MIGRA TION 563 



consists chiefly of the abortive or unsuccessful attempts at its 

 accomplishment, when birds are checked in their course, and being- 

 unable to proceed present themselves to our sight and hearing. If 

 this be so, the aid of "land-bridges" and river- valleys, the importance 

 of which is so strongly pressed by certain writers (mostly theorizers) 

 becomes insignificant. 



Now that birds can and do fly at elevations far beyond those 

 which most people are accustomed to think possible, Ave have some 

 indication. Mr. J. Tennant states {Stray Feathers, iii. p. 419) that 

 at Eoorkee on the 23rd Sept. 1875, while looking through a 

 telescope at the sun, he saw birds, apparently Kites, frequently 

 pass over its face, some of which were in focus with the sun itself 

 and must therefore have been several miles high, while the nearest 

 must have been quite a mile above the earth's surface. These 

 birds indeed were only soaring, on the look-out for prey, and not 

 migrating ; but a stronger case in point is the curious and valuable 

 observation recorded by Mr. W. E. D. Scott (Bull. Nuttall Orn. 

 CM, vi. pp. 97-100) when on the night of the 19th Oct. 1880, 

 he saw through an astronomical telescope, at Princeton, in New 

 Jersey, great numbers of birds passing aci'oss the face of the moon.^ 

 Computation shewed that these birds, which were on their autumnal 

 Migration, must have been travelling at heights varying from a 

 mile to two miles. Some time later, 16 th April 1881, the same 

 gentleman, in company with Mr. Allen, made some further observa- 

 tions {torn. cif. p. 188) at the same place; but on this occasion the 

 birds seen — Swallows, and on their northward joui^ney — were flying 

 comparatively low. They were also much less numerous, for only 

 13 passed in three-quarters of an hour, whereas on the former 

 occasion the average was 4 '5 per minute. Again Mr. F. M. 

 Chapman (Auk, 1888, pp. 37-39), also in New Jersey, watching 

 for nearly three hours on the evening of the 3rd Sept. 1887, saw 

 in like manner 262 birds cross the moon's face. Of these 233 

 were computed to be at a height of from 1500 to 15,100 feet; 

 but an especially remarkable thing is that the lowest birds Avere 

 " flying upward," as if they had risen from the immediate neigh- 

 bourhood and "were seeking the proper elevation at which to 

 continue their flight." ^ 



' " Most of the birds were the smaller land-birds, among which were plainly 

 recognized "Warblers, Finches, Woodpeckers and Blackbirds [Icteridee] . . . 

 Among the Finches I would particularly mention Chrysomitris tristis, which 

 has a very characteristic flight ; and the Blackbirds were conspicuous by the 

 peculiar shape of the tail, from which characteristic I feel most positive in my 

 identification of Quiscahis purpureus. " 



2 Among the bii'ds recognized on this occasion were 5 Carolina Rails. 

 of which 3 are computed to have been between the limits of 1900 and 10,200 

 feet, one between 2000 and 11,000, and one between 2600 and 13,500. 



r/. cM'^i^^ 



