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POLYBORUS THAR US. 
The Ospreys breed early in February on the St. John’s River, placing the nest in 
high cypress trees, and I also found fresh eggs about the middle of March at Clear Water 
Harbor on the west coast. The birds in these sections, were very unsuspicious, allowing 
one to pass directly under the nest without flying, and in one instance, my assistant was 
half-way up a tree in which a bird had her domicile, before she started. On the Keys, 
where the nests are frequently placed in low mangroves but a few feet from the ground, 
the birds breed earlier. Further north, where the Ospreys are migratory, they do not 
breed until the middle of April. 
FAMILY VIII. PO LYBORIDiE. THE VULTURE EAGLES. 
Sternum , more than twice as long as wide and the scapular process of the coracoids meets 
the furcula. Marginal indentations , two, inclosed. 
This family, in our section, is represented by a single genus. The bill is strong, well- 
curved, with the cutting edge of upper mandible nearly straight. Lores and space around 
eye, naked. The tarsus is long and only slightly feathered in front. The toes are weak 
and the claws are small. 
GENUS I. POLYBORUS. THE CARACARAS. 
Gen. Ch. Bill, rather long, strong, and well-curved, with the cutting edge of upper mandible slightly lobed. Tail and 
wings, long, the former is rounded and the latter are pointed. 
The trachea is a little flattened throughout. The sterno-trachealis is short and stout, having its origin quite near the 
larynx, and there is a slender bronchialis extending over all the half rings, but there are no other laryngeal muscles. The 
walls of the oesophagus are thin; this is at first nearly straight, then is dilated into a crop, and is again straight and opens 
into a large sized proventriculus with numerous small, simple, closely packed, oval glands arranged in a zonular band which 
measures 1* 15. The stomach is of a 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, and is bent upon itself several times. The cceca, when present, are 
very small. The spleen is a spherical body lying on the proventriculus. The left lobe of the liver is slightly larger that 
the right. There is but one species found within our limits. 
POLYBORUS THARUS. 
Caracara Eagle. 
Polyborus tharus Cass., Ills. I; 1854, 113. 
DESCRIPTION. 
Sp. Ch. Form, not very robust. Size, medium. Tongue, long, fleshy, homy at tip, where it is rounded and bifid. 
Occipital feathers, elongated. Space on breast, naked. Sexes, similar in color. 
Color. Adult. Above, dark-brown everywhere, excepting upper tail coverts which are yellowish-white, banded with 
dusky. Tail, white at base, black at tip, and crossed with numerous bands ofthe same color. Concealed patch on hind 
neck, brownish-yellow. Wings, more or less banded with white. Beneath, everywhere white, with abroad band across 
abdomen and tibia, dark-brown, and the breast is transversely banded with fine lines of black. . 
Young. Similar to the adult but duller brown above which color also extends over the entire lower portions. The 
feathers above are edged with whitish and those beneath are longitudinally streaked with yellowish-white. Tail, nearly 
white, banded with ashy-brown and tipped with dark-brown. Bill, bluish, cere, red, feet, yellow, and iris, brown, in all 
stages. 
OBSERVATIONS. 
Specimens appear to present some variation of plumage but may be readily known by the form and colors as described. 
Distributed as a constant resident in Mexico and northward into the United State as far as Arizona and eastward into 
Louisiana and Florida. 
