National Museum, 10; Philadelphia Academy, 2; New York Museum, 2; Boston
Society, 4; Cambridge Museum, 2; Cab. G. N. Lawrence, 2; Coll. R.
Ridgway, 2. Total, 24.
_Measurements._
+----+-----------+-----------+---------+---------+-----------+----------+
|Sex.| Wing. | Tail. | Culmen. | Tarsus. |Middle Toe.|Specimens.|
+----+-----------+-----------+---------+---------+-----------+----------+
| ♂ |11.80–12.50| 7.30–7.60| .66–.80|1.30–1.50| 1.00–1.15| 8 |
+----+-----------+-----------+---------+---------+-----------+----------+
| ♀ |11.60–12.65| 7.20–7.80| .70–.72|1.25–1.40| 1.10–1.20| 8 |
+----+-----------+-----------+---------+---------+-----------+----------+
HABITS. The Black-shouldered Hawk is a southern, western, and South
American species. On the Pacific it is found to occupy a much more
northern range of locality than in the eastern States, where it is not
found above South Carolina and Southern Illinois. Specimens have been
taken near San Francisco in midwinter.
Several individuals of this species, precisely identical with others
from the United States, were taken by Lieutenant Gilliss, in the
astronomical expedition to Chile. Its range in South America does
not appear to be confined, as was supposed, to the western coast,
as specimens are recorded by Von Pelzeln as having been obtained by
Natterer in Brazil, at Ytarare, Irisanga, and San Joaquin, on the Rio
Branco, in August, February, and January. These were taken on the
heights. They are also found in the countries of Mexico and Central
America.
[Illustration: _Elanus leucurus._]
This species has been met with in South Carolina, Georgia, Florida,
Alabama, Mississippi, Louisiana, and Texas, and probably occurs also
in New Mexico and Arizona. Dr. Gambel describes them as very abundant
in California, where they are said to be familiar in their habits, and
breed in clumps of oaks, in the immediate vicinity of habitations. Dr.
Heermann also speaks of them as common in that State. But neither of
these naturalists appears to have met with their nests or eggs. It is
not mentioned either as a bird of Cuba or Jamaica by Mr. Lembeye, Dr.
Gundlach, Mr. Gosse, or Mr. March.
Dr. Cooper speaks of this bird as a beautiful and harmless species,
quite abundant in the middle districts of California, remaining in
large numbers, during winter, among the extensive tulé marshes of the
Sacramento and other valleys. He did not meet with any during winter at
Fort Mohave, nor do they seem to have been collected by any one in the
dry interior of that State, nor in the southern part of California. He
has met with them as far north as Baulines Bay, and near Monterey, but
always about streams or marshes. Their food consisted entirely of mice,
gophers, small birds, and snakes, and they were not known to attack the
inmates of the poultry-yard.
Bonaparte, who first introduced the species into our fauna, received his
specimen from East Florida. The late Dr. Ravenel obtained one living
near Charleston, S. C., which he kept several days without being able to
induce it to eat. Mr. Audubon received another, taken forty miles west
of Charleston by Mr. Francis Lee. This gentleman, as quoted by Audubon,
mentioned its sailing very beautifully, and quite high in the air, over
a wet meadow, in pursuit of snipe. It would poise itself in the manner
of the common Sparrow Hawk, and, suddenly closing its wings, plunge
towards its prey with great velocity, making a peculiar sound with its
wings as it passed through the air. Its cries on being wounded resembled
those of the Mississippi Kite. It was so shy that Mr. Lee was only able
to approach it on horseback.
Audubon states that Mr. Ward, his assistant, found this species breeding
on the Santee River early in the month of March. Their nests were
said to be placed on low trees near the margin of the river, and to
be not unlike those of the common Crow, but without the substantial
lining of its nests. Mr. Ward also mentioned seeing them flying over
the cane-brakes, in pursuit of large insects, in the manner of the
Mississippi Kite, and finding the birds very shy.
In Southern Illinois it has been known to occur as far north as Mount
Carmel, where Mr. Ridgway saw a pair in July, flying about among the
dead trees bordering a lagoon near the Wabash River.
Mr. Audubon, in his visit to Texas, saw several of these birds flying at
a small elevation over the large marshes, and coursing in search of its
prey in the manner of the common Marsh Harrier.
Dr. Heermann found the extensive marshes of Suisun, Napa, and Sacramento
Valleys the favorite resorts of these birds, especially during the
winter, and there they seemed to find a plentiful supply of insects and
mice. They ranged over their feeding-grounds in small flocks from a
single pair up to six or seven. He fell in with an isolated couple in
the mountains between Elizabeth Lake and Williamson’s Pass, hovering
over a small freshwater marsh. In July and August the young were quite
abundant, from which Dr. Heermann inferred that it does not migrate for
the purposes of incubation. Dr. Gambel, who procured his specimens at
the Mission of St. John, near Monterey, describes it as flying low and
circling over the plains in the manner of a _Circus_, and as feeding
on the small birds. It was easy of approach when perched on trees, and
uttered a loud shrill cry when wounded, and fought viciously.
Lieutenant Gilliss, who found them in Chile, describes the nest as
composed of small sticks, and states that the number of the eggs is from
four to six, and that they are of a dirty yellowish-white with brownish
spots. The common name of this Hawk in Chile is _Bailarin_ (from the
verb _bailar_, to dance or balance), from the graceful and easy manner
in which it seems almost to float upward or to sink in the air.
An egg of this species, in the collection of the Boston Society of
Natural History, measures 1.64 inches in length by 1.48 in breadth. In
shape it is very nearly spherical, and equally obtuse at either end. The
ground-color, though nowhere very distinctly apparent, appears to be of
a dull white, strongly tinged with a reddish hue. Distributed over the
entire egg are broad deep flashes of a dark mahogany-brown, intermingled
with others of a similar color, but lighter in shading. These cover the
egg more or less completely, in the greater portion of its surface. This
egg was taken near Fort Arbuckle, Indian Territory, May 9, 1861, by
J. H. Clark, Esq., and sent to the Smithsonian Institution.