OF THE UPPER MISSOURI. 153 
BuTEO BOREALIS, Vieill. 
ReEpD-TAILED Hawk. Baird, General Report on Birds, p. 25. 
This hawk is not uncommon throughout the prairie country of the Northwest. It may 
be seen about sunset hovering quietly over the tall grass of the prairie; sometimes sailing 
along as if without an effort; again, poised almost motionless, with head directed toward 
the ground as if intently searching for its prey. When thus engaged in searching for its 
food, it will fly very near the hunter, and often presents itself a fine mark for the gun. 
Its range seems to be, according to Prof. Baird, Eastern North America, Fur countries, 
&e. Three specimens are included in our collection. 
ARCHIBUTEO FERRUGINEUS, Gray. 
SquirreL, Hawk. Baird, General Report on Birds, p. 34. 
This is one of the largest and most beautiful of the hawk kind. It is very rare in the 
Northwest. The only specimen obtained in all our explorations was killed by Lieut. War- 
ren, in the summer of 1856, on the Little Missouri or Teton river, Nebraska. It is 
confined to Western North America. 
Circus Hupsontvus, Vieillot. 
Marsh Hawk. Baird, General Report on Birds, p. 38. 
A very common hawk throughout the Northwest. Its range is given as all of North 
America and Cuba. Four specimens in our collection. 
HALIAETUS LEUCOCEPHALUS, Savigny. 
Bautp Eacus. Baird, General Report on Birds, p. 43. 
This bird was not unfrequently observed during our explorations, and it seems to be 
generally distributed throughout the Northwest. A number of specimens were secured, 
mostly in a young condition. It occurs throughout North America. 
Buzso VIRGINIANUS, Bonap. 
Great HorneD Owt. Baird, General Report on Birds, p. 49. 
Is very common throughout the prairie country of the Northwest. In the winter it 
becomes white, and is often seen by the voyageur of the prairie perched upon some coni- 
cal hill, When the prairie has been burned over by the autumn fires, this bird presents 
quite a conspicuous appearance at a distance from contrast, and may sometimes be mis- 
taken for a bleached buffalo skull. It is distributed throughout the whole of North America. 
Otus WILSONIANUS, Lesson. 
Lon@-EARED Ow. Baird, General Report on Birds, p. 53. 
Not uncommon throughout the Northwest. It was not an unfrequent visitor near our 
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