•5 8 Dwight, Plumage Wear and Subspecies. f Jan. 



Thrush {Hylockhla ustitlata alma) which it is claimed differs 

 from swainsoni by its grayer coloration, a character that would 

 seem more likely to have been inherited from northern ancestors 

 than imposed by present "climatic conditions. I have compared 

 a good many breeding birds from Alaska with others from Eastern 

 Canada and the difference between them is very slight and not 

 easily made out. The Alaska birds average slightly grayer but I 

 have seen several Canadian specimens that are typical alma. 

 What the variation in the fresh plumage of ahnce. may be I do not 

 know, but swainsoni shows so great individual variation, that I 

 think it would be mere guesswork to call pale winter birds taken 

 in Texas, we will say, alma and dark ones swainsoni. Here again 

 I believe the validity of the subspecies turns on the comparison 

 of fresh plumages which are not at present available, and the same 

 thing may be said of the Juncos and the Horned Larks and a 

 dozen other species of birds whose limits of variation in fresh 

 plumage are quite unknown. Among the thousands of birds in 

 collections a very small percentage throw light upon this matter, 

 and until new plumages are thoroughly studied there is ample 

 justification for regarding many of the pallid races with suspicion. 

 To place them on a thoroughly scientific basis, eliminate the 

 direct effects of wear and the characters which remain will repre- 

 sent to a greater or lesser degree geographical variation. Unless 

 I am much mistaken subspecies will eventually be recognized by 

 better characters than those visible in breeding birds alone, and 

 will represent more thorough work than the mere matching of 

 shades of color or averaging of dimensions. The discovery of 

 new races will mean more work and less play. 



