A History of North American Birds, Land Birds. Volume 3. Robert Ridgway
Strix pratincola.
4886. Otus wilsonianus.
7272. Scotiaptex cinereum.
7899. Nyctale richardsoni.
414. Scops asio.
773. Bubo virginianus.
628. Nyctea nivea.
7897. Surnia ulula.
428. Glaucidium ferrugineum.
437. Spheotyto hypogæa.
(All natural size.)
12088.
504.
49808.
504.
A.
49808.
12088. Nyctea nivea. (Ear copied from Swainson, F. B. A)
504. Scotiaptex cinereum.
49808. Surnia ulula. (Ear copied from Swainson.)
A. Brachyotus “cassinii.” (Left ear and nostril, from fresh specimen.)
Family FALCONIDÆ.—The Falcons
Char. Eyes directed laterally, and eyelids provided with lashes. Toes invariably naked, and tarsus usually naked and scutellate (feathered only in Aquila and Archibuteo). Outer toe not reversible (except in Pandion). Head never with ear-tufts, and never wholly naked (except in the Vulturinæ, of the Old World).
The above characters are about the only readily observable points in the external anatomy in which the Falconidæ differ strikingly from the Strigidæ and Cathartidæ, and may serve to distinguish the birds of this family from those of the two others. The osteological characters, however, as expressed on page 1328, are more decided and important in a taxonomic point of view, and serve to separate the Hawk family as a well-defined group.
In the following treatment of the North American Falconidæ, I confine that part relating to the systematic arrangement strictly to the species embraced within the province of our work, for the reason that in a forthcoming monograph of all the American species I hope to present a systematic classification based upon the species of the whole world. All preliminary details regarding the general characteristics and distinctive peculiarities of the family, as well as all discussions and generalizations upon the subject, will therefore be omitted here.
The following synopsis of the North American genera is intended as an artificial arrangement which may enable the student to identify, by simple and readily understood characters, the forms belonging to this country.40
Genera
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.
As in the case of the
By this is meant that they are all of equal length and thickness, and not progressively smaller from the posterior one to the outer, as in all