Class - Aves

• The scientific class Aves includes all birds.
• Birds have feathers, wings, beaks, and scales on their legs and feet. They're also warm-blooded, breathe air, and lay eggs.

Subclass - Neornithes

This subclass includes all species of modern birds, dating back to the late Cretaceous period.

Order - Falconiformes

• Birds in the order Falconiformes have strong bills which are hooked at the tip and sharp on the edges; fleshy ceres (soft skin) at the base of the bills; feet with sharp, curved talons; an opposable hind toe; and keen vision. They are generally strong flyers and carnivores (animal-eaters).
• Because they eat other animals, Falconiformes are commonly called birds of prey or raptors. More specifically, they hunt during the day and thus are called diurnal birds of prey. Owls (Order Strigiformes) are also birds of prey, but they are nocturnal (hunt at night)

Family

• There are five families in the Order Falconiformes.
  
  • The secretary bird belongs to its own family, Sagittariidae. Though classified in Falconiformes, it has many cranelike physical qualities, such as long legs and short, blunt toes.
  • Ospreys belong to the family Pandionidae. This fish-eating species has a unique foot structure within the Order Falconiformes. The outer front toe can swing to face backward with the hind toe, an adaptation for grasping their prey.
  • Accipitridae is a large family which includes kites, Old World vultures, harriers, hawks, eagles, and buzzards. The members of this varied group are believed to be derived from a common kitelike ancestor. Most are active predators and build nests made of sticks. The insides of their eggs are green-tinted.
  • The family Falconidae contains the falcons and caracaras. They're similar to birds in the family Accipitridae, but their bills are notched, they have proportionately longer wings, and the insides of their eggs have a reddish-yellow tint.
  • The family Cathartidae includes New World vultures. Like Old World vultures, they're primarily carrion eaters and have more or less unfeathered heads. Unlike Old World vultures, they don't have a syrinx (voicebox), don't build nests, and their septum (the structure that separates the two nostrils) is perforated.

Genus, Species

• There are 286 species in the Order Falconiformes (Brooke and Birkhead, 1991).
• The family Sagittariidae has one species, the secretary bird (Sagittarius serpentarius).
• Accipitridae is the largest family with 217 species. Bald eagles (Haliaeetus leucocephalus), red-tailed hawks (Buteo jamaicensis), Cooper's hawks (Accipiter cooperii), bearded vultures (Gypaetus barbatus), and cinereous vultures (Aegypius monachus) belong to this family.
• Falconidae has 60 species including the American kestrel (Falco sparverius), peregrine falcon (Falco peregrinus), European hobby (Falco subbuteo), and crested caracara (Polyborus plancus).
• The family Cathartidae has seven species including the turkey vulture (Cathartes aura), black vulture (Coragyps atratus), and the endangered California condor (Gymnogyps californianus) and Andean condor (Vultur gryphus).

Fossil Record

• Fossil remains of a birdlike reptile, Archaeopteryx, have led scientists to believe that birds originated from reptiles in the Jurassic or late Triassic period.
• The first fossil remains of Archaeopteryx were found in Southern Germany in 1861.
  
  • The reptilian features of Archaeopteryx include a dinosaurlike skull with toothed jaws, clawed fingers, a long bony tail, and abdominal ribs.
  • The avian features include a shoulder girdle, pelvis, and leg bones roughly similar to modern birds. Most importantly, Archaeopteryx has feathers.
  • Archaeopteryx belongs to the Subclass Archaeornithes.
• Fossil evidence shows that two other subclasses of primitive birds existed during the Cretaceous period: Enantiornithes and Odontornithes.
• Ancestors of modern birds, Subclass Neornithes, are believed to have originated during the Cretaceous period. During the late Cretaceous and early Tertiary, Neornithes underwent an extensive diversification. By the end of the Eocene, at least 80% of the modern orders of birds had appeared, including Falconiformes (Welty, 1982).