A History of North American Birds, Land Birds. Volume 3. Robert Ridgway
of Antenor, but primaries longer and more pointed, the fourth usually longest, and the outer three or four with inner webs cut. Bill and feet as in Asturina. Tail moderate, or rather short, nearly even, or slightly rounded.
¶¶ Front of the tarsus densely feathered down to the base of the toes.
14. Archibuteo. Feathering of the tarsus interrupted behind by a bare strip along the full length; middle toe less than half as long as the tarsus. Nostril broadly oval, obliquely horizontal; bill weak, the upper outline of the cere much ascending basally. Feathers of the nape normal, blended. Third to fourth quills longest; outer four or five with inner webs cut.
15. Aquila. Feathering of the tarsus uninterrupted behind; middle toe more than half as long as the tarsus. Nostril narrowly oval, obliquely vertical; bill strong, the upper outline of the cere nearly parallel with the lower. Feathers of the nape lanceolate, distinct. Fourth quill longest; five to six with inner webs cut.
** No trace of membrane between outer and middle toes.
16. Haliætus. Tarsus feathered in front one third, or more, of the way down; the naked portion with an imperfectly continuous frontal, and less well defined posterior, series of transverse plates, and covered elsewhere with roundish granular scales. Feathers of the neck, all round, lanceolate, distinct. Bill very large, the chord of the culmen more than twice as long as the cere on top; nostril oval, obliquely vertical. Third to fifth quills longest; outer six with inner webs cut. Tail rounded or cuneate, sometimes consisting of fourteen feathers.
The foregoing diagnoses embrace merely the more conspicuous external characters whereby the genera may be most readily distinguished by the student. The following table presents additional accompanying characters afforded by the osteological and anatomical structure, of more importance in defining with precision the several groups embraced in our fauna.
A. Scapular process of the coracoid produced forward so as to meet the clavicle42 (Huxley). Nasal bones almost completely ossified, the nostril being a small, usually circular opening, with a raised or “rimmed” margin, and conspicuous, usually central, bony tubercle. Inferior surface of the supermaxillary bone with a prominent median angular ridge. Superciliary process of the lachrymal consisting of a single piece. (Falconinæ.43)
B. Scapular process of the coracoid not produced forward so as to meet the clavicle (Huxley). Nasal bones incompletely ossified, the nostrils being very large, and without bony rim or tubercle. Inferior surface of the supramaxillary bone without a median ridge. Superciliary process of the lachrymal variable. (Accipitrinæ.)
a. Superciliary process of the lachrymal composed of a single, excessively abbreviated piece;44 posterior margin of the sternum with a pair of indentations, and without foramina. (Pandion and Nauclerus.)
b. Superciliary process of the lachrymal double, or composed of two pieces, joined by a cartilaginous “hinge,” and reaching nearly across the orbit. Posterior margin of the sternum without indentations, and usually with a pair of foramina. (All except Pandion and Nauclerus.)
† Septum of the orbits and nostrils incompletely ossified (the former always and the latter usually) and with foramina; posterior margin of the sternum most produced backwards laterally, and incompletely ossified, there being usually a pair of foramina. Intestinal canal short, broad, with the duodenum simple, forming a single loop (McGillvray). A well-developed “web” between the outer and middle toes. (All but Haliætus.)
†† Septum of the orbits and nostrils completely ossified, and without any trace of foramina; posterior margin of the sternum produced medially into a convex lobe, and without any trace of foramina. Intestinal canal extremely elongated, attenuated, with the duodenum arranged in several convolutions (McGillvray). No trace of a web between outer and middle toes. (Haliætus.)
Subfamily FALCONINÆ
Genus FALCO, Auct
Gen. Char. Bill strong, its breadth at the base equalling or exceeding its height; upper outline of cere on a level with, or rather lower than, the base of the culmen; gonys much arched, the chord of the arch equalling about half that of the culmen. Near the tip of the upper mandible is a prominent tooth on the commissure, and near the end of the lower mandible, which is truncated, is a deep notch corresponding; the end of the upper mandible is compressed, giving the situation of the tooth an inflated appearance when viewed from above. Nostrils circular, with a conspicuous central tubercle. Orbital region bare; projecting superciliary shield conspicuous, arched, but not very prominent. Tail shorter than wing, the feathers hard and stiff. Primaries very strong, elongated, tapering rapidly toward their points; only the first or first and second with their inner webs emarginated, the cutting being angular, and near the end of the quill. Tarsus never with a single series of transverse scutellæ either in front or behind; middle toe very long.
13077, ♀. ½
One primary only with inner web emarginated; first to second longest; first longer than fourth.
Tarsus longer than middle toe, and feathered far below the knee; first quill shorter than third. Coloration of the sexes alike; old and young slightly different in pattern and tints. Size large … Hierofalco.
Tarsus not longer than middle toe, and scarcely feathered below the knee; first quill equal to or longer than the third. Coloration of the sexes alike; old and young very different in pattern and tints. Size, very small to large … Falco.
Two primaries with inner webs emarginated; second to third longest; first shorter than fourth.
Basal joint of toes without transverse scutellæ; tarsus about equal to middle toe.
Coloration of the sexes in adult plumage very different in tints; in the young alike, the young ♂ resembling the adult ♀. Size small … Æsalon.
Basal joint of toes with transverse scutellæ; tarsus longer than middle toe.
Coloration of the sexes very different, in pattern and tints, at all ages; old and young alike. Scutellæ of the toes and tarsus interrupted at the digito-tarsal joint; tarsus much longer than middle toe. Bill small, the cere on top less than one fourth the culmen. Size small … Tinnunculus.
Coloration of the sexes alike at all ages; old and young slightly different in pattern and tints. Scutellæ of tarsus and toes uninterrupted from “knees” to claws; tarsus but little longer than middle toe. Bill large, the cere on top about one third the culmen. Size medium; form very slender … Rhynchofalco.
Hierofalco, Cuvier, 1817. (Type, Falco gyrfalco, Linn.)
Jerafalco, Boie, 1822; Kaup, 1851. (Same type.)
Gennaia, Kaup, 1847. (Type, Falco jugger, Gray.)
1. F. gyrfalco. Wing, 13.00–17.00; tail, 8.50–11.50; culmen, .85–1.05; tarsus, 2.10–3.00; middle toe, 1.80–2.25.45 Ground-color varying from entirely pure white to wholly dusky, but generally bluish (in adult) or grayish-brown (in young) above, and white beneath. Adult. All the markings transverse.46 No lighter nuchal band. Young. Markings of the lower surface longitudinal, the upper parts without transverse bars (except on the tail47).
a. Lower parts with white predominating, or wholly white.
Lower tail-coverts never with markings. No tinge of blue anywhere on the plumage, the ground-color of which is entirely pure white at all ages.
1. Adult. Upper parts, excepting head and neck, with transverse crescentic
As in all the
Embracing besides the
As in the Polyborine forms of the
Extremes of sixty specimens.
Sometimes there are more or less distinct linear streaks on the head and neck, or on the pectoral region.
Sometimes the irregular markings above have a transverse tendency.