WHITE-THEOATED SWIFT 317 



On August 3, the swifts were flying about in the canyon when first observed 

 just at sunset. A crude estimate made of tlieir numbers in the air gave from 

 one hundred to two hundred individuals. Prior to entering the night roost 

 the birds streamed in a procession into the shadows by it and then turned out 

 into the light of the canyon. Shortly thereafter they entered the rock, stream- 

 ing in with unbelievable rapidity. Three or four struck the crevice simul- 

 taneously, and now and then they struck one another. Twenty or more entered 

 in an interval of one or two seconds. The entire flock was housed between 

 7 : 20 and 7 : 25 p. m., and a constant chattering thenceforth welled from the 

 rock face. The sun had set some time previously, and deep shadows filled the 

 gorge of the canyon. 



On September 21, a similar performance was witnessed, but the 

 number had decreased to approximately 49 birds ; these all entered the 

 rock in exactly two minutes, between 6 : 30 and 6 : 32 p. m. On Oc- 

 tober 24, "the birds went into .the roosting niche as fast as shot poured 

 through a funnel ; faster than the tongue could waggle in an attempt 

 to count." They all entered within a space of ten seconds. Later 

 observations were made in November and in January; at the latter 

 time only about a dozen swifts were seen to use the roost. 



Voice. — Dr. Alexander Wetmore (1920) says: "The call note of 

 this bird is a shrill laughing he he he he heard usually when two or 

 three are coursing along together." Ralph Hoffmann (1927) writes: 

 "In spring and during the breeding season while pursuing each other 

 about the cliffs in which they nest they utter a shrill twitter, sug- 

 gesting the syllables tee-dee, dee, dee, dee.''"' Mr. Hanna (1909) de- 

 scribes the vocal powers more fully, as follows: "The swifts do not 

 seem to have any musical ability, but their notes or calls are pleasing, 

 especially to one who is studying them. One series of peculiar shrieks 

 is given while the bird is in rapid flight and is suggestive of joyous 

 freedom. Another series of notes is given when the birds are in the 

 crevices, which sound very much like the twitterings of small chickens 

 as they cuddle under their mother's wings, only the swifts' notes are 

 much louder. These twitterings are quite a contrast to the wild 

 slirieks, and they cannot help but suggest comfort and satisfaction." 



Field mp/rks. — White-throated swifts are very apt to be associated 

 with violet-green swallows, when insects are flying low and the birds 

 are coursing about at no great height above the ground; at such 

 times it is often confusing to try to pick out the swifts, as they dart 

 about among the swallows. But the shape of the swift is very distinc- 

 tive, with its long, narrow wings set, as it sails, in the form of a 

 cross; and its wing strokes, as it flies, are much more rapid than 

 those of the swallow. Moreover, the swallow is all white on the 

 under parts, whereas the swift looks mainly black, except for the 

 conspicuous white throat, a central streak of white on the breast, and 

 a white patch on each side of the rump. These white markings will 



