Many birds are carnivorous—that is, they prey upon other animals for food. All such birds could be considered birds of prey, even a robin in pursuit of a worm. However, the term “bird of prey” is used more precisely for only those birds in either of two orders: Falconiformes and Strigiformes. Falconiformes includes hawks, eagles, vultures, falcons, ospreys, and secretary birds. Strigiformes is made up of owls. Although all these birds share some similarities as predatory birds, scientists believe that the two orders are not closely related. Birds of prey are also called raptors, a term derived from a Latin word meaning “to seize and carry off.” Raptors have hooked beaks and sharp claws, called talons, for grasping, carrying, and killing prey. They hunt and kill live animals or feed upon carrion, which is the flesh of already dead animals, or they may do both. Except for the owls, all raptors have a pouch in the esophagus, called the crop. The crop enables a bird to store food temporarily before digesting it. Parts of the prey that the bird cannot digest, such as fur or feathers, are formed into pellets in the stomach and expelled out the beak. Raptors are very strong, usually large birds. In most species the female is significantly larger than the male. Raptors typically have very keen vision and good hearing but usually little or no sense of smell. They are found nearly all over the world in a great variety of habitats, including jungles, tundras, deserts, grasslands, temperate forests, and urban areas. The birds of the orders Falconiformes and Strigiformes differ in important ways. Those of Falconiformes are nearly all diurnal. This means they hunt and are otherwise active primarily during the day. The birds of Strigiformes are nocturnal, or night, hunters. Other differences between these orders will be explored in the following specific family descriptions. Day-Flying Raptors - Red-tailed hawk (Buteo jamaicensis).
The hawk family (Accipitridae) is the largest and most diverse in Falconiformes. Its members range from the tiny African sparrowhawk, which is little larger than an ordinary cardinal, to the huge great harpy eagle and Himalayan griffon vulture, which have wingspans of 6 1/2 feet (2 meters) or more. Eagles, hawks, kites, harriers, and Old World vultures are the members of the hawk family. Hawk Family - Great harpy eagle (Harpia harpyja).
Of the eagles the great harpy eagle ( Harpia harpyja) is notable for its large size. It is a powerful bird with white, gray, and black plumage and is native to Central and South America. Like most eagles, it usually preys on animals less than half its size. An exaggerated fear of eagles has caused humans to needlessly kill these birds. Partly because of this, the great harpy eagle is one of the world's rarest birds. Until fairly recently, the bald eagle (Haliaeetus leucocephalus), which is native to North America, was also becoming rarer. This bird is no longer endangered, thanks to many years of effort by conservationists. It is not really bald, but has a white-feathered head. The bald eagle is the national symbol of the United States. A type of sea eagle, it lives near bodies of water and eats fish, along with other prey. Another magnificent raptor of the Northern Hemisphere is the golden eagle (Aquila chrysaetos), so named for the bright brown plumage on its neck. Like most other eagles, golden and bald eagles have broad wings that are excellent for soaring, build stick nests in trees or on cliffs, and lay a small clutch of eggs. Most eagles prey on freshly caught mammals, birds, reptiles, or other animals, but some also eat carrion. - Eurasian sparrowhawk (Accipiter nisus).
The so-called true hawks are often mistaken for eagles. However, they have a swifter attack and are generally smaller. Known for their excellent hunting skills, which combine strength with speed, hawks are sometimes used as trained hunting birds. One that is so employed is the northern goshawk ( Accipiter gentilis). This bird, one of the largest hawks, lives in the Northern Hemisphere and is gray with dark gray bands on its undersides. These bands are typical of hawks, as are the short, broad wings and long tail that allow it to fly low and fast and to maneuver well. The goshawk is a typical hawk also in that it lives in wooded areas, builds a platform nest usually in a tree, lays two to five eggs, and feeds mainly on birds and small mammals. Other typical hawks are the sharp-shinned hawk ( A. striatus) and Cooper's hawk ( A. cooperii), both of North America. Among the least known of the hawk family are the kites. These relatively small, lightly built birds prey on the snakes, birds, and insects that inhabit their usually marshy habitats. The black kite (Milvus migrans), found in the warm areas of Asia, Africa, and Europe, is one of the few kites that eat carrion. The Everglade, or snail, kite (Rostrhamus sociabilis) has a specialized, slender bill adapted to its diet of almost exclusively snails. It is found in certain areas of North, Central, and South America. Kites usually lay one to five eggs in nests that they construct in trees. Harriers, slender birds with long legs and tails, inhabit grasslands and marshes. The best-known harrier is the marsh hawk (Circus cyaneus), which is also called the hen, or northern, harrier. It is found mostly in the Northern Hemisphere. All harriers have a disc of facial feathers, which gives them an owlish appearance. As in an owl, this disc directs sound to the bird's ears to help it locate prey. Harriers hunt by flying slowly and low to the ground and then dropping rapidly on small animals. Usually harriers lay four to six eggs in nests close to the ground (which is unusual for any bird of prey, as most prefer nests that are high and inaccessible). Of the birds of the hawk family, the Old World vultures look the least like hawks. These generally brown or black birds are found exclusively in the Eastern Hemisphere, where they inhabit the warm parts of Europe, the dry parts of southern Asia, and most of Africa. They are sometimes called buzzards, a term that more commonly denotes hawks of the genus Buteo. New World vultures are distinct from Old World vultures and are not members of the hawk family. The word vulture indicates the basic nature of these birds: it comes from a Latin word meaning “breeze scavengers.” Rarely flapping their large wings, vultures float on rising air currents searching for dead animals, the greater part of their diet. This cruising ability allows vultures to conserve energy, since many days may pass between meals. Most vultures have a large crop in which to store carrion. This also helps the birds survive lean times. Although vultures can kill prey, they rarely do. They have relatively weak feet and lack sharp talons. One Old World vulture, the palm-nut vulture (Gypohierax angolensis) of Africa, eats mainly plant matter, the fruits of the oil palm. The lappet-faced vulture, also of Africa, is one of the largest vultures. As is typical of most Old World vultures, these birds generally roost and hunt in groups and have no sense of smell. Most Old World vultures lay one to two eggs in nests built in trees or on rock ledges. The male and female both aid in hatching the young. Unlike in most other raptors, in most vultures the male is somewhat larger than or about the same size as the female. New World VulturesThe New World vultures are quite different from the Old World vultures. They belong to a separate family, the Cathartidae. Some scientists believe that these vultures may be more closely related to storks than to other birds of prey and do not belong in the order Falconiformes; other scientists disagree. New World vultures are found, as is indicated by their name, only in the Americas. The heads and necks of New World (and some Old World) vultures are bare of feathers. These birds have a sense of smell, which is especially notable in the turkey vulture (Cathartes aura). New World vultures build no nests, laying their eggs in tree hollows or in caves or on the ground. The turkey vulture is the most common of these birds, and the king vulture (Sarcoramphus papa) is the most colorful, being yellow, orange, purple, black, and white. The California condor (Gymnogyps californianus) is perhaps the best known in this group, unfortunately because it is one of the most endangered of all vultures. With a wingspan of nearly 10 feet (3 meters), it is the largest flying bird of North America. This bird's range once included much of the southwestern United States as well as Mexico, but by the early 1980s there were fewer than 25 of the birds left in the world. In the late 1980s the last of the wild California condors were taken into captivity to be protected and bred. Beginning in 1992 many California condors that were born and raised in captivity were released into the wild. The related Andean condor (Vultur gryphus) of South America has a 10.5-foot (3.2-meter) wingspan. After the albatross, it is the world's largest flying bird. Falcon Family - Peregrine falcon (Falco peregrinus).
The falcon family (Falconidae) includes falcons and caracaras. Falcons look like streamlined hawks. Characterized by long, pointed wings, they are among the most agile hunters of the birds of prey. The hunting sport of falconry, a favorite pastime of the nobility of the Middle Ages and still popular in some parts of the world, involves the training of these birds to hunt other birds ( see falconry). Although goshawks are sometimes used for falconry, the peregrine falcon ( Falco peregrinus) is chosen most often. It is found across Europe, Asia, and the United States. The peregrine is a fairly typical falcon: it is a medium-sized bird; it dives swiftly at prey; it does not build a nest; and it lays its eggs on ledges or cliffs, in natural hollows, or in the old nests of other birds. Most falcons kill and eat birds, mammals, reptiles, or insects, but some also eat carrion or plant matter. Unlike hawks, eagles, and vultures, falcons rarely soar and glide. Their flight is one of strength and swiftness. The gyrfalcon (Falco rusticolus), an inhabitant of Arctic regions, is the largest of the falcons. In looks and behavior, caracaras are quite different from falcons. They are limited in range to the Western Hemisphere, in particular to Central and South America. Caracaras have distinctive long legs and patches of bare, reddish skin on or near the face. They eat carrion as well as living animals and plant matter and lay two to three eggs in nests of sticks that they make in trees or cacti. They are like falcons in their swift, flapping flight and in their generally medium size. The largest of the caracaras, the crested caracara (Polyborus plancus), inhabits the southwestern United States and parts of Central America. It is about 2 feet (0.6 meter) long and has a wingspan of 4 feet (1.2 meters). OspreyThe family Pandionidae consists of only one species, the osprey (Pandion haliaetus). Like falcons and caracaras, ospreys are medium-sized birds. Also known as fish hawks, they are particularly noted for their method of seizing their favorite prey—fish—by plunging feetfirst into the water. And, as is typical of most raptors, the osprey has strong feet and sharp talons. Ospreys live in most temperate and tropical regions of the world, near rivers, swamps, or other bodies of water. They make stick nests at the top of trees and other elevated structures, such as utility poles, where the females generally lay three eggs. Secretary Bird - Secretary bird (Sagittarius serpentarius).
The family Sagittariidae also has only one species, the secretary bird ( Sagittarius serpentarius). It is found primarily in central and southern Africa. The secretary bird is a long-legged bird. It has a crest of black feathers projecting outward from its head, which resembles the quill pens that secretaries used to stick behind their ears. These birds are notable because they do not hunt by flying. Instead, they walk on the ground looking for small animals, mainly snakes, which they disable by kicking. Thick scales that cover the birds' legs protect them from snakebite. Secretary birds usually lay two eggs in nests made in low trees. Night-Flying Raptors—Owls - Common barn owl (Tyto alba).
There are not as many different kinds of night-flying raptors (in the order Strigiformes) as there are of day-flying birds of prey (in the order Falconiformes). Strigiformes is made up of two families of owls: the barn owls and the typical owls. Owls live in nearly all parts of the world in a variety of habitats, especially woodlands and forests. - With a length of about 8 inches (20 centimeters) or less, the pygmy owl (any of several species of …
Owls vary in size from the tiny pygmy owls to the large eagle owls. They range in length from about 5 to 28 inches (13 to 70 centimeters) and in wingspan from about 1 to 6.6 feet (0.3 to 2.0 meters). However, owls are easy to recognize, and there are more similarities between owls than there are differences. In general, owls have very keen hearing and eyesight that is extremely sensitive to any movement in dim light. Their large eyes are situated in the front of a large, rounded head, which can rotate about 270° (three quarters of a circle). The face is flat, with a small hooked beak and a facial disc of feathers that focuses sound toward the ears. Some birds in the family of typical owls have tufts of feathers over their ears. All owls have soft feathers that allow for “silent” flight, which is an aid in hunting. These birds have rounded wings, short tails, and powerful feet with sharp talons. Owls are thought to eat only animals—typically rodents and other small mammals, small birds, or insects. They usually bolt their food down whole and then eject the indigestible parts in the form of pellets. There seems to be no regularity in their breeding seasons. Most species do not build nests. They typically lay two to seven eggs in hollows in trees or cliffs, in other birds' nests, or in human structures. As is true with most of the day-flying raptors, the female owls are usually larger than are the males. Ecological ImportanceBirds of prey are important in the ecological balance; they scavenge and dispose of carrion, control rodent populations, and eat various pests that are harmful to crops. These helpful birds are, unfortunately, especially susceptible to extinction, partly because of natural evolutionary selection and partly because of human interference. Human agriculture, deforestation, and population growth have severely limited the areas of habitation for these birds. Raptors, being generally quite large, need a considerable amount of space for their territories. With less and less space available, and therefore, less food from which to choose, raptor populations have been diminishing. In addition, birds of prey, as is common with most large birds, lay relatively few eggs. Pesticides have also harmed the birds. Moreover, humans have intentionally killed many raptors indiscriminately because of a usually unfounded belief that raptors kill livestock. Many birds of prey have become extinct or are endangered because of these factors. Governments and organizations, especially since the 1960s, have tried to strengthen world conservation efforts for these birds. (See also bird.) |