58 NORTH AMERICAN OOLOGY. PART I. 



In their habits the European and the American birds are much more decidedly dif- 

 ferent than in their own markings, or in those of their eggs. The American is a very 

 social bird, generally living in large communities during the breeding season. The 

 European is fovind only in solitary pairs. Never, that I can learn, do more than one 

 pair frequent the same neighborhood. The European frequents almost exclusively 

 fresh water. The American, though found also on large rivers and lakes, is much 

 the most abundant on the sea-shore. The European bird rarely builds on trees, the 

 American almost always. The European bird sometimes " builds on the ground 

 among reeds," the American never. The latter rarely resorts to rocky cliffs to breed, 

 the European almost uniformly. There is no instance on record of the American 

 species attacking smaller birds or inferior land animals with intent to feed on them. 

 The European species is know-n to prey on Ducks and other wild-fowl.' In the 

 construction of their nests, the European and the American species approach more 

 nearly, though the former has been known to build them in a manner of which I 

 know of no instances in this country.^ 



Tliese are some of the more prominent points of difference between the Osprey 

 and the Fish-Hawk. They are sufficiently striking, one would think, to have satis- 

 fied naturalists long since of their specific difference, even if no constant variations 

 in size, markings, and other peculiarities of structure, had been noticeable. 



POLYBORUS THAEUS. 



Falco tharus, Molina, Sagg. Stor. Nat. del Chile, 1782. 



Faico cheriway, Jacquin, Beytr. Gesch. der Vog., p. 17. 



Falco plancus, Muller, Cimelia Physica, pi. xvii. 



Pohjloriis vulgaris^ Aud. Orn. Biog. II, 1835, 350 ; VI, 351 ; pi. clxi. 



" " ViEiLL. Nouv. Diet. V, 1817, 257. 



Polylorus hrasiliensis, Aud. Syn. 1839, p. 4. 



" Birds of Am. I, 1840, 21, pi. iv. 

 Polylorus tharus, Cassin, Syn. N. A. Birds, 1854 (lUust. Birds of Cal.), p. 113. 



Birds of GiUiss's U. S. Nav. Astron. Ex. II, 1855, 173. 

 Caracara vulgaris, Gay, Fauna Chilena, Aves, 1855, p. 207, pi. i. 

 VuLG. — Caracara Eagle. Traro. The Mexican Eagle. Totache. Carrancha. 



This species, which appears more nearly connected with the Vultures than with 

 the Eagles in nearly all that relates to its habits, occurs only in the more southern 



1 " An Osprey was seen to stoop and carry off a young, half-grown Duck from the surface of the 

 water, at Slapton Ley. In the struggle the Duck fell from the talons, but was recovered before it reached 

 the water." (Ronnie's edition of Montagu's Ornithological Dictionary, London, 1831, p. 348.) 



^ In Sweden, Oedman states that the Osprey makes its nest in the highest trees, of pine-tops, lined 

 with the leaves of the Polypodium vulgare, a structure very different from any our species are known to 

 build. 



