical, or genetic, lines. Birds once classified as part of one group are revealed, through DNA testing, to have a genetic link with an entirely different group. Many of the similarities that used to help us classify these birds, such as the talon, have been revealed as parallel or convergent evolution, in which genetically different groups of animals develop similar characteristics in order to fit into similar niches in the environment.
For example, DNA evidence suggests that while Old World Vultures (those found in Europe and Africa) are genetically related to hawks and eagles, New World Vultures (those found in the Americas) are more closely related to storks and cranes. These two groups of vultures share many characteristics that were developed separately.
While hawks and falcons used to be in an order called Falconiformes, today they are included in a much larger order, Ciconiiformes, which once designated herons and egrets. We now classify hawks and falcons thus: Order Ciconiiformes, Suborder Ciconii, Infraorders Falconides and Ciconiides, and so on down through families, Falconidae (falcons), Accipitridae (hawks), Cathartidae (New World Vultures), on down to genus, species, and subspecies. Each subdivision outlines a part of the species' biochemistry.
Owls are entirely separate, genetically, from hawks, and are classified in their own order, Strigiformes. The fossil record of owls indicates that they are among the oldest groups of living birds. DNA data provided in the 1980s by Sibley and Ahlquist suggest that owl progenitors separated about 80,000 years ago from the line that produced the other large group of nocturnal predators, the goatsuckers and nightjars (Caprimulgiformes). This means that, as with the New World vultures, the physiological similarities between hawks (and their relations) and owls also arose through parallel or convergent evolution.World map
For information on Raptors:Field guides for raptors such as:
National Geographic Birds of North America
A Photographic Guide to North American Raptors, Brian K Wheeler & William S ClarkHawks in Flight, Pete Dunne, David Sibley, & Clay Sutton
Books on hawks and owls such as:
Raptors The Birds of Prey, Scott Weidensaul
Raptors of the World, James Ferguson-Lees & David A. Christie
Owls of the World: Their Lives, Behavior and Survival, Dr. James R. Duncan
