no. 3637 HERMIT THRUSH — ALDRICH 23 



Winters in Mexico (Sonora, Chihuahua, Guerero, Michoacan, 

 Morelos, Vera Cruz), south to Guatemala (Hacienda Chancol). 



Populations breeding in northwestern Montana, extreme south- 

 eastern British Columbia, and southwestern Alberta that have been 

 referred to sequoiensis by various authors, including Ridgway (1907), 

 Rand (1948), and Phillips (1962), probably are better considered as 

 intermediates between the large auduboni, to which race it is assigned, 

 and smaller races to the west, north, and east. Migrant specimens 

 from this region very likely are responsible for some of the more 

 eastern literature records of "sequoiensis," which race they resemble 

 superficially. 



As McCabe and McCabe (1932) pointed out, there is a tendency 

 for specimens with largest measurements to be from the southern 

 and middle Rocky Mountain area. For that reason, these authors, 

 as well as other investigators, recognized the distinctness of a Great 

 Basin race named "polionota" by Grinnell (1918) on the basis of 

 breeding birds taken in the White Mountains in central eastern 

 California. In the present study, I was unable with any degree of 

 certainty to sort out specimens on the basis of either size or color as 

 belonging to either a Great Basin or a Rocky Mountain race. Larger 

 and smaller as well as more grayish and more rufescent specimens 

 seemed completely intermingled even at the type-locality of polionota 

 in the White Mountains. If segregation into discrete breeding popula- 

 tions with different combinations of morphological characters exists, 

 it must be quite local and possibly correlated with local ecological 

 differences of the sort reported for hermit thrushes in Colorado by 

 Packard (1945) or as postulated for nighthawks by Selander (1954). 

 Such segregation was not apparent in the information furnished by 

 specimens examined in the present study; therefore, I am taking the 

 course followed by Phillips (1962) and considering polionota a synonym 

 of auduboni and applying that name to the entire Rocky Mountain- 

 Great Basin complex of large, pale hermit thrushes. 



7. Cascade hermit thrush: Catharus guttatus oromelus (Ober- 

 holser).— Medium shade, most grayish, Olive. Small: cf 1 (24 speci- 

 mens), wing 89.5-94.5 (91.6), tail 58-73 (68.0), culmen 11.5-14.5 

 (13.2), tarsus 26.5-31.5 (27.8), midtoe 15-18 (16.8); 9 (16 specimens), 

 wing 86-96 (88.9), tail 62-74 (66. 5), culmen 12-13.5 (13.1), tarsus 

 25.5-29 (27.1), midtoe 15.5-18 (16.8). 



Longer wing and shorter bill, darker and more grayish than slevini; 

 longer wing and bill, shorter tarsus, and more grayish than guttatus; 

 shorter tarsus, paler and more grayish than nanus; paler than vac- 

 cinius; shorter wing, darker and more grayish than sequoiensis and 

 euborius. 



