326 POLYBORUS THARUS. 



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. POLYBORID^. THE VULTURE EAGLES. 



'Sternum, more than twice as long as wide and the scapular process of the coracoids meets 

 thefurcula. 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. Cn. Bill, rather lony, 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 numeroas small, simple, closely packed, oval glands arranged in a zonular band which 

 measures T15. 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 beet upon itself several times. The coeca, 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 THARTJS. 



Caracara Eagle. 

 Polyborus lharus CASS., Ills. I; 1854, 113. 



DESCRIPTION. 



SP. CH. Form, not very robust. Size, medium. Tongue, long, fleshy, horny 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 of the same color. Concealed patch on hind 

 neck, brownish-yellow. Wings, more or less handed 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. T!;e 

 feathers above are edged with whitish and those beneath are longitudinally streaked with yellowish-white. Tail, ne.irly 

 white, banded with ashy-brown and tipped with dark-brown. Bill, bluish, cere, red, feet, yelluw, 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. 



