122 University of California Publications in Zoology. [Vou.5 
bark until it packed tightly enough to afford support for the nest 
proper. The bark strips extended down fully a foot in the 
cavity, and some of them protruded through the vertical slit 
which served the birds as an entrance. The main mass of the 
nest consisted of shredded, weathered inner bark strips of the 
willow, felted finest internally, where admixed with a few small 
down-feathers. This nest proper was six inches wide in the 
direction permitted by the space, and only one and three-fourths 
across the narrow way. The nest cavity was one and one-third 
by two and one-fourth inches, so the sitting parent probably 
always occupied one position diametrically. 
No nests with eges were found later than June 11, but young 
were found, yet unable to fly, until July 20. Two sets of eggs 
found on June 11, consisted of four and five eggs, respectively. 
Broods of young were of three to six individuals, one of the lat- 
ter number being noted on June 26. 
The ground color of the eggs is pure white. The markings 
are elongated in shape lengthwise of the egg. The brightest 
markings are burnt sienna, the tint varying from this towards 
vinaceous as the depth of the markings in the shell-substance in- 
creases. The darkest markings average one millimeter in di- 
ameter, while the vinaceous ones vary down to mere points. The 
markings are most crowded around the large ends of the ege- 
shells, and radiate from this pole in lesser numbers towards the 
opposite pole. The nine eggs are quite uniform in appearance, 
though certain ones are to be distinguished as more sparsely, more 
boldly, or more minutely marked. The markings on one set are 
not so dark as on the other, approaching pale hazel at darkest 
and ranging to vinaceous-cinnamon. 
In shape the eggs of the Sierra creeper vary from ovate to 
elliptical ovate. The two sets measure, in hundredths of an inch: 
.61X.45, 63.42, .61.44, .60.44 and 56.43, 57.44, 59x 
44, 55.48, 58.43. 
The twenty-two skins of this species secured agree in being 
slightly larger than birds from the Sierra Nevada, and several 
have the dorsal white streaks broader. In these respects they 
show a slight approach toward the race montana, of the Rocky 
Mountain region of the United States. 
