NOCTURNAL MIGRATION 65 



larly where puzzled by lights, others move without 

 difficulty. Mr. Brewster cites the ease with which 

 common terns return to their nesting-ground on 

 Muskegat Island through the densest fog, and such 

 phenomena are of common occurrence with the auk- 

 lets and murres of Alaskan waters, as these birds 

 drive directly for their island rookeries, without any 

 apparent hesitation, through the thickest weather 

 imaginable. In fact, the courses that they take are 

 often serviceable to sailors bewildered by fogs as 

 they indicate the direction of land. 



As a basis for consideration of the problem of how 

 birds find their way, it will be profitable first to con- 

 sider the case of the homing pigeon, and the little 

 that is definitely known of the method of its homing 

 activity aside from the fact that it is capable of re- 

 turning to its cote without great loss of time from 

 distances up to 1,000 miles. Those interested in the 

 sport of racing pigeons recognize individual ability 

 among their birds, and develop strains rated high 

 for the number of birds produced that are able to 

 compete successfully in distance flights. Birds that 

 are to be used in races each year are put through a 

 regular course of training that involves flights, first 

 of a few miles, and then others of increasingly 

 greater distance. One fancier thus regularly flew his 

 birds over courses of 9, 18, ;^;^, 45 and 66 miles, after 

 which the distance was increased to 100, 200, 400, 



