Читать книгу A History of North American Birds, Land Birds. Volume 3 - Robert Ridgway - Страница 16

A. Nasal bones almost completely ossified, the nostril being a small orifice, with a conspicuous central bony tubercle; its form nearly or quite circular, or linear and oblique (in Polyborus), with its upper end the posterior one Falconinæ.

1. Falco. Nostril circular. Commissure with a prominent tooth and notch; lower mandible abruptly truncated and notched. Primaries stiff and hard, and more or less pointed, the first to the second longest, and the outer one or two with their inner webs cut, the angular emargination being near the end of the quill. Middle toe much more than half as long as the tarsus; claws strongly curved, very acute.

2. Polyborus. Nostril linear, oblique, the upper end the posterior one; commissure without prominent tooth nor notch; lower mandible not distinctly truncated or notched. Primaries soft, obtuse, the third longest, and the outer four or five with their inner webs cut, the shallow sinuation being toward the middle of the quill. Middle toe less than half the tarsus; claws weakly curved, very obtuse. Face and cheeks naked, and scantily haired.

B. Nasal bones very incompletely ossified, the nostril being a large, more or less oval, opening, of oblique direction, its lower end being invariably the posterior one; without a bony tubercle, and never perfectly circular. (Accipitrinæ.)

a. Sides of the head densely feathered close up to the eyelids.

3. Pandion. Outer toe reversible; claws contracted and rounded on their under surface, and not graduated in size.41 Wing long, third quill longest; outer four with inner webs emarginated. Tail rather short, rounded.

4. Nauclerus. Outer toe not reversible; claws not contracted or rounded on under side, and graduated in size. Wing long, third quill longest; outer two with inner webs sinuated. Tail excessively lengthened and forked, the lateral pair of feathers more than twice as long as the middle pair.

b. Sides of the head with a more scantily feathered orbital space, with a projecting superciliary “shield” covered with a naked skin.

* A well-developed membrane, or “web,” between the outer and middle toes at the base.

† Tarsus about equal to the middle toe.

§ Claws short and robust; two outer quills with their inner webs cut.

5. Ictinia. Commissure irregularly toothed and notched; front of tarsus with transverse scutellæ. Tail emarginated; third quill longest.

6. Elanus. Commissure without irregularities; front of tarsus with minute roundish scales. Tail double-rounded; second quill longest.

§§ Claws long and slender; five outer quills with inner webs cut.

7. Rostrhamus. End of bill bent downward, with a long pendent hook; inner edge of middle claw slightly pectinated, or serrated. Tail emarginated; third or fourth quill longest.

†† Tarsus very much longer than the middle toe.

¶ Front of tarsus unfeathered, and, with the posterior face, covered with a continuous series of broad transverse scutellæ.

α. Form very long and slender, the head small, the tail and legs long and claws excessively acute; bill weak, compressed, very high through the base, the culmen greatly ascending basally, and the cere much arched; commissure usually with a very prominent “festoon.”

8. Circus. Face surrounded by a “ruff” of stiffened, differently formed feathers, as in the Owls. Tarsus more than twice as long as the middle toe. Wing very long, hardly concave beneath; third to fourth quill longest; outer four with inner webs sinuated.

9. Nisus. Face not surrounded by a ruff. Tarsus less than twice as long as the middle toe. Wing short, very concave beneath, the outer quill much bowed; third to fifth quills longest; outer five with inner webs sinuated.

β. Form short and heavy, the head larger, the tail shorter, the legs more robust. Bill stronger, less compressed, lower through the base, the upper outline less ascending basally, and the cere less arched. Commissure variable.

10. Antenor. Form heavy, the wings and tail moderately long, and feet very robust; bill rather elongated, the commissural lobe prominent, and the base of the culmen somewhat depressed. Fourth quill longest; outer five with inner webs cut. Lores naked, and almost destitute of bristles.

11. Onychotes. Outstretched feet reaching beyond end of tail; tibial plumes short, close, not reaching below the joint. Wing short, rounded, very concave beneath, the fourth quill longest; outer five with inner webs sinuated. Tail short, but little more than half the wing, slightly rounded. Claws very long, and extremely acute.

12. Asturina. Bill and feet as in Antenor; lores densely bristled; wing short, rounded, concave beneath, the third to fourth quills longest; outer four with their inner webs cut.

13. Buteo. Form 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.)