300 BULLETIN 17 6, UNITED STATES NATIONAL MUSEUM 



* * * The Swift takes a number of very rapid strokes, its wings 

 fairly twinkling through the air, and then sails with the long narrow 

 wings curved backward and slightly downward." 



Vaux's swift shares with its eastern relative the social habit of 

 roosting in chimneys in large numbers at certain seasons. Mr. Rath- 

 bun has described this very well in the following elaborate notes: 

 "About the middle of August the actions of this swift show the time 

 is near when it intends to leave the region for its winter home. Now 

 the social trait of this bird is much in evidence. For late in each 

 day the swifts begin to assemble in the vicinity of some hollow tree 

 of size, or some good-sized chimney not in use, within which they aim 

 to pass the night. W© have watched this action on the part of the 

 birds from its commencement to the close. In one case where a large, 

 tall chimney was used, 25 days elapsed from the time when first they 

 began to use it until the last of the swifts ceased to do so. The 

 swifts began to resort to the chimney about the middle of August, 

 and each evening thereafter for the next 10 days showed an increase 

 in their number until at least 500 made use of it. Then for 16 days 

 the number of birds steadily grew less until only three swifts entered 

 the chimney to pass the night, and after this for several days no more 

 were seen to use the place. 



"The swifts began to come to the locality where the chimney 

 stood an hour or two before sunset. Usually they flew about the 

 chimney or quite close to it. From time to time there were arrivals, 

 which mingled with those in flight, all forming a long and narrow 

 flock of flying swifts that swept around the top of the chimney, their 

 twittering so loud and ceaseless as to be heard some distance. At 

 times a few would leave the flock and enter the chimney, but the 

 constant arrival of others seemed to keep the flock entire. As they 

 circled some made feints to enter, and this appeared to be a sign 

 that soon an entrance would be made by all. Usually these actions 

 lasted for more than half an hour, but ceased when the twilight 

 reached a certain stage. For then the swifts would suddenly enter 

 their retreat, and while this act was taking place, it bore a likeness 

 to a long black rope one end of which dangled in the chimney's 

 mouth. 



"Each evening the performance was much the same, but sometimes 

 an incident would be connected with it. Once when the swifts were 

 racing, a pigeon hawk appeared and dashed at them. Instantly the 

 birds scattered, with the hawk in chase of one it had singled from the 

 flock, but as it made no capture it returned and perched for a short 

 time in a tree not far distant from the chimney. But when it left 

 the swifts at once returned in close formation, hung above the chim- 

 ney for an instant, and then appeared to fall therein. Not one 



