94 



foot is suitable for climbing, that of the swift being weaker and fitted 

 mostly for clinging. 



The next striking feature is the great length of the wings, the dis- 

 tance from tip to tip when fully extended being more than 2| times the 

 extreme length of the body. The ratio of these two measurements in 

 most land birds is about as i^ to i. In the swallows it only reaches 2 

 to I ; and the proportion shown in the chimney swift is only exceeded, 

 if at all, by one or two of the hawks and some of the long-winged sea- 

 birds, as the frigatebird and the wandering albatross. 



Referring to the latter it is worthy of notice that in these seabirds 

 the great stretch of wing is due to the lengthening of the inner joint 

 or humerus, the other bones being comparatively short, while in the wing 

 of the swift and all birds of the same order the proportion of the bones 

 is exactly reversed. The radius and metacarj)als, or forearm and hand, 

 make up almost the whole of the wing, the inner joint being so short 

 that the carpal angle is almost covered by the feathers of the shoulder. 

 And there is a corresponding difference in the style of flight. The sea- 

 bird propels itself by long measured sweeps, or soars for whole minutes 

 without a movement, whereas the wing of the swift is constantly a- 

 quiver as he darts and dives hither and thither after the insects that 

 make up his food. Much as the swallows resemble the swifts in colour, 

 size and habit, it is not difficult to distinguish between them when on 

 the wing. The motions of all the swallows are more measured and 

 graceful, being guided by the long rudder-like tail, while the swift might 

 be compared to a short boat without a rudder but having very long 

 oars, not quite suited for following a perfectly straight track, but making 

 splendid time and brilliant steering on a very tortuous course. The 

 small flattened and curved bill looks at first sight ill-suited for its duty 

 of capturing insects in rapid motion, but it will be noticed that the 

 mouth is cleft far beyond the base of the bill, reaching to a point just 

 below the eye, and when wide open the gape is really very great There 

 is an eyebrow or shade over the eye to protect it from the glare of the 

 sun. A similar feature is seen in some eagles, which have a prominent 

 bony shelf above the eye. That of the chimney swift, however, is 

 formed entirely of feathers. 



These birds are late comers with us, most of the swallows generally 



