ELEVENTH ANNUAL REPORT. Igl 



Thou^^h some of the smaller species of owls feed largely upon 

 insects, there is another nocturnal group of birds which is wholly 

 insectivorous. These are the nighthawks and whip-poor-wills 

 (Caprijiiiilgidac), and in the noiseless flight, large eyes, and dark, 

 mottled plumage we find corresponding resemblances between the 

 two groups. Examination of the internal structure shows that 

 a real affinity exists, the connection being especially clear through 

 the closely-related, fruit-eating, oil-bird (Stcaforjiis) , which is the 

 sole representative of its Family Stcafoniithidac. 



There still remains much to be learned from the structure of 

 owls, but it is probable that if their line of descent could be re- 

 traced, we would find it coalescing sooner with that of the oil- 

 bird and the nighthawks. than with any other living groups of 

 birds. 



ADAPTATIONS OF PLUMAGE AND BODY. 



Owls are eminently fitted for their life — a nocturnil predatory 

 one, and in all parts of their body we find delicate adaptations to 

 this end. L'nlike the nocturnal apteryx the sense of siuell is 

 but slightly developed. In owls, the senses of sight and hearing 

 are the only means used to reveal the whereabouts of the prey. 



Taking the plumage as a whole, we find that each feather is 

 more or less soft and flufifv especially at the tips of the barbs, 

 resulting in a downy condition of the entire outline. The ab- 

 sence of barbicels accounts for this, and on many of the body 

 feathers we find that even barbules themselves are less numerous 

 than on the corresponding feathers of other birds. Even the pri- 

 maries or flight-feathers and the tail-feathers, the stififest and 

 strongest on the body, are surprisingly soft to the touch, and at 

 first thought this softness would seem to be a great disadvantage 

 to the bird in flight. Closer examination of the wing feathers 

 of a barred or screech owl shows that, intrinsically, the vanes are 

 as impervious to the air as those of a pigeon or hawk. There is 

 no radical loss of barbules or barbicels, and hence the feathers 

 are perfectly adapted for flight. An interesting condition, exists 

 however. The barbules along the distal side of each barb are 

 greatly elongated, being often six or eight times as long as the 

 barbules along the opposite side. Near the base of the barbules, 

 the barbicels are as well-developed and numerous as in any bird of 

 strong flight, but the elongated distal portions are soft and flufif}'. 

 and all are bent slightly upward so that ^'^''ey lie on the upper face 

 of the vane. Hence the surface of the feather is covered with a 



