GAMBEL'S WHITE-CROWNED SPARROW 1329 



Egg laying extends from late May through mid-July in this race. 

 The earliest date for eggs is May 21 for two clutches I found at 

 College in 1957. The median date for the same locality for 13 

 clutches I found was May 23. At Mountain Village in 1950 the 

 median date was later, between June 2 and 3 for six clutches. 



Clutch size averages greater in the Gambel's sparrow than in 

 either nuttalli or pugetensis. The number of eggs per clutch ranges 

 from 3 to 6, with one record of 7 eggs in one nest. The average of 76 

 clutches is 4.58. The most common number of eggs per clutch is 5. 

 The percentages are as follows: three eggs per clutch 9.21 percent, 

 four eggs per clutch 32.9 percent, five eggs per clutch 50.0 percent, 

 six eggs per clutch 6.6 percent, and seven eggs per clutch (one record 

 only) 1.3 percent. The average clutch size by month is: May 4.71, 

 June 4.65, July 3.40 for 14, 57, and 5 clutches, respectively. I have 

 no evidence that Gambel's sparrows lay more than one clutch per 

 season if they successfully fledge one brood. 



As in pugetensis, clutch size in the Gambel's sparrow appears to 

 increase with latitude. Five sets of eggs taken between latitudes 

 51° and 55° N. average 4.20 eggs; 4 clutches collected between 56° N. 

 and 60° N. average 4.50; 32 clutches between 61° N. and 66° N. 

 average 4.56 eggs, and 27 clutches taken between 67° N. and 69° N. 

 average 4.74 eggs per clutch. 



Incubation. — I know the length of the incubation period for three 

 females of this race. Two at Mountain Village hatched their eggs 

 12 days after they started incubating. One at College hatched her 

 eggs 11 days after she began incubating. This is the only case in 

 any of the races I found where the incubation period was less than 12 

 days. One of these females began sitting the day she laid the fifth 

 and last egg of the clutch. The other two began sitting the day 

 they laid the fourth of five eggs. 



Young. — The nestling period in gambelii averages shorter than in 

 nuttalli or pugetensis. For 13 nestlings watched at Mountain Village, 

 the time spent in the nest ranged from 8 to 11 days, or an average of 

 9.6 days. For 15 nestlings watched at College, the time spent in 

 the nest ranged from 7 to 9 days, or an average of 8.4 days. 



Gambel's sparrow young become independent of their parents 

 at least by the time they are 28 days old. I trapped three young of a 

 pair at this age. In this, they do not differ significantly from the 

 Puget Sound sparrow young at Friday Harbor. 



Fall.— In 1957 I watched Gambel's sparrows before and during 

 fall migration at College, Alaska (lat. 64°49' N.). That same year, 

 Mrs. Priscilla Phillips (personal communication) watched the arrival 

 of Gambel's sparrows at Santa Barbara, Calif., some 2,400 air miles 

 away. Though observations at these two localities complement 



