_Ictinia_, VIEILL. 1816. (Type, _Falco mississippiensis_, WILSON.)
_Nertus_, BOIE, 1826. (Type, _Falco plumbea_, GMELIN.)
_Pœcilopteryx_, KAUP, 1844. (Same type.)
[Illustration: ♂ =1485=, R. R. ½
_Ictinia mississippiensis._]
[Illustration: ♂ =1486=, R. R. ¼
_Ictinia mississippiensis._]
[Illustration:
=32974=, ♀. ½
=32974=, ♀. ½
=32974=, ♀. ¼
_I. plumbea._]
GEN. CHAR. Form falcon-like; the neck short, wings long, and pointed,
the primaries and rectrices strong and stiff, and the organization
robust. Bill short and deep, the commissure irregularly toothed, and
notched; gonys very convex, ascending terminally; cere narrow; nostril
very small, nearly circular; feet small, but robust; tarsus about equal
to middle toe, with a distinct frontal series of broad transverse
scutellæ; claws rather short, but strongly curved, slightly grooved
beneath, their edges sharp. Third quill longest; first of variable
proportion with the rest. Tail moderate, the feathers wide, broader
terminally, and emarginated.
This genus is peculiar to America, the two most closely related genera
being _Elanus_ on the one hand and _Harpagus_ on the other. Its species
belong to the tropical and subtropical regions, one of them (_I.
plumbea_) generally distributed throughout the intertropical portions,
the other (_I. mississippiensis_) peculiar to Mexico and the southern
United States.
In their habits, they are very aerial, like the genus _Nauclerus_,
sailing for the greater time in broad circles overhead, occasionally
performing graceful evolutions as they gyrate about. Like _Nauclerus_,
they are also partially gregarious, and, like it, feed chiefly on
insects and small reptiles, which they eat while flying.
Species.
COMMON CHARACTERS. _Adult._ Uniform plumbeous, becoming lighter
(whitish) on the head, and darker (blackish) on the primaries and
tail. Inner webs of primaries with more or less rufous. _Young._
Beneath whitish, striped longitudinally with brownish; above much
variegated: tail with several narrow whitish bands.
1. =I. mississippiensis.= _Adult._ Wings lighter than the tail, the
secondaries hoary whitish; inner webs of primaries with only obscure
spots of rufous, the outer webs with a very obscure stripe of the
same. Tail wholly black. _Young._ Stripes beneath reddish-umber;
lower tail-coverts with longitudinal shaft-streaks of the same.
Second to third quills longest; first shorter than seventh and
longer than sixth. Wing, 10.60–12.30; tail, 6.00–7.00; culmen,
.60–.65; tarsus, 1.30–1.55; middle toe, 1.00–1.10. _Hab._ Prairies
and savannas of the southern United States and Northern Mexico, from
Wisconsin and Georgia to Mirador.
2. =I. plumbea.=[75] _Adult._ Wing concolor with the tail, the
secondaries black; inner webs of the primaries almost wholly
rufous; outer webs with only a trace of rufous. Tail with about
three bands of pure white, formed by transverse spots on the inner
webs. _Young._ Stripes beneath brownish-black; lower tail-coverts
transversely spotted with the same; upper parts darker. Third quill
longest; first shorter or longer than the seventh. Tail more nearly
square. Wing, 10.50–12.20; tail, 5.60–6.80; culmen, .62–.70; tarsus,
1.15–1.50; middle toe, 1.00–1.05. _Hab._ Tropical America, from
Paraguay to Southern Mexico.
Ictinia mississippiensis (WILSON).