Golden Eagle
Aquila chrysaetos
By any yardstick the golden eagle qualifies as one of the world’s most magnificent species. Its piercing, bronze-eyed gaze exemplifies the expression "the look of eagles." The species is not restricted to this continent, as our national symbol the bald eagle is; the golden is resident throughout Europe, Asia, and North Africa, as well as North America. It is the most numerous and widespread of the large eagles (eagle species vary greatly in size, and some tropical eagles are no larger than hawks). Adult birds are various shades of dark brown with g olden-tipped feathers on the crown and neck that give the species its name. The tail feathers are a mottled dark gray or brown. Immatures differ in having a great deal of white on the wings and tail. The white tail feathers with the black tip so prized by western Native Americans come from one- or two-year-old birds. As the eagle matures, each yearly molt brings in new feathers with less white. By the time the bird is 5, 6, or 7 years old, the dark tail of maturity has replaced the white tail of youth. The fact that golden eagles take so many years to mature (they do not breed until at least the age of 5) is a clue to their life-span - they are long-lived birds, especially in captivity where they are not subject to hunting accidents, electrocution on high-tension wires, and human persecution. Wild birds live an average of 18 years; captive birds may live 40 years or more. Goldens mate for life, although the survivor will take another mate if one of a pair is killed.
Golden eagles weigh in at 13-15 pounds for a large female, 8-10 pounds for the smaller male (in most raptor species, females are larger than males). Wingspan is over 6 feet, giving the birds spectacular powers of flight. The golden is by choice a bird of the high country, and mountain ridges provide it with updrafts that enable it to soar for hours without a wing beat. Its speed in the air rivals that of the peregrine falcon, although a golden can also quarter a hillside slowly, searching for prey in the manner of a Northern harrier. Its prey is usually a mammal such as a jackrabbit, ground squirrel, or prairie dog. However, the eagle may also stoop like a falcon at birds in flight, catching grouse, pheasants, and ducks on the wing. The young of deer and bighorn sheep are occasionally taken, but not the adults - the golden eagle like other raptors, is an opportunist, and will take the easiest thing it can find. Stories of the species’ lifting ability have been greatly exaggerated, and the birds are simply not capable of flying off with the sheep and deer that some reports have credited (or discredited) them with doing. Goldens are often accused by sheep ranchers of killing lambs, but studies have shown that in the majority of cases where eagles are found feeding from a lamb carcass, the lamb was killed by something else, such as a fall.
The accusation of lamb killing and its reputation as a powerful predator have sometimes cast the golden eagle as a villain. Although the birds now enjoy full legal protection, and are in fact owned by the United States government (this is true of bald eagles as well), they are still subject to illegal shooting. However, the U.S. population seems to be fairly stable at this time, and may number 50,000. The species is classified as threatened, which means that the golden is not considered to be as seriously at risk as the bald eagle. Habitat destruction remains the major threat to this regal species.
For the story of our resident golden eagle, used in our education programs, go to Resident Bird Bios.
It might seem strange to think of the turkey vulture as a bird of prey, but scientists have
put vultures in the order Falconiformes along with eagles, hawks, and falcons.
Editor’s Note: In 1994, the American Ornithologists’
Union’s (AOU) Committee of Classification and Nomenclature
(the nation’s official regulator of avian names)
reclassified all species of New World vultures and no
longer considered them part of the raptor family. They
determined that these vultures are more closely
related to storks. Scientists have been arguing this
point since as long ago as 1873 and extensive studies
and comparisons of the anatomy, physiology, behavior
and cellular biology of hawks, vultures, and storks,
backed by DNA analysis, suggested that vultures and
storks rose from a common ancestor, and that both
should be classified in the same family. Fastforward to 2007: the AOU
questions the above change after further genetic studies suggest that the New
World vultures, the cathartidae, are not closely related to storks. They
"tentatively" return the family to the traditional listing with the
Falconiformes while stating in the Forty-Eighth Supplement to their checklist of
North American birds that their "true phylogenic placement remains uncertain."
However, while other birds of prey
usually hunt for their food, the turkey vulture is primarily a scavenger. The bulk of its food is carrion, usually from
the carcasses of small animals, although the bird will feed upon larger carcasses if they are available. Turkey vultures
are on record as having killed small mammals and nestling birds, although this behavior is the exception, not the rule.
The species is simply not designed for killing. The turkey vulture’s elongated beak lacks the powerfully decurved hook
so typical of other birds of prey, and the vulture’s legs and feet are relatively weak.
Turkey vultures, sometimes called turkey buzzards, find carrion partly by using their keen eyesight as they fly typically a few hundred feet above the ground. As they fly, they keep a watchful eye on other vultures in the area, and when one bird drops down onto a carcass, the others will follow. Turkey vultures also hunt for carrion by using a sense poorly developed or lacking in most birds - a sense of smell. Experiments have shown that turkey vultures have a well-developed olfactory sense, and use it when looking for food.
This is a large bird, with a wingspan of up to 6 feet. Females may weigh from 4½ to 5½ pounds; the smaller males range in size from 3½ to well over 4 pounds. While turkey vultures are sometimes mistaken for eagles in flight, there are several characteristics that distinguish vultures. Their huge wings are two-toned, with the forepart of the wings (as well as the body and long slender tail) blackish, while the rear part is silvery gray. When the vulture soars the wings are held in a slight V, a shape known as a dihedral. As it soars it often rocks or tilts in the wind, and close-up it shows a small red head. Vultures are often seen soaring in groups, and a good place to look for them is over highways, where they are watching for road kills. Eagles, by contrast, have larger heads, shorter, wider tails, are not characteristically found in groups, and soar with wings held flat. Unlike vultures, the much heavier eagles do not rock in flight.
The turkey vulture ranges extensively throughout North America, and is found from southern Canada down into South America. Its range overlaps that of the smaller black vulture in Central and South America, as well as in the southern U.S. However, the black vulture, which lacks the turkey vulture’s red head, is a more southern species, and breeds only as far north as Pennsylvania. In contrast, the turkey vulture breeds as far north as Canada, and is in the process of extending its range northward. It is possible that our expanding highway system is a boon to the bird. It does not construct a nest, but lays its 1 to 2 eggs directly on the ground in caves, in rock shelters, amid boulders, and under fallen trees.
While the turkey vulture wears a naked head, the badge of a carrion eater, in flight the species is undeniably beautiful. The bird’s great wings make it a matchless soarer, and it is a master at riding thermals, hanging almost effortlessly aloft for hours.
The high-diving osprey is in a class - or family - by itself. Technically the bird is considered a hawk, but it has evolved so many adaptations for catching fish that it differs radically from other hawks. Its toes are equal in length, not unequal like the toes of other raptors. The outer toe of each foot is reversible (a trait shared by owls), so fish can be firmly grasped with two toes in front and two in back. The underside of the osprey’s feet is covered with spiny bumps called spicules that help to hold slippery prey. The osprey also flies differently from other raptors. Despite its large size, it is quite capable of hovering, and will frequently do so when scanning the water for fish. In flight the bird shows a characteristic bend or angle in its narrow wings, quite unlike the flat "barn door" shape exhibited by eagles. A black patch just below the wing bend is another field mark. The osprey is almost eagle-sized, up to 2 feet in length and with a wingspan of 4½ to 6 feet. It is a lightly-built bird, however, lacking the bulk that characterizes eagles. Females average about 4 pounds; the smaller males weigh in at about 3 pounds.
The osprey is our only raptor to habitually plunge feet-first into water after fish. By contrast the bald eagle, another fish-eating raptor, snatches fish from just under the surface of the water, only rarely submerging. The bald eagle will also feed willingly on dead fish, something the more fastidious osprey shuns. Although osprey have been observed catching rodents and small birds, the species’ basic diet is fresh fish. A hunting osprey drops toward the water from a height of 30 to 100 feet. The wings are angled back and the feet outstretched. The bird frequently disappears completely beneath the surface of the water with a dramatic splash. Seconds later it reappears, shaking water from its dense plumage like a dog. If its dive has been successfully calculated, the osprey will emerge from the water clutching a fish. This is carried off head first, the better to streamline it.
The osprey is never found far from a seacoast, river, or lake. To attract an osprey, a body of water must contain fairly large, relatively slow-moving fish such as carp, mullet, and shad that swim near the surface. The water must be reasonably clear, so the bird can spot its prey. A breeding prerequisite is a tall structure near the water, on which the osprey constructs a stick-and-flotsam-and-jetsam nest. Tall trees (preferably dead ones) as well as crags are used, and are added to year after year until the nest becomes quite large. Should anything happen to the original tenants, the nest will be taken over by another pair of ospreys. Man-made structures such as utility poles and metal pylons are readily accepted, as are wheels and platforms mounted on poles. The birds will nest near human habitation, although they do not welcome people getting too close.
Osprey numbers suffered a catastrophic decline after World War II. In part this can be blamed on DDT, which played havoc with the bird’s reproductive cycle. The use of the pesticide is now banned, although other problems, such as chemical pollution and illegal shooting, remain. Widespread conservation efforts are paying off, however, and the dashing osprey is once again nesting successfully up and down the Eastern seaboard.
Cooper's Hawk
Accipiter cooperii
Immature Cooper's Hawk
The crow-size Cooper’s hawk is one of three accipiters found in the East (the goshawk and the sharp-shinned hawk are the other two). Accipiters are hawks of the deep woods, and they are not typically seen soaring in the manner of red-tailed hawks or broad-winged hawks. Accipiters have long tails and relatively short, rounded wings to maneuver quickly through trees, and speed and agility are two of their leading characteristics. Their flight pattern, five wing beats followed by a glide, helps to identify them. All three accipiters are shy and secretive birds, preferring the depths of the forest to open spaces, and seldom seen except during migration. The three species are all highly efficient predators, hunting mostly small birds and mammals. Because they may take chickens and game birds, accipiters have been widely misunderstood and stigmatized as villains and bad guys. They were heavily persecuted by man in past years, but now, like all raptors, they enjoy legal protection.
The Cooper’s hawk is intermediate in size between the large goshawk and the small sharp-shinned hawk. The sharp-shinned and the Cooper’s hawk resemble each other so closely that making a distinction between the two species can be very difficult. The Cooper’s hawk is generally the larger, but size is not always easy to judge accurately in the field. Moreover a male Cooper’s hawk and a female sharp-shinned hawk may be very close in size (In most raptor species, females are larger than males.). The tail helps to identify the species. The Cooper’s hawk’s tail is very rounded, and it ends in a white tip; that of the sharp-shinned hawk is square, or even somewhat forked, and it lacks the white tip. Some authorities feel that the Cooper’s hawk is occasionally seen soaring, whereas the other two accipiters are not.
Adult Cooper's Hawk
Adult Cooper’s hawks are a dark slate blue, with a black crown and paler nape. The underparts are a creamy white, marked with wide bands of reddish brown. The long, rudderlike tail bears three dark bands. The eyes are a striking orange or red. Immature or first-year birds are brown, and the eyes are pale amber or yellow. The deep coloration of the adult eye takes two or three years to develop.
Like the other two accipiters, the Cooper’s hawk sports long, unfeathered legs (the very long, thin legs of the smallest accipiter have earned it the name of sharp-shinned hawk). The long legs serve a useful function when the birds are hunting. Should a Cooper’s hawk’s bird quarry dive into brush to escape pursuit, it’s out of luck. The persistent Cooper’s will follow its prey on foot, using the long legs to pluck its hapless victim from cover. The hawk has also been observed hopping about in grass in order to flush out game birds it has located by sound. The Cooper’s is a bold and tenacious hunter. One may occasionally catch a glimpse of the hawk as it speeds to a bird feeder, snatches an unwary songbird, and flashes away.
The reasons are not clearly understood, but throughout the East the Cooper’s hawk population has declined in recent years. The largest accipiter, the goshawk, seems to be expanding its range, while the fierce and colorful Cooper’s hawk seems to be giving way to its big relative.
Great Horned Owl
Bubo virginianus
Any description of the great horned owl must contain a number of superlatives. This formidable bird is the largest, most powerful, and most aggressive owl resident in our area. At 3 pounds, the great horned owl is a top predator, capable of taking prey up to the size of skunks and fox, even porcupines if the bird is hungry enough. Few North American raptors exceed it in size and power. The only owl to do so is the snowy owl (the great gray owl is the longest North American owl, but the bird merely has extraordinarily long, loose plumage - it is outweighed and outpowered by both the snowy and the great horned owl), but the snowy is a placid and unaggressive species. No one has ever called a great horned owl either placid or unaggressive. It is a fierce defender of its young, and is one of the very few birds of prey on record as having killed people. The species ranges from the treeline in Canada down to the tip of South America. Throughout this vast range it varies widely in coloration, depending upon the habitat. Northern owls are pale, in striking contrast to birds from the rainy Pacific coast, which can be almost black. Eastern great horned owls are an overall tawny brown, with each feather barred and blotched with dark brown.
Like other owls, the great horned is hard to spot once it is perched, since it tends to sit motionless, superbly camouflaged by its cryptic coloration. It may be betrayed by its huge yellow eyes, which are as large as those of people. These golden orbs are set rigidly in bony sockets and cannot be moved, so the owl compensates by moving its neck instead. The neck of the great horned owl has 7 more vertebrae than the human neck, resulting in enough extra flexibility to enable the bird to turn its head 270 degrees. Ear-tufts, also referred to as plumicorns, are not ears but clumps of feathers that can be raised or lowered at will. They have several functions, one of them to act as the owl’s mood communicators. They identify their owner as a great horned owl, an attraction for potential mates and a warning to other owl species that are preyed upon by the great horned. Ear-tufts also serve as a camouflage aid. By erecting its plumicorns and pulling its feathers tightly against its body, the owl can look amazingly like a tree branch.
The great horned owl begins nesting duties earlier than any other bird in the East - a female may be brooding a clutch of eggs, typically 2 or 3, in a February snowstorm. For several months prior to nesting the mated pair hoot antiphonally, usually in the wee hours of the morning.
The great horned owl really doesn’t have any natural enemies. However, this top predator has long been viewed unfavorably by another top predator - man. The species was still being bountied in Pennsylvania as recently as the mid-Sixties. Now it is legally protected nationwide, like all other birds of prey, although shooting and trapping still claim victims. Many die each year when they collide with cars while hunting over highways.
For information on our resident foster great horned owls, go to Resident Bird Bios.