1120 U.S. NATIONAL MUSEUM BULLETIN 237 part 2 



and sometimes three pitches * * *," and the call resembles more the 

 "tsip" of the chipping sparrow. The gaits of the two differ notice- 

 ably also, for, as Peterson (1948b) says: "Fm*thermore, the Arizona 

 [Mexican] Junco creeps along in strange mouse-like fashion. * * * 

 whereas other jimcos habitually hop." According to L. N. Nichols 

 (1936) the Mexican junco "is said to have less the manners of a Junco 

 than of a Water Thrush," and Allan Brooks (1914) agrees that "it 

 walks daintily and deliberately over the floor of the forest like a tit- 

 lark or water-thrush, instead of the shuffling hop of the junco and 

 sparrows." 



Owing to the free interbreeding of the gray-headed and Oregon 

 j uncos where the breeding range of the former meets those oi J. 0. 

 thurberi and J. 0. mearnsi, birds of mixed plumage are numerous in 

 the overlapping ranges and occur commonly throughout the winter 

 range of caniceps. Many of these have the red back of caniceps with 

 the pinkish sides of mearnsi. In some individuals the red back is 

 diluted or mixed with yellowish, or the pink of the sides is spotty or 

 on only a few feathers. A few may have the dark head of thurberi or 

 the brown or yellowish back of the Oregons, with the gray sides of 

 caniceps. Variations are almost unlimited and most confusing to the 

 close observer. The mated female J. 0. thurberi and male J. c. caniceps 

 X J. c. mearnsi Miller (1935) collected at the meeting point of the 

 ranges of the three forms could certainly have produced puzzling 

 offspring ! 



Enemies. — The enemies of the gray-headed junco are presumably 

 those common to most small ground birds, but we have little definite 

 information on this subject. The eggs or young of only two of seven 

 nests I have observed until completion were taken by what I have 

 assumed were small mammals. Upon investigating an unusually 

 vigorous scolding by a pair of gray-heads at 9,500 feet in Colorado, in 

 mid-August, I found a fledgling junco a day or two out of the nest in 

 the jaws of a large garter snake and released it, apparently unharmed. 



One of the young of the campus nest, at Boulder, Colo., previously 

 mentioned, was said by O. A. Knorr (pers. comm.) to have been taken 

 by a screech owl nesting nearby. R. G. Beidleman (1957) mentions 

 long-eared owls which "evidently preyed on the juncos" on a winter 

 population study area in Colorado ponderosa pine, where four species 

 of juncos, including caniceps, were present. Miss Oppie Reames 

 (pers. comm.) reports a pygmy owl (Glaucidium gnoma) eating an 

 Oregon junco in southern Colorado in late October, undoubtedly from 

 a mixed flock with a high percentage of gray-heads. Denis Gale (MS.) 

 presumed predation by the northern shrike in northern Colorado. 

 His notes state for Oct. 17, 1889: "Saw a Northern Shrike * * *. 

 Evidently has crossed the range in the wake of Juncoes [sic] and was 



