1302 U.S. NATIONAL MUSEUM BULLETIN 237 part s 



1923) or "* * * pale greenish blue, varying to brownish, spotted with 

 cinnamon or reddish brown" (Gabrielson and Lincoln, 1959). The 

 first description is for a clutch taken at Alameda, California, and hence 

 nuttalli, the second of one collected in Humboldt County and therefore 

 pugetensis, the third of eggs of GambeFs sparrow. Davie (1883) 

 comments on a clutch assignable to oriantha collected at Hancock, 

 Colorado: "* * * the markings are much heavier and thicker near 

 the larger ends." 



Some egg measurements are as follows: For nuttalli, a clutch of 

 four eggs measured by Davie were .94 x .68 inch, .88 x .65 inch, 

 and two .88 x .64 inch. Dawson gives the average measurements of 

 70 eggs of pugetensis as 20.7 x 16 millimeters, the extremes being 18.5- 

 22.4 millimeters by 14.7-16.5 millimeters. For oriantha W. G. F. 

 Harris gives the average of 40 eggs as 21.1 by 15.8 millimeters, the 

 eggs showing the low extremes measuring 22.9 by 16.8, 19.8 by 16.3, 

 and 20.3 by 1J+.1 millimeters. For gambelii Harris gives the average 

 for 40 eggs as 21.5 by 15.5 millimeters, the eggs showing the four 

 extremes measuring 24.1 by 17.0, 18.5 by 14.7, and 22.4 by 14.2 

 millimeters. 



The limits of the egg-laying period for the four races are from early 

 March to late July, and the date when the first clutch of the season is 

 laid depends upon race and latitude. The number of eggs per clutch 

 varies from 2 to 6, with two exceptional cases of 7 eggs per clutch. 

 The average clutch size varies with race, latitude, the month in the 

 breeding season the clutch is laid, and the age of the female. The 

 eggs of one clutch are laid one each morning on successive days until 

 the clutch is complete. 



The rest of this section presents the data on eggs of NuttalTs 

 sparrow. The respects in which egg-laying in the other races differ 

 from nuttalli is discussed elsewhere. 



The first egg is laid from 1 to 7 days after the nest is completed (an 

 average of 3.6 days for 12 records), and from 4 to 9 days after the first 

 observed copulation. The egg-laying season in nuttalli begins in most 

 years in mid-March and finishes by late June. Extreme dates for 

 clutches are Mar. 3, 1936, for a clutch I found at Berkeley, and July 24, 

 1898, for one M. S. Ray found in the San Francisco Bay Region. 

 Median dates for first egg of first clutch laid at Berkeley for 5 years are 

 as follows: Mar. 22-23, 1934 for six clutches, Apr. 4, 1935 for six 

 clutches, Mar. 11, 1936 for seven clutches, Apr. 13, 1937 for nine 

 clutches, and Apr. 7, 1938 for five clutches. The contrast in the 

 median dates for the Berkeley popidation between 1936 and 1937 shows 

 how weather conditions (chiefly mean temperature) can influence the 

 time nesting starts in this race. This marked annual variation for the 

 same locality is characteristic of the resident NuttalPs sparrows, which 



