No. 1. 
REPORT UPON BIRDS COLLECTED ON THE SURVEY. 
BY A. L. HEERMANN, M. D. 
HYPOTRIORCHIS FEMORALIS, Gray. 
Plate I. 
Falco femoralis, Tf.mm. PI. Col. I, plate 121.— Cassin, in Gen. Rep. P. R. R. Survey, IX, 1858, 11. 
Sp. Ch .—Male. —Head, wings, and back, of a light slate color; the primaries being of a darker hue, and ou^their inner 
vanes barred with white, with which also the larger coverts are tipped. A white line, starting from above the eye, extends down 
the occiput, becoming rufous as it forms a collar on the hind neck. A deep slate colored moustache descends from the aDgle 
of the mouth one half inch on the throat; auriculars are of the same color. Chin, white. Breast, orange or yellowish white, 
and in some specimens marked with elongated spots of black. Abdomen, thighs, and under coverts of the tail, rufous. Sides 
and flanks, dusky black ; each feather being banded with delicate transverse white lines, and often uniting so as to form a band 
in front at the junction of the breast and abdomen. In some specimens this band does not appear, as the dusky black feathers 
do not in all cases extend across the abdomen. Tail, of a light gray slate color, is composed of twelve feathers traversed by 
nine white bars; the ends of all these feathers being tipped with white except the two centre ones. Legs, yellow. Bill, yellow, 
tipped with bluish black. Length, 14 inches. 
The female resembles the male in its plumage, but its colors are less brilliant and marked. 
The young bird has the back and tail of a dusky brown,^each feather being fringed with a narrow border of lighter shade. 
The primaries and tertiaries are edged with white. Breast yellowish white, covered with a broad band of dusky black, extend¬ 
ing down to the thighs; these feathers often being edged with light clayish yellow. Moustache and auriculars, dusky brown. 
I saw this bird twice on the vast plains of New Mexico, near the United States boundary line, 
before procuring it; flying over the prairies in search of small birds and mice, and at times 
hovering, as is the wont of our common sparrow hawk, (Tinnunculus sparverius.) We possess 
little information relative to its habits from those authors who have written on this bird. It 
appears to be a resident of Surinam, Cayenne, Brazil, Chili, and other portions of South America 
and is used in Chili for hunting the partridge. Besides this species, the Mexican ibis, also from 
South America, comes yearly to incubate in California; and further researches will doubtless 
still add to our fauna from that continent and Mexico. 
Superadded to their sharp talons and powerful beaks, the family of the Falconidae , to which 
this interesting species belongs, possesses strength and daring to a high degree. They nourish 
themselves exclusively on living animals, disdaining to devour that which they have not captured 
by their own address. Necessity forcing them to range over a large extent of country for their 
food, they naturally become wanderers. Assimilating in pairs during the breeding season 
many species remain so mated during life ; though not indispensably necessary to one another 
each being able to provide for itself, yet by mutual assistance in the pursuit of prey the opera¬ 
tion of procuring subsistence is vastly simplified and facilitated. 
2 c 
