1530 U.S. NATIONAL MUSEUM BULLETIN 23 7 part 3 



and the earliest nest was found on Apr. 12, 1918, a year with an un- 

 usually warm spring. A like date is given for Washington by W. L. 

 Dawson and J. H. Bowles (1909). At these dates few other species 

 are nesting in the song sparrow's habitat. 



Nesting. — -Dawson and Bowles (1909) describe a pattern of nest 

 placement that prevails for many other races: First nests are usually 

 built on the ground under cover of vegetation, and elevated nests (up 

 to 20 feet high) become commoner as the season advances. Occa- 

 sional ground nests may be found at any date, e.g., on Aug. 3, in 

 Washington. On the other hand, Rust (1919) gives an interesting 

 portrayal of a different kind of seasonal change in nest location, 

 with heights tending to move downward from elevated positions to 

 the ground. At Fernan Lake, Idaho, the onset of breeding coincided 

 with high water levels, and early nests invariably were in spirea 

 shrubs and willows whose bases were partly submerged. Receding 

 water in mid-May exposed clumps of sedge, which were then used for 

 some nest sites, although shrubs and willows also continued to be 

 selected throughout the season. J. C. Merrill (1898) never found a 

 nest on the ground, and most were in bushes growing in water. 

 Dawson and Bowles and also Merrill describe clumps of debris stranded 

 in willows by flood water as common nest sites. 



J. C. Merrill (1898) writes that nests near Ft. Sherman, Idaho, 

 were "unusually large for a song sparrow" and were built largely of 

 dead leaves and strips of cottonwood bark, deeply cupped and with 

 finer materials for the linings. Rust found sedge the most used 

 plant material and reported that nests built later in the season were 

 more compact and less precariously wedged in forks and supports; 

 horsehair was a common lining. 



Eggs. — The measurements of 40 eggs average 20.1 by 15.0 milli- 

 meters; the eggs showing the four extremes measure 22. If. by 15.5, 

 20.8 by 16.3, 18.3 by 15.2, and 19.3 by 13.7 millimeters. 



Rust (1919) found 4-egg clutches more numerous than 5-egg clutches 

 at Fernan Lake, Idaho. Near Ft. Sherman, Idaho, Merrill (1898) re- 

 ports 5 as the common size of the first clutch, 3 or 4 as the usual later 

 sizes. 



Incubation, young.— The incubation period is set by Dawson and 

 Bowles (1909) and by Rust (1919) at 12 days, but Rust's nestling 

 period, 14 to 16 days, seems remarkably long in view of the periods 

 known for euphonia, 10 days, and melodia, 10 to 14 days. Dawson 

 and Bowies' statement that young can "fly" when 12 days old should 

 be compared with Mrs. Nice's finding that 17 days is the age at 

 which young of euphonia commonly begin to fly. Fledglings remain 

 in dense underbrush and sedge until fairly strong on the wing. 



