CHIMNEY SWIFT 283 



Voice. — The notes of the swift remind ns of the bird itself — ener- 

 getic and quick; sharp and hard like the bird's stiff wings. The 

 note most commonly heard as the birds shoot about over our heads 

 is a bright, clear, staccato chip or ^^.si/i.-— whichever suggests the 

 sharper sound— often repeated in a series and sometimes running 

 off into a rapid chatter. The chip note varies little, if at all, except 

 for the quiclmess of the notes, and seems to punctuate the bird's 

 ceaseless rush through the air. Sometimes, when the birds are very 

 high in the air, the chattering call comes down to our ears, soft- 

 ened by distance — like sparks slowly falling to the earth after a 

 rocket has burst. 



Simple as these notes are, the birds introduce a good deal of 

 variety into them by modifying the interval between them, thereby 

 changing the expression of their lively theme. 



One modification, which I have mentioned under "Courtship," hav- 

 ing heard it only in the breeding season and only when the birds 

 were under stress of excitement, serves to illustrate this ability and 

 may be regarded as representing the song of the swift. It is made 

 up of a long series of notes in which the birds, after giving several 

 isolated chips, change abruptly to a series of very rapid notes, a 

 sort of chatter, then, with no pause between, change back to the 

 chijos, then back again — chips-chatter-chips, and so on. We may 

 term it the "chips and chatter call." 



Another modification of the chip note, often heard in summer 

 when the birds are in a comparatively quiet mood, is a long chatter 

 in which the volume increases and lessens, suggesting the sounding 

 of a minute watchman's rattle. 



There is one note quite different in quality from the above notes 

 and less frequently heard than any of the variations of the chip. 

 This is a musical monosyllable — sometimes divided into two syl- 

 lables — a squeal, almost a high whistle with a slight upward in- 

 flection, like eeip, sometimes repeated once or twice. I have heard it 

 both in spring and fall; hence it cannot be, as I once thought it 

 was, a note of immature birds. 



Field marks. — The swift may be distinguished readily from any 

 of the swallows by the shape of its wings and the manner in which 

 it moves them. Swallows' wings are roughly triangular, the tri- 

 angle seeming to join the bird's body by a fairly wide base, whereas 

 the swift's wings are narrow at the base — they are pointed, and 

 slightly curved like the terminal part of a sickle's blade — and appear 

 to be set on well forward. 



The stroke of the swift's wing gives a jerky, hurried effect com- 

 pared with the more leisurely movement of a swallow, and the 

 tips of the wings are not swept backward, even when the birds are 



