282 
CIRCUS CYANEUS. 
and bent downward to a point at about one half the height of the keel. The marginal in¬ 
dentations are large in the young stages, but are always inclosed, becoming smaller in the 
more adult birds. 
GENUS I, CIRCUS. THE HARRIERS. 
Gen. Cn. Bill, not long, well curved, with the cutting edge of upper mandible slightly lobed. Tarsus, long and nearly 
naked. Tail, long, bat is not equal in length to the wings which are considerably elongated. Bower portion of face, sur¬ 
rounded by a ruff. 
Members of this genus not only resemble the owls in having a ruff, or facial disk, hut the ear cavities.are large and the 
plumage is somewhat downy. The leg is strikingly long and the tarsus is naked to the heel behind, but is slightly feath¬ 
ered in front. Four outer quills are incised on the inner webs. The trachea is flattened throughout. The sterno-trache- 
alis is short, having its origin about '25 from the larynx, and there is a slender bronchialis extending overall the half rings, 
but no other laryngeal muscles. The tympaniform membrane is present and although there is a thin os transversale, it 
does not support a semilunar membrane. The walls of the oesophagus are thin; this is at first nearly straight, then is dilated 
into an oblong crop near the middle, after which it is again straight until it opens into a rather small proventriculus with 
simple, oval glands arranged in a zonular band which measures L - 00 in cyaneus, from which this and the following dimen¬ 
sions were taken. The stomach is of medium size, somewhat globular in form, with thin but soft walls and is lined with a 
soft membrane. The fold of the duodenum is long, measuring 3‘50, inclosing a narrow pancreas which extends its en¬ 
tire length. The coeca are merely represented by slight swellings on either side of the intestine. The spleen is an ellipti¬ 
cal body lying directly on the proventriculus. Roth lobes of the liver are equal in size and are short and thick. The heart 
is large, bent slightly to the right and not very pointed. Sexes, not similar in color. There is but one species within oui 
limits. 
CIRCUS CYANEUS. 
Marsh Hawk. 
Circus cyaneus Boie, Isis; 1822, 549. 
DESCRIPTION. 
Sp. Cn. Form, long andslender. Size, medium. Sternum, rather stout, with themarginal indentations varying with 
age. Tongue, short, not very fleshy, and about the same width for nearly its entire length, then abruptly rounded but not 
bifid. Bill and claws, not long. 
Color. Adult male. Above, including upper wing coverts, sides of head, and breast, pale bluish-ash, becoming rufous 
on the back of the head and upper neck. Upper tail coverts, white. Wings, brown, edged on the outer webs with ashy 
and barred with darker. Two middle tail feathers and outer webs of remainder, bluish-ash, and inner webs, rufous, barred 
across the feathers with dark-brown. Under portion of tail, silky whits. Beneath, including under wing and tail coverts 
and tibia, white, spotted with pale reddish. Iris, pale yellow. 
Adult female. Above, brown, with the feathers more or less ashy, edged on the head and neck and spotted on the re¬ 
maining portion with rufous. Beneath, including under wing and tail coverts, reddish-white, darkest on thetibea, with 
every feather having a central spot of reddish-brown, broadest and darkest on the breast, narrower on the neck, smaller, 
rounder and more decidedly rufous on the posterior portions and tibea; otherwise as in the male. 
Young male. Similar to the adult female but decidedly darker above, where there is no trace of ashy but there is more 
rufous on the spottings and edgings. Beneath, very dark rufous, not much spotted, often being wholly immaculate on the 
posterior portion and tibea. Iris, brown. 
Young female. Quite similar to the young male but somewhat lighter throughout, especially below, where the dark¬ 
ening of the rufous is only seen on the tibia. 
Nestlings. Are at first covered with a reddish down, then gradually assume the plumages last described. Iris, brown. 
Bill, bluish-black, cere,greenish, feet, yellow, and claws, brown, in all stages. 
OBSERVATIONS. 
There appears to be considerable variation in specimens, some being darker than others and more heavily spotted, hut 
this may be due to age and sex. Known from all other species by the peculiar ruff about the face combined with the white 
of the upper tail coverts, which is noticeable in all stages. Distributed, as a summer resident, throughout North America. 
Constantly resident in the more southern portions. 
