372 THE FUR SEALS OF THE PEIBILOF ISLANDS. 



Hawaiian islauds. Migrating birds evidently have a power of keeping a straight 

 course for very long distances, a sense of direction, as it were, which enables or allows 

 them to fly at certain periods for a certain time, the starting and arriving places being 

 positive factors as well as the distance between, thus insuring an arrival — winds and 

 other influences permitting — within a certain time near some objective point, the 

 exact location of which can be ascertained by the ordinary powers of observation. 

 As we in ourselves combine in a marvelous degree certain attributes or powers, purely 

 educational ones, unknown to, or only in an embryonic stage in our ancestors, so 

 birds, migrating first from necessity over short distances, have during the lapse of 

 countless ages, as necessity enforced, developed a sense of direction which is practi- 

 cally unknown among mammals and is consequently difficult to be imagined and 

 understood by ourselves. This accounts for the great loss when migratory species, 

 like the Pacific salmon and the European migratory quail, are transplanted to 

 localities geographically opposite that to which their ancestors had for ages been 

 accustomed to. 



It must not be understood that I am wedded to the idea that land connection 

 must have been straight and continuous between the Aleutian and Hawaiian groups. 

 It would seem more probable that these ancient connective land areas existed 

 between these points, but fronting on the American and Asiatic continents, respec- 

 tively. The descendants of our ancient migrating birds possibly have simply gradu- 

 ally straightened out the originally somewhat perhaps crooked course. . In other 

 words, the lines of migration to day are somewhat different from the ancient lines 

 because of the tendency of natural selection to weed out gradually those individuals 

 or groups of individuals not adapting themselves to the altering physical condi- 

 tions and availing themselves of the direct, less dangerous, and shortest route 

 between the starting and objective points. Our knowledge of Pacific migration is 

 still in its infancy, and this brief chapter may suggest further investigation. 



Synopsis of Pritilof Mrda. 



Swimmers 39 



Waders 15 



Birds of prey 5 



Perchers 10 



Total species 69 



Total families 21 



Total geiiora 56 



