WEST 



and also bear a great deal on the rates at which they can or do 

 adjust to lowering temperatures. We talk about feather tracts, 

 and apteria, but I invite you to trap a Snow Bunting in late May 

 and rip all its contour feathers off. In other words, rip the feathers 

 off the pterylae, that is, the feather tracts. What will you have 

 left? You will have a body which is covered with a dense down 

 which covers the apteria. 



I have prepared finches from high latitudes and low latitudes, 

 and there is a striking trend. The lower latitude finches are 

 genuinely naked on their apteria, but the high latitude ones which 

 I have examined, the Golden Crowned Sparrow, the Lapland Long- 

 spur, and the Snow Bunding, are not. This must be a relevant con- 

 sideration to those interspecific differences on Dr. West's graphs 

 which seem puzzling. 



Another little detail which is perhaps a little more esoteric 

 is this; in larger passerines like the Steller's Jay, there is a 

 highly modified, stiff, hair- like feather, which is distributed 

 over the body. What is this for?Iam not sure that I have an answer 

 to what it is for, and I have not said anything about this in print 

 because there is such a depressingly large European literature 

 on plumage that I have not gone through it yet to see if somebody 

 has said something on the matter. But these stiff, hair-like feathers, 

 distributed over the body on a large passerine which has a very lax 

 and dense plumage, could increase the efficiency of spacing of the 

 plumage when the bird expands it and contracts it; and the presence 

 or absence of these hair- like feathers must be another little detail 

 that has to be plugged into these considerations of why Dr. West's 

 curves deviate as they do. 



WEST: What is the distribution of those?Are these filoplumes? 



PITELKA; Yes, filoplumes. They are regularly distributed 

 among the contour feathers. 



WEST: How about on the smaller birds, sparrows? 



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