FAUNA OF THE ALEUTIAN ISLANDS AND ALASKA PENINSULA 223 



Troglodytes troglodytes petrophilus 



This wren is much like alascensis from the Pribilofs, but, with 

 comparable specimens, the upper parts appear to be somewhat 

 more rufescent and the under parts are definitely paler, or grayer. 

 The bill of petrophilus averages slightly longer than that of 

 alascensis, though the difference is small, and these two differ 

 from other Aleutian wrens in having somewhat shorter bills. 

 Measurements of the exposed culmen are as follows : 



petrophilus (11 males) 13 to 14.5 mm.; average, 13.9 mm. 



petrophilus (4 females) 13 to 14 mm.; average, 13.2 mm. 



alascensis (3 males) 13 to 13.5 mm. ; average, 13.3 mm. 



alascensis (7 females) 12 to 13.5 mm. ; average, 13 mm. 



This wren occurs on Unalaska, Amaknak, Unalga, and Akutan 

 Islands. One would expect to find it also on Umnak and Akun 

 Islands, but we do not have specimens from these two islands. 



Troglodytes troglodytes stevensoni 



This wren was described by Oberholser on the basis of speci- 

 mens from Amak and Amagat islands, near the west end of 

 Alaska Peninsula. It was described as being slightly less rufe- 

 scent than petrophilus and with a slightly longer bill and middle 

 toe. I found it very difficult to distinguish this form from 

 petrophilus by color, though the slightly longer bill was apparent 

 in the four adult specimens available. Most of the birds in the 

 series are young, and the material seems inadequate to determine 

 the status of this small group. The adult Aleutian wrens taken 

 during the nesting season are so irregular in condition of plumage 

 that a very extensive series should be at hand to adequately eval- 

 uate its taxonomic position. For this reason, I can not attempt 

 to ascertain whether these easternmost specimens of the Aleu- 

 tian chain show the slightest trend toward helleri, whose habitat 

 is far to the east, on Kodiak. 



Stevensoni is known from Amak and Amagat Islands, and it 

 can be expected to occur on adjacent parts of Alaska Peninsula 

 and on Unimak Island. 



Troglodytes troglodytes seguamensis 



Gabrielson and Lincoln (1951) described this form on the basis 

 of specimens from the islands of Seguam, Amukta, and Yunaska. 

 They commented that "This is the palest and grayest of all 

 the Aleutian races," and it appears, logically, to be an intermedi- 

 ate race between petrophilus to the east and tanagensis to the 



