1110 U.S. NATIONAL MUSEUM BULLETIN 23 7 paht 2 



prospective summer territory inasmuch as he returned to the locality on November 

 8, 1935, where he was banded on January 30 of the same year and where he was 

 recaptured in early March; (2) that the female probably appeared on her breeding 

 ground after the male had established himself; (3) that nesting activities were 

 under way by March 24; (4) that one brood was hatched near the first of June, 

 another in late July, and the last in late August; (5) that the male was father to 

 three broods and the female was mother to the first and third and probably the 

 second broods * * *, 



Eggs. — The gray-headed junco lays from three to five shghtly 

 glossy eggs. They are usually ovate, although some may tend to 

 short ovate. The ground is white, or very pale bluish-white, speckled, 

 spotted, and occasionally blotched with "buffy brown," "sayal brown," 

 "pecan bro^vn," or "russet" \vith undermarkings of "pale mouse 

 gray." These spottings may be scattered over the entire surface, but 

 are usually concentrated toward the large end, frequently forming a 

 "wreath. The markings are often dull and somewhat clouded, and 

 tend more toward yellow-browns whereas both Junco hy emails and 

 Junco oreganus have red-brown spottings. Sometimes a set or a 

 single egg may be found that is plain bluish-white with only a few 

 specks so small that they are hardly visible. The measurements of 

 47 eggs average 19.9 by 15.2 millimeters; the eggs showing the four 

 extremes measure 22.0 by 15.8, 20.6 by 16.0, 18.7 by 15.0, and 19.3 

 by 14.1 millimeters. 



Young. — There appears to be no record of close observation of the 

 complete nesting cycle of the gray-headed junco. Incubation time 

 can be assumed to be 11 or 12 days, as given by Bergtold (1917b) for 

 the slate-colored junco. Miller (1938) notes that two eggs laid in 

 captivity by a "Point Pinos junco" (J. 0. pinosus) mated with a male 

 dorsalis hatched in 12 days. While determining the sex of an incubat- 

 ing bird is difficult, unless the bird is collected or the male is singing 

 nearby, a bird flushed from the nest is generally assumed to be a 

 female. Mearns (1890a), however, as noted above, says of dorsalis: 

 "The male parent flew from the nest," while it contained eggs. 



From his observations on caniceps near Boulder, Colo., N. F. 

 Hadley (MS.) ^vrites: 



The female alone incubates the eggs. The male will occasionally fly down to 

 the nest and feed her v/hile she incubates and then fly away, or both may fly 

 away together. The male sometimes remains at the nest edge while the female 

 flies off, but I never saw one enter the nest and assume an incubating position. 

 The female on the nest continually changes her position and turns the eggs, using 

 both her bill and feet for the purpose, commonly once every five to ten minutes. 



The male's arrival with food can often be foretold by the incubating female's 

 actions. Alerted by some sort of signal from the male, not always heard, she 

 perks up her head and turns it from side to side in anticipation. When ants or 

 other insects pass by within reach, she will reach out to grab them. She also 

 leaves the nest at intervals to feed herself. I observed one pair feeding together 

 on the floor of a lodgepole stand over 200 yards from the nest. The frequency 



