_Archibuteo_, BREHM, 1828. (Type, _Falco lagopus_, GMELIN.)
_Triorchis_, KAUP, 1829 (nec. LEACH, 1816). (Same type.)
_Butaëtes_, LESS. 1831. (Same type.)
_? Butaquila_, HODGS. 1844. (Type, _Butaquila strophiata_, HODGS.)
_? Hemiaëtus_, HODGS. 1844. (Same type.)
CHAR. Similar to _Buteo_, but bill and feet weaker, wings longer, and
tarsi feathers in front, to the toes. Bill small, compressed anteriorly,
but very broad through the gape; upper outline of the cere ascending
basally; nostril broadly oval, nearly horizontal. Tarsus densely
feathered in front and on the sides down to the base of the toes; naked
behind, where covered with irregular scales. Tarsus more than twice
as long as the middle toe; basal half of the toes covered with small
scales; outer toe longer than the inner; claws long, strongly curved,
acute. Feathering of the head and neck normal. Wing very long; the third
to fourth quill longest; first shorter than seventh; outer four or five
with inner webs deeply emarginated. Tail moderate, rounded. Plumage full
and soft.
The relationship of this well-marked genus appears to be nearest to
_Buteo_ and _Circus_, with an approach to _Circætus_ in character of
the plumage, especially the wing. The Old World species, belonging to
the subgenus (?) _Butaquila_, numbering two or three, according to
different authors, I have not seen, and consequently cannot say whether
they are really congeneric with the American species or not. Exclusive
of these, two species are known, both of which belong to North America,
one of them (_A. lagopus_) being found also in Europe and Africa. These
differ very considerably from each other, in the details of external
structure, probably quite as much as they do from the Asiatic forms
above mentioned. The following synopsis will express the differences
between the two North American species, and between the American and
European races of the one common to both continents.
[Illustration:
=54338=, ♀. ½
=54338=, ♀. ½
=54338=, ♀. ½
=54338=, ♀. ¼
=41720=, ♀. ½
=54338=, ♀. ½
41720, _A. ferrugineus_.
54338, _Archibuteo lagopus_.]
Species and Races.
COMMON CHARACTERS. Tail more or less white basally; inner webs of the
primaries white, without bars, anterior to their emargination. Head
and neck with longitudinal streaks of whitish and dusky (except in
melanistic individuals of _lagopus_ var. _sancti-johannis_).
1. =A. ferrugineus.= Wing, 15.90–17.60; tail, 9.50–11.00; culmen,
1.00–1.20; tarsus, 3.10–3.45; middle toe, 1.40–1.65. Bill wide,
the base very broad and depressed. Beneath, continuous pure white,
without conspicuous spots, except sometimes a few scattered ones
along the sides and across the abdomen; breast immaculate, or with
only narrow shaft-streaks. Upper parts always with more or less
rufous. _Adult._ Upper parts and tibiæ fine rufous, the former with
longitudinal spots, the latter with transverse bars, of blackish.
Secondaries and primaries plumbeous, the latter with a hoary cast.
Tail white, washed with pale ash, and more or less stained along the
edges of the feathers (longitudinally) with light rufous; sometimes
with a badly defined indication of a dusky subterminal bar. _Young._
Above dark grayish-brown, with only the borders of the feathers
rufous or ochraceous; tibiæ white, with sparse transverse spots
of dark brown. Tail white only on basal third, and on inner webs,
the remaining portion brownish-ashy, with several more or less
distinct darker bands. _Hab._ Western North America, from Arizona,
California, and Oregon, east to the Great Plains.
2. =A. lagopus.= Wing, 15.75–18.20; tail, 8.70–10.50; culmen,
.80–1.00; tarsus, 2.30–2.80; middle toe, 1.30–1.50. Bill narrow,
compressed; beneath more or less spotted with dusky, which usually
predominates; breast with large spots of dusky; no rufous on upper
parts, nor on tibiæ. _Adult._ Whitish, with transverse dusky spots.
On the lower parts, the dusky spots or cloudings, largest and most
suffused anteriorly (on the jugulum and breast). Terminal portion
of the tail with several irregular dusky bands. (Sometimes almost
entirely black, varying in shade from a brownish to a carbonaceous
tint!) _Young._ Above grayish-brown, longitudinally spotted with
dusky, and more or less edged with pale ochraceous, or rusty
whitish. Beneath ochraceous-white, with the spots largest and most
suffused posteriorly, forming a wide, more or less continuous belt
across the abdomen; markings on the jugulum and breast longitudinal.
Terminal portion of the tail without transverse bars.
Spots on the jugulum, in the adult, suffused into a nearly uniform
patch. Never melanistic (?). _Hab._ Europe …
var. _lagopus_.[91]
Spots on the jugulum, in the adult, scattered. Frequently
melanistic. _Hab._ North America …
var. _sancti-johannis_.
Archibuteo ferrugineus (LICHT).