484 FIELD MUSEUM OF NATURAL HISTORY ZOOLOGY, VOL. IX. 



Length, 21 to 26; wing, 17.50 to 20.50; tail, 7.25 to 10; tarsus, 

 1.90 to 2.30. 



The Osprey, or " Fish Hawk " as it is often called, is a summer 

 resident in Illinois and Wisconsin. While not rare it can not be con- 

 sidered as common. Its food consists of fish which it captures with 

 great dexterity. 



The nest is a large mass of sticks mixed with weeds, usually in a 

 tree or on the top of a dead stump, rarely on rocks or ground. The 

 eggs are from two to four, dull white or buff white, washed and 

 blotched with chocolate and other shades of brown. They measure 

 about 2.45 x i. 80 inches. In Illinois nidification commences the 

 latter part of March, the breeding season lasting until May and occa- 

 sionally later. Birds of this species when not disturbed return to the 

 same nesting ground year after year. 



Suborder STRIGES. Owls. 



Owls are nocturnal birds of prey. There are about 200 species 

 of cosmopolitan distribution, of which some 20 or more occur in North 

 America. Their food consists principally of mammals, but they also 

 kill birds. Some species nest in holes in trees, while others build a 

 rough nest of sticks. The Burrowing Owl deposits its eggs in holes in 

 the ground and the Short-eared Owl chooses a grassy marsh for its 

 breeding place. The eggs of all species are usually two and always 

 white. 



Family ALUCONID^. Barn Owls. 



Genus ALUCO Fleming. 



173. Aluco pratincola (BONAP.). 

 BARN OWL. 



. Strix pratincola Bonap., A. O. U. Check List, 1895, p. 142. 



Distr.: Throughout United States, Mexico, and northern West 

 Indies, more common in southern states, rarely as far north as southern 

 Canada; breeds casually as far north as latitude 40. 



Adult: Upper plumage, tawny or tawny buff, the feathers beauti- 

 fully variegated with gray and spotted with brown and white; upper 



