SAN PEDRO CHICKADEE 363 



plumaged birds, but it is a character that tends to be lost even when the feathers 

 become only slightly worn. 



Together with this darkening there is restriction in the area covered by the 

 one conspicuous white marking on this bird, the superciliary stripe, which marking 

 extends forward in fresh plumage to nearly or quite meet its fellow on the fore- 

 head. The white on the head of atratus is not only less in area occupied, but it 

 is shallower; and birds in breeding plumage, when it is reduced or effaced by 

 wear, come to bear a curious resemblance about the head to Pcnthcsics atricapillus. 



They gave the range of this form, "so far as known, only the main 

 plateau of the Sierra San Pedro Alartir" ; and they state that it "ad- 

 heres closely to the coniferous belt of the Transition and Canadian life- 

 zones." The 1931 Check-list extends its range to include the Sierra 

 Juarez, of northern Lower California. 



It probably does not differ materially in its habits from other 

 races of the species. 



The measurements of 6 eggs average 16.5 by 12.6 millimeters; the 

 eggs showing the four extremes measure 16.8 by 12.7, 16.5 by 13.0, 

 and 16.2 by 11.7 millimeters. 



PARUS GAMBELI GAMBELI Ridgway 

 MOUNTAIN CHICKADEE 



Plate 57 

 HABITS 



The species Pants gambeli occupies a wide territory in western North 

 America, from British Columbia to Lower California and from the 

 Rocjcy Mountain region westward to the Pacific coast region, in all 

 suitable mountain ranges. The type race, the subject of this sketch, is 

 confined to the Rocky Mountain region, from Wyoming and Montana 

 southward to Arizona, New Mexico, and central western Texas. 



It is well named the mountain chickadee, for, during the breeding 

 season at least and for much of the remainder of the year its favorite 

 haunts are the coniferous forests of the mountains, from 6,000 up to 

 11,000 feet, but mainly at the higher levels, 8,000 to 10,000 feet. Below 

 the coniferous forests it is largely or wholly replaced by the long-tailed 

 chickadee. 



In fall the mountain chickadees, with their young, range up to timber- 

 line or even beyond ; in fall and during winter they often range down 

 to the foothills and valleys, where they are sometimes seen together 

 with the long-tailed chickadees in the fringes of cottonwoods and willows 

 along the streams. 



Mrs. Bailey (1928) says that, in New Mexico, "they may be met 



