Nocturnal Flight of Birds 17 



Warblers, Finches, Woodpeckers, and Blackbirds. He was able to identify 

 with much certainty the characteristic undulating flight of the Goldfinch, and 

 the broad boat-shaped tail of the Purple Grackle. The flight of the birds noted 

 was apparently nearly at right angles to the field of observation, and they were 

 passing at the rate of 4^ per minute. As nearly as could be estimated their 

 height above the earth was between one and two miles. 



In the following year similar observations were made by Scott and Dr. J. A. 

 Allen, but the results were not as striking, only 13 birds passing in any quarter 

 of an hour. They were also apparently flying lower than on the first occasion. 



Some years later observations on nocturnal flight were taken up by Mr. Chap- 

 man, who spent three hours on the night of September 3, 1887, at Tenafly, New 

 Jersey. During this time 362 birds passed across the moon's face. Of these 233 

 were computed to be at a height of from 1500 to 15,100 feet, and curiously the 

 lowest birds seemed to be flying upward, as though they "had arisen in the imme- 

 diate neighborhood and were seeking the proper elevation at which to continue 

 their flight, but after that time the line of flight was parallel to the earth's 

 surface." He was able to identify positively only comparatively few species, 

 such as the Carolina Rail, Grackle, and a large Snipe. 



But perhaps the most satisfactory observations of all were those made also 

 by Chapman, who, in company with a number of ornithologists, spent the night 

 of September 26, 1891, at the Bartholdi Statue, New York. The weather proved 

 to be exceptionably favorable, being clear during the early and later portions of 

 the night, with an intermittent rain storm lasting for three hours between. As 

 early as eight o'clock the birds began to be seen and heard, but almost simul- 

 taneously with the beginning of the rain there occurred a very marked increase 

 in the number of birds seen about the light. They came singly, in troops and in 

 thousands, were visible for a moment and passed on into the darkness beyond. 

 "The birds chirped and called incessantly. Frequently, when few could be seen, 

 hundreds were heard passing in the darkness; the air was filled with the lisping 

 notes of Warblers, and the mellow whistle of Thrushes, and at no time during the 

 night was there perfect silence." 



Later recorded observations were made by Mr. O. G. Libby (Auk, XVI. 140), 

 who studied the nocturnal migrations at Madison, Wisconsin, in September, 

 1897. His first place of observation was a small' elevation in the vicinity of 

 three small lakes, where he undertook to make a record of the number of 

 bird calls heard. During the night a total of 3800 calls were recorded. The 

 number of calls varied greatly, sometimes running as high as two or three per 

 second and again falling to that number per minute. The largest number 

 counted was 936. 



From the nature of the data it was manifestly impossible to estimate the 

 number of birds represented by these calls, but the effect was impressive in the 

 extreme. He says: "Nothing but an actual experience of a similar nature can 

 adequately convey the impression produced by such observations. The air 

 seemed at times fairly alive with invisible birds as the calls rang out now faintly 

 and far away, now sharply and near at hand. All varieties of bird calls came 



