38 The Migrations of Birds 



sounding out of the darkness that evening. The harsh squawk of a water bird 

 would be followed by the musical chink of the Bobolink. The fine, shrill notes 

 of the smaller Sparrows and Warblers were heard only close at hand, but the 

 louder ones came from all along the line, east and west. More than once an 

 entire flock, distinct by the variety of their calls, came into range and passed out 

 of hearing, keeping up their regular formation with the precision of a rapidly 

 moving but orderly body of horsemen. The great space of air above swarmed 

 with life. Singly or in groups, large and small, or more seldom in a great throng 

 the hurrying myriads pressed southward." 



The second station chosen by Mr. Libby was the Washburn Observatory, 

 where for three nights he watched the birds passing across the face of the moon. 

 During the three nights a total of 583 birds were counted, the largest number in 

 any fifteen-minute period being 45. Considerable diversity in the direction of 

 flight was noted. Thus up to ten o'clock the prevailing direction was south, but 

 after this time the diversity increased, until it reached its maximum between 

 twelve and two o'clock, when eight principal points of the compass were repre- 

 sented by numbers varying from 3 to 28. However, two thirds of the number 

 were still maintaining a southerly direction. 



Libby attempted to estimate roughly the total number of birds that passed 

 his point of observation during the three nights, but as he well says, "when one 

 recalls the relatively small size of the moon's surface as compared to its path from 

 east to west, within the range of vision," the difficulty becomes evident. As nearly 

 as could be made out, about 9000 birds were passing per hour, or a grand total 

 of 168,000. 



The rate of speed at which birds travel during the migrations, and also at 

 other times, has been made the subject of observation, although the results, as 

 might be expected from the confusing elements which must enter into such an 

 inquiry, are far from complete or satisfactory. If the speed often attained by 

 powerful and swift-flying species, such as Ducks, Geese, Swallows, etc., could be 

 maintained, it is obvious that the time occupied in migrations would be incon- 

 siderable. But, as will be shown later, the maximum speed appears to be rarely 

 or never realized at this time. 



Frank Forrester records 90 miles an hour for Ducks, as nojed by telegraph 

 from point to point, and an Albatross has been known to cover 3150 miles in 

 12 days. The actual distance flown by the latter bird was probably at least 

 twice as great, for they rarely fly far in a straight line. 



Some years ago Griffitt made some observations (recorded in The Field, 

 Feb. 19, 1887) in a closed gallery on the speed attained by "blue-rock" Pigeons 

 and English Pheasants and Partridges. The two first mentioned flew at the rate 

 of only 32.8 miles per hour, while the Partridge made but 28.4 miles, and these 

 rates were all considerably in excess of what they made in the open. The Carrier 

 Pigeon is a rather fast flying bird, yet the average speed is not very great. Thus 

 the average made in 18 matches (The Field, Jan. 22, 1887) was only 36 English 

 miles an hour, although in two of these trials a speed of about 55 miles was 

 maintained for 4 successive hours. In this country the average racing speed is 



