512 The Roller-like Birds 



resemble the Owls least of all members of that group ; the caeca, well developed 

 in the Owls and rudimentary in the Accipitres; the oil-gland, nude or practically 

 so in Owls and tufted in the Hawks and Eagles; and finally the aftershaft, which 

 is present in all Accipitres except the Ospreys, and absent in Owls, except a very 

 minute one in certain Barn Owls. In these characters, however, they agree with 

 the Coraciiformes and are here regarded as a suborder of that group, and placed 

 next the Goatsuckers (Caprimulgi), all, it is assumed, having arisen from a 

 common ancestral stock. 



Structure. The Owls constitute a very natural assemblage of birds and 

 one about the limits of which there is no doubt, since there are but one or two 

 slightly aberrant forms the world over. They are practically cosmopolitan in 

 distribution, ranging from the Arctic regions to the far islands of the sea, some 

 being confined to small islands or equally limited continental areas. They are 

 so well known that an extended description is hardly necessary, yet it may be 

 said that they are birds with compact bodies, short, rather thin necks, very large, 

 rounded heads, and rather short but strong legs and feet, the latter with four 

 toes, of which two are directed forward and two backward, although in most 

 species the fourth toe is reversible and may be directed either way at will. The 

 toes are armed with strong, sharp claws. The bill is strong but relatively short, 

 with the upper mandible strongly curved and the tip turned strongly downward. 

 The bill is provided with a cere through which the nostrils open, but the latter 

 are usually covered by a series of stiff bristles. The most marked feature is 

 the "Owl-face" so called, due to the large eyes, which are directed forward and 

 are capable of but limited motion, and to the radiating disk of feathers surround- 

 ing the eyes. Aside from the great size the eyes are peculiar in other ways, being 

 provided, for instance, with eyelashes, a rare thing in birds, while in closing 

 the eyes the "upper lid is principally effective, the reverse of what is true in most 

 birds." The so-called third eyelid or nictitating membrane is very conspicuous, 

 especially when drawn over the eyes to exclude the bright sunligrft. Many Owls 

 are provided with tufts or crests of feathers above the eyes, producing the so- 

 called horns or ears, although it is perhaps unnecessary to state they have no 

 connection with the true ears, which are usually large and not infrequently fur- 

 nished with a protecting lid or operculum. These ear-tufts, which at least in 

 some cases may be raised or deflected at will, probably serve merely as orna- 

 ments. In certain species there is a curious asymmetry of the skull in the vicin- 

 ity of the ear. The wings are long or moderately so, and usually very broad 

 and rounded; they are comprised of eleven primaries and eleven to eighteen 

 secondaries. The tail is composed of twelve feathers and is usually short and 

 somewhat rounded. 



Plumage. The plumage of most Owls is soft and fluffy, thus often giving 

 an exaggerated impression of the real size, and the colors, as might be expected 

 from their nocturnal habits, are never bright, but consist of a blending or mottling 

 of somber hues. In seeking their prey at night it is necessary that they approach 

 noiselessly, and this end is accomplished admirably by the softness of the plumage, 

 while the mottled colors render them inconspicuous. In such, however, as are 



