1134 U.S. NATIONAL MUSEUM BULLETIN 237 paRT 2 



number of features which characterized the original pioneering popu- 

 lation. 



Relatively few ornithologists have seen Baird's junco in its natural 

 habitat, and even fewer have written about it. Much of the in- 

 formation in this report is taken from unpublished field notes of 

 Chester C. Lamb, who collected in the mountains of the Cape region 

 of Baja California in the winter of 1928 and the summer of 1929. 



Description. — ^Back and scapulars cinnamon brown, becoming buffy 

 brown on rump. Sides cinnamon, the color extending onto the breast 

 and sometimes meeting in a band across the breast. The cinnamon 

 fades with wear, becoming more yellowish. Lores blackish. Top 

 and sides of head and hindneck uniform light gray, the nape often 

 tinged with buff, at least in unworn plumage. Throat and upper 

 breast pale mouse gray, lower breast, abdomen and under tail coverts 

 white. Tail with outer two feathers partly, the outer often com- 

 pletely white, the third sometimes with a white spot. Iris yellow; 

 lower mandible yellow, upper mandible brown. Wing and tail 

 short, bill and feet moderately large, proportionately. 



Sexual dimorphism is limited to size and tail pattern, the female 

 being slightly smaller and averaging somewhat less white in the tail 

 (Miller, 1941b; Ridgway, 1901.) 



In Juvenal plumage this is the least heavily streaked junco (R. R. 

 Graber, 1955). 



Habitat. — Nelson (1921) characterized this bird as an inhabitant of 

 the Upper Sonoran Life Zone of the Cape region of Baja California. 

 According to Miller (1941b), it is one of the few juncos that breed 

 under zonal conditions lower than Transition. Frazer found it 

 inhabiting the pine and oak woods (Brewster, 1902), Miller (1941b) 

 amphfied the description of the habitat: "The region inhabitated is 

 forested predominantly vnih oak {Quercus devia), also with pinon 

 (Pinus cembroides) and madrono (Arbutus penninsularis) , and with 

 cottonwoods {Populus monticola) in the canyons." He further states 

 that "The natm-e of the region compares most closely * * * with the 

 Upper Sonoran oak belt of Arizona * * *." 



Belding (1883) found this species very common over 3,000 feet 

 elevation, and Miller (1941b) reports that most specimens have been 

 taken above 4,000 feet. Only a single bu'd has been taken as low 

 as 1,800 feet, at El Triunfo (Brewster, 1902). 



Habits. — Belding (1883), when reporting the capture of the third 

 and fourth specimens of this bird, said that "Nothing worthy of note in 

 connection with its habits was noticed." Brewster reported (1902) 

 that like most juncos they were tame and familiar, and that "they 

 often came into a shed where Mr. Frazer prepared his specimens, and 



