NORTHERN BLACK SWIFT 267 



Referring to the summer movements of the swifts, about Seattle, 

 Wash., he writes (1925) : 



The Swifts that remain in this region undoubtedly nest far within the Cas- 

 cade range, and each morning from their chosen retreats make a trip to the 

 lowlands where they seem to stay most of the day. * * * 



By the middle of June, the Swifts instead of associating in such large num- 

 bers seemed to have separated into colonies of varying sizes, each of which, 

 during the summer months, appears to follow a certain more or less defined 

 route every day, which the birds used each morning when flying from their 

 mountain resort to the lower country, returning over it with equal regularity as 

 the evening drew near. 



These journeys have the appearance of being long excursions, but the wide 

 distances mean little to this Swift with a power of flight to which there seems 

 but little limitation. Tlie valley of the Middle Fork of the Suoqualmie River, 

 some thirty miles almost due east of Seattle, is one such route that we have 

 noticed the Swifts following; and here at various times during several sum- 

 mers we have watched the daily flight of a colony of these birds that numbered 

 nearly one hundred and fifty. 



In a valley of one of the mountain rivers, on an afternoon in June, 

 Mr. Rathbun observed a flight behavior, which he describes in his 

 notes as follows : "No swifts were seen until about 5 : 30 p. m., when 

 a few flew by widely scattered. At 6 : 30 p. m., more swifts began 

 to straggle past. While watching them, I noticed a dark, dense cloud 

 moving slowly toward where I stood. I expected to see some swifts 

 in company with it. I was not disappointed. There were about 50, 

 and it was of interest to see them gliding around in advance of and 

 below the cloud. By their actions it looked as if they were feeding, 

 arid all kept pace with the slow movement of the cloud. None of the 

 swifts were below 400 feet, some much higher. As the cloud passed 

 the swifts kept company with it ; and then followed an interval when 

 none were seen. Half an hour or so later another of the heavy clouds 

 rolled up from the west. Only a short distance in front of it were 

 more swifts circling, these soon followed by others gliding about 

 beneath the cloud. In this flight were at least 60 of the birds, and, 

 as in the first instance, they moved along with the cloud until losb 

 to our sight." 



M. P. Skinner has sent me the following notes on a flock of swifts 

 that he watched at the Vernal Falls in the Yosemite Valley : "After 

 circling once or twice around at the falls, they flew down the canyon 

 below for half a mile rvith great swiftness, then whirled in a circle 

 and came back. They repeated this over and over again. They kept 

 in the early morning shade as long as I watched them. Periods of 

 wing beating alternated with gliding on set wings, and both periods 

 varied very much in length." 



Ralph Hoffmann (1927) says : "The flight of the Black Swift is 

 amazingly swift; it includes sudden sharp turns, steep downward" 



