no. 3637 HERMIT THRUSH — ALDRICH 7 



In color the greatest variation occurs in the Pacific Northwest. 

 The most darkly colored birds appear on Vancouver and the Queen 

 Charlotte Islands off the coast of British Columbia and the palest in 

 the interior of that province as well as the vicinity of the California 

 coast. The extreme in grayness is reached by populations in northern 

 Idaho and central southern British Columbia, and one of the most 

 reddish occurs on the Queen Charlotte Islands. All of these extremes 

 in color are found in the smaller winged group of hermit thrushes 

 (fig. 4). 



U5) (16) 



Figure 3. — Male tarus lengths of subspecies of Catharus guttatus, showing ranges (vertical 

 lines), means (horizontal), and two standard errors on either side of the means (rectangles). 

 (Numbers in parens = sample sizes. Numbers at bottom = 1, slevini; 2, oromelus; 3, vac- 

 cinius; 4, sequoiensis; 5, nanus; 6, guttaus; 7, euborius; 8, auduboni; 9,faxoni; 10, crym - 

 philus.) 



In the north, the transition from the small-winged Pacific coastal 

 populations to the medium-sized eastern birds occurs almost immedi- 

 ately after leaving the coast. Examples from interior Alaska, Yukon, 

 and interior northern British Columbia are larger and paler than 

 the coastal birds. From there eastward there is a change to darker 

 coloration with more rufescent upper parts and flanks, and to rela- 

 tively long legs. Transition in these characters occurs in western 

 Alberta. Birds from south-central Mackenzie (Great Slave Lake), 

 northeastern Alberta, and Saskatchewan east to the Atlantic sea- 

 board are relatively uniformly colored on upper parts and flanks. 

 The only distinct geographical trend in coloration of this thrush in 



