64 THE MIGRATIONS OF BIRDS 



laid in accordance with prevailing winds, as he con- 

 siders, from observations made in the West Indies, 

 that the birds tend to travel across the wind, which 

 thus shapes their line of direction. On this basis he 

 considers that, on leaving the coast from Labrador 

 south to Nova Scotia, the birds travel southeast 

 across prevailing southwesterly winds. This would 

 change to a southwest course when the northeast 

 trades were encountered at a point east of the 

 Bahamas, and so carry the birds to the northern 

 coast of South America. 



Some have considered that birds are sufficiently 

 observant to be able to guide a course by the sun by 

 day, or by the moon and the stars by night, a propo- 

 sition with certain merits, that has been set forth 

 recently by Mr. William Brewster in his posthumous 

 work on the Birds of the Lake Umbagog region of 

 Maine.^ Mr. Brewster considers it possible that 

 birds make note of the heavenly bodies and direct 

 their courses accordingly. This may be wholly 

 probable in some instances, but fails as a final, com- 

 plete explanation when we consider the regular 

 flights that are carried on during cloudy or rainy 

 weather, when the sun or the stars are obscured, 

 or the apparently marvellous way in which some 

 species travel without hesitation through dense fogs. 

 Though many become lost at such times, particu- 



^ Bull. Mus. Comp. Zobl. (June, 1924), Ixvi, 32, 2^. 



