60 Trans. Acad. Sci. of St. Louis 



we are permitted to judge the number of birds by count- 

 ing how many enter in one second and multiplying this 

 with the number of minutes. In this manner we arrived 

 at the prodigious number of 3,000. One of our surprises 

 was to see that after the birds had poured in for five min- 

 utes the number of wheeling, rushing, twittering birds 

 was the same as at the beginning, their ranks being con- 

 stantly filled by new arrivals and there was no let-up in 

 the rate of the influx until the last had dropped out of 

 sight at 6 :25 and darkness had fallen over the park. 



The chimney was built of brick in 1885, and according 

 to employes of the park has been used by the birds for 

 twenty years. It is 60 feet high, square and tapering 

 from six feet at the bottom to five feet at the top. Im- 

 mense as this structure is, it is sometimes not sufficiently 

 spacious to accommodate all the Swifts that come to roost, 

 and for such occasions an overflow roost has been estab- 

 lished in the chimney of the florist opposite the park on 

 Magnolia Avenue. Between 500 and 600 entered this 

 roost on October 14, but it had been given up on October 

 17. Between September 17 and October 15 we paid sev- 

 eral visits to the roost and found little change in behavior 

 and numbers except that on October 15 the first entered 

 at 5 :46, half an hour earlier than on September 17. 



October 15 was a fine day, partly cloudy with a temper- 

 ature of 73° and very light wind. When we arrived at 

 the roost at 4:35 only about 50 Swifts were dotting the 

 sky above the park disappearing for short times, appear- 

 ing again, but without any increase for an hour, and we 

 feared the bulk of the species had left us for good. But 

 during all this time the sight of a most beautiful illumina- 

 tion of the evening sky was enjoyed with utmost gratifi- 

 cation. As the clouds drifted slowly from west to east 

 they were colored by the setting sun, producing the most 

 delicate tints of rose upon the bluish gray and blackish 

 fn*ay background, deepening to fiery red from 5:20 to 

 5 :25, fading rapidly. At 5 :40 an increase in the number 



