184 3 Vol. XX1 
DESCRIPTION OF A TWENTY-YEAR SERIES OF EGGS 
OF THE SIERRA JUNCO 
By MILTON S. RAY 
WITH FOUR PHOTOGRAPHS BY OLUF J. HEINEMANN 
HE SERIES of eggs of the Sierra Junco (Junco oreganus thurbert) in the 
Woodland Heights Museum of Analytical Oology (San Francisco) con- 
sists of exactly seventy-five sets. These have been collected during the 
period from 1900 to 1919 or an average of about four sets a year. The sets 
taken were specially selected to show variation and constitute only a fractional 
part of the large number noted afield. 
In the arrangement of the following text, a systematic plan for egg de- 
scription is proposed in place of the incomplete, rambling and often rather 
vague descriptions of Oliver Davie and various other writers. The color-plate 
numbers refer to Ridgway’s Color Standards and Color Nomenclature, 1912. 
Notwithstanding the abundance of material in the museum or that which I 
have inspected afield, it is quite possible that other types of coloration in the 
eggs of this bird still remain to be described. 
Junco oreganus thurberi Anthony 
SIERRA JUNCO 
Synonyms.—Thurber Junco; Western Snowbird. 
Description.—Cf. Ridgway, Birds of North and Middle America, part 1, 1901, p. 287. 
Breeding Range.—Cf..Grinnell, Pacific Coast Avifauna no. 11, p. 120. 
Eggs.—Usually 4, sometimes 3, occasionally 5; also authentic set of 1. 
Size (in inches).—Average set (no. 23), .78x.60 .78x.59 .77x.61 .77x.61 
Small set (no. 47). .69x.49 .73x.51 .73x.51 .74x.52 
Small set (no. 61), .67x.54 .68x.54 .69x.54 .71x.55 
Large set (no. 20), .96x.57 .91x.57 .90x.57 
Shape.—Usually ovate or rounded ovate, sometimes short ovate, rarely ene ovate. 
Texture.—Fine. 
Surface.—A slight, very slight, or scarcely perceptible, gloss. 
Coloration.— 3 
1. Ground color white, faintly tinged with lichen-green (Ridgway, pl. xxxII=), 
spotted and blotched or splashed with hazel (pl. xIv), chestnut (pl. 11), and 
light vinaceous gray (pl. L). This is the usual coloration of the eggs of this 
junco. [Four eggs of set no. 15.] 
2. Ground color white, faintly tinged with lichen- -green (pl. xxxlII), heavily 
blotched and splashed, principally around the greater end, with hazel and cin- 
namon rufous (pl. xiv). [Egg of set no. 48.] 
3. Ground color white, faintly tinged with lichen-green (pl. xxxiII), spotted and 
lightly blotched, principally around the major end, with chestnut (pl. 1), vin- 
aceous drab (pl. xiv) and light vinaceous gray (pl. L). This specimen thus 
shows three distinct colors of markings. [Egg in set 12.] 
4. Ground color pale olive buff (pl. xL), spotted and splashed, principally in a 
heavy wreath around the larger end, with hazel (pl. xiv) and light vinace- 
ous-gray (pl. L). [Egg in set 74.] 
5. Ground color white faintly tinged with lichen-green (pl. xxxllI) roughly 
wreathed around the greater end with spots, splashes and scrawls of hazel — 
(pl. xiv) and light seal brown (pl. xxxIx), and with scattered spots of light — 
vinaceous-gray (pl. L). [Egg in set 56.] 
6. Ground color very pale lichen-green (pl. xxx), spotted and blotched (some — 
eggs very finely spotted and dotted), almost entirely in a wreath around the 
greater end, with light vinaceous-gray (pl. L) and aniline black (pl L). This 
is a very distinct and rather uncommon type. [Egg in set 33.] ; 
