_Milvus leucurus_, VIEILL. Nouv. Dict. Hist. Nat. XX, 556, 1816; Enc.
Méth. III, 1205, 1823. _Elanoides leucurus_, VIEILL. Enc. Méth. III,
1205, 1823. _Elanus leucurus_, BONAP. Eur. & N. Am. Birds, p. 4, 1838;
Consp. Av. p. 22, 1850.—GRAY, Gen. B. fol. sp. 4, 1844; List B. Brit.
Mus. p. 46, 1844.—RICH. SCHOMB. Reis. Brit. Guiana, p. 735.—CASS. B.
Cal. & Tex. p. 106, 1854; Birds N. Am. 1858, 37.—KAUP, Monog. Falc.
Cont. Orn. 1850, p. 60.—HEERM. P. R. R. Rept. VII, 31, 1857.—COOP. &
SUCK. P. R. R. Rept. XII, ii, 149, 1860.—COUES, Prod. Orn. Ariz. p.
12, 1866.—STRICKL. Orn. Syn. I, 138, 1855.—GRAY, Hand List, I, 28,
1869. _Falco melanopterus_, BONAP. Journ. Ac. Phil. V, 28; Ann. Lyc.
N. Y. II, 31; Isis, 1832, p. 1137. _Milvus dispar_, LESS. Man. Orn.
I, 99, 1828. _Falco dispar_, BONAP. Am. Orn. pl. xi, f. 1, 1825; Ann.
Lyc. N. Y. II, 435.—AUD. Am. B. pls. cccli, ccclvii; Orn. Biog. IV,
367, 1831.—TEMM. pl. cl. 319 (_Juv._).—JAMES. (WILS.) Am. Orn. IV. 13,
1831. _Elanus dispar_, CUV. Reg. An. (ed. 2), I, 334, 1829.—LESS. Tr.
Orn. p. 72, 1831.—JARD. (WILS.) Am. Orn. III, 378, 1832.—BRIDG. Proc.
Zoöl. Soc. pt. ii, p. 109; Ann. Nat. Hist. XIII, 500.—AUD. Syn. B. p.
13, 1831.—BREW. (WILS.) Synop. p. 685, 1852.—NUTT. Man. p. 93, 1833.
_E. leucurus_, BREWER, Oölogy.
SP. CHAR. _Adult._ Upper surface, including occiput, nape,
interscapulars, scapulars, rump, upper tail-coverts, and wings
(except lesser and middle coverts), soft, delicate, rather light
bluish-cinereous, becoming gradually white on anterior portion of the
head above. Rest of the head, with the tail, lining of the wing, and
entire lower parts, pure white, sometimes with a very faint tinge of
pale pearl-blue, laterally beneath; two middle tail-feathers ashy, but
much lighter than the rump; shafts of tail-feathers black, except toward
ends. Bristly loral feathers (forming ante-orbital spot, extending
narrowly above the eye), a very large patch on the shoulder, covering
lesser and middle wing-coverts, and large quadrate spot on under side
of wing (on first row of primary coverts), deep black. Under side of
primaries deep cinereous (darker than outer surface); under surface of
secondaries nearly white. Second quill longest; third scarcely shorter
(sometimes equal, or even longest); first longer than fourth. Tail
slightly emarginated, the longest feather (next to outer) being about
.50 longer than the middle, and .60 (or more) longer than the lateral,
which is shortest.
_Male._ Wing, 12.50; tail, 7.10; tarsus, 1.20; middle toe, 1.15.
_Female._ Wing, 12.80; tail, 7.10; tarsus, 1.45; middle toe, 1.35.
Specimens not perfectly adult have the primary coverts, secondaries, and
inner primaries, slightly tipped with white.
Still younger individuals have these white tips broader, the tail more
ashy, and the upper parts with numerous feathers dull brown, tipped
narrowly with white; the breast with sparse longitudinal touches of
brownish.
_Young_ (♀, 48,826, Santiago, Chile, May, 1866; Dr. Philippi). Occiput
and nape thickly marked with broad streaks of dusky, tinged with rusty;
scapulars umber-brown, tipped with rusty; all the feathers of wings
narrowly tipped with white; tail-feathers with a subterminal irregular
bar of dark ashy; breast tinged with rufous, and with badly defined
cuneate spots of deeper rusty. Wing, 12.25; tail, 7.50. (Perhaps not the
youngest stage.)
HAB. Tropical and warm temperate America (except the West Indies), from
Chile and Buenos Ayres to Florida, South Carolina, Southern Illinois,
and California; winter resident in latter State.
Localities: Xalapa (SCL. 1857, 201); Guatemala (SCL. Ibis, I, 220);
Brazil (PELZ. Orn. Bras. I, 6); Buenos Ayres (SCL. & SALV. 1869, 160);
Venezuela (SCL. & SALV. 1869, 252).
Specimens are from Santa Clara, California, Fort Arbuckle, Mirador and
Orizaba, Mexico, Chile, and Buenos Ayres; from all points the same bird.
This species presents a very close resemblance to the _E. melanopterus_
of Europe, and the most evident specific difference can only be detected
by raising the wing, the under side of which is quite different in the
two, there being in the European bird no trace whatever of the black
patch so conspicuous in the American species. The primaries, also, on
both webs are lighter ash, while the ash of the upper parts in general
is darker than in _leucurus_ and invades more the head above, the
forehead merely approaching white. The tail is more deeply emarginated,
and the proportions of the primaries are quite different, the second
being much longer than the third, and the first nearly as long as the
second, far exceeding the third, instead of being about equal to the
fourth. In the _melanopterus_, too, the black borders the eye all round,
extending back in a short streak from the posterior angle, instead
of being restricted to the anterior region and upper eyelid, as in
_leucurus_.
A specimen of “_E. axillaris_” from Australia (13,844, T. R. Peale)
appears, except upon close examination, to be absolutely identical
in all the minutiæ of coloration, and in the wing-formula, with _E.
leucurus_; and differs only very slightly in the measurements of bill
and feet, having these proportionally larger, as will be seen from the
table. Another (32,577, H. Mactier Warfield) has the upper parts so pale
as to be nearly white.
A young specimen of _E. axillaris_ differs from that of _E. leucurus_ as
follows: the occiput, nape, and dorsal region are stained or overlaid by
dull ashy-rufous, instead of dark brownish-ashy; more blackish on the
head. No other differences are appreciable.
A very characteristic distinction between _leucurus_ and _axillaris_
is seen in the coloration of the inner webs of the secondaries: in the
former, they are abruptly lighter than the outer webs, often pure white,
in very striking contrast to the deep ash of the outer surface; in the
latter, both webs are of about the same shade of ash, which is much
paler than in the other race. Occasional specimens of _leucurus_ occur,
however, in which there is little difference in tint between the two
webs.