Taking their name from the mythological winged monsters which were sent by the gods to carry off offenders, the Harpies are among the largest and most powerful birds of prey, and many are the stories current of their prowess. They are comprised in five genera and six species, being mostly natives of Central and South America, with one extending into Mexico and possibly to the southern border of the United States in Texas. The affinities and systematic position of the Harpies have been more or less questioned, some associating them directly with the Buzzards, with which they undoubtedly have a number of points in common, but it seems best to regard them as entitled to full subfamily rank. Aside from certain anatomical peculiarities they differ from the true Eagles in having the posterior side of the metatarsus covered with large transverse plates, thus agreeing with the Buzzards, from which, however, they are distinguished by the presence of a well-defined crest. They have strong bills of moderate length, rather short, rounded wings, and unusually long tails, the latter thought to be of especial assistance in guiding them in their rapid flight among the forest trees, where they often make their home and where they pursue their prey.
The Harpy Eagle (Thrasaëtus Harpyia) is at once one of the most magnificent and powerful of the birds of prey known, having a length of some forty inches and a spread of wing of about seven feet, and its abundant power of flight and voracious nature make it a terror among the birds and mammals where it dwells. Its legs and feet are nearly twice as large and strong as those of any other bird of prey. The prevailing color of the upper parts, including the chest, is black, more or less mottled with gray, while the head and neck are gray, darker on the crest, and the under parts pure white, with the thighs narrowly barred with black, and the tail broadly barred with black and mottled with ashy. The young are ashy gray and black above, with the head, neck, and lower parts white. This species is found in tropical America, ranging south to Bolivia and Paraguay and north to Mexico, rarely extending so far as the mouth of the Rio Grande, thus giving it claim to be called a native of the United States. It frequents the dense forests, where, according to Dr. Oswald, it makes its way with almost incredible swiftness, and “can overtake the swiftest birds of the tropical woods, and in spite of its size steers its way through the labyrinth of forest trees and hanging vines, and rarely fails to rise with a ‘Pheasant,’ a Woodcock, or a small mammal in its claws, after plunging like a meteor from the clouds into the leafy maze of the tierra caliente.” The nesting site commonly chosen is a tall tree of the jungle, or a ledge among the more inaccessible cliffs of the foot-hills, where they build a large structure which is repaired and used from year to year. It is said that the Harpy lays four or five eggs, but never hatches more than two, the remaining eggs according to the native Indians being used to feed the first two Eaglets that hatch. This should perhaps be taken with some allowance, for as a matter of fact the nesting habits are none too well known.
Perhaps best placed here is the powerful Philippine Monkey-eating Forest Eagle ( Pithecophaga Jeferyi), which was first brought to scientific attention about ten years ago. Of large size, exceeding a length of three feet, it has relatively short wings, a very long tail, and naked tarsi and feet, the latter resembling those of the Harpy Eagle, although considerably weaker. The skull is enormous, being very much larger than that of the Harpy, while the bill is extremely narrow and of very great depth, in fact, the depth of the bill is greater than that of any known bird of prey except perhaps Pallas’s Sea Eagle, and the relative narrowness is unique among birds of this order, being only approached by certain Parrots. Mr. Ogilvie-Grant considers it to be most closely related to the Harpy, but Dr. Sharpe places it next the Serpent Eagles (Spilornis). It is a very rare bird, only five examples, so far as known, having thus far fallen into scientific hands. It inhabits the dense and all but impenetrable forests of several of the Philippine Islands, and feeds chiefly upon the green monkey (Macacus), although not infrequently it visits the villages and carries off domestic poultry. It is said to have a strange, wailing cry, but beyond this almost nothing is known of its habits.
The Crowned Harpy (Harpyhaliaëtus coronatus), which ranges over South America and north as far as Guatemala, is about thirty-three inches long, ashy brown above, with a long occipital crest of darker feathers, and paler ashy brown lower parts and blackish thighs. The tail, which is shorter than that of the last species, is black with a broad white median band and a white tip. This bird was found in limited numbers by Hudson in Argentina, where it was usually seen perched on the tall willows along the streams, or soaring in wide circles far up in the sky. The Crowned Harpy is said to prey chiefly on the skunk, as most birds captured bear unmistakable evidence of having been in close quarters with this animal ; but as Hudson suggests, the Eagle may be driven by the pangs of hunger to attack a skunk, but whether they succeed in the attack is quite another matter.
The Guiana Harpy (Morphnus guianensis) of Amazonia, Guiana, and Panama is separated from the others principally by the fact that the tail is of extraordinary length, this being more than four times as long as the very long tarsus. This bird is about thirty-six inches long, the general color above being black, shaded with brown on the margins of the feathers, the head and neck becoming grayish, and most of the under parts white, as are the tips of the upper tail-coverts and upper wing-coverts. The tail is black, tipped with whitish brown and crossed with three bars of ashy brown. This species is confined almost exclusively to the dense tropical forests, being rarely seen in the open country. There is an allied species (M. toeniatus) in Ecuador, and an allied genus with a single species (Harpyopsis novce-guinece) in southeastern New Guinea.