1174 U.S. NATIONAL MUSEUM BULLETIN 237 part 2 



the nest; 7-day-old nestlings often abandoned the nest after being 

 handled. Dawson and Evans (1957) report that "touching or jarring 

 the nest generally produced a gaping response in 5-day-old or younger 

 individuals whereas such a stimidus caused older birds to crouch low 

 and huddle in the nest." In the nests they studied 2 individual nest- 

 lings fledged at 8 days, 18 at 9 days, 20 at 10 days, 10 at 11 days, and 

 2 at 12 days for an average age at fledging of 9.85 days. The nestlings 

 increased from a mean weight of 1.7 gTams at hatching to about 10 

 grams at fledging. Walkinshaw (1944b) found several nestlings still 

 wet from hatching to weight 1.1 grams. 



Walkinshaw (1944b) reports that "YtTien only two or tlu-ee days old, 

 the young uttered a low zeee-zee-zee-zee call when they were fed. On 

 leaving the nest they immediately began to use a zip-ip-zip-ip-zip-ip 

 or chip-chip-chip call." 



He describes the nest-leaving as follows: "They hopped to the edge 

 of the nest and remained there for some time. Then they moved 

 gradually out into the branches of the nest tree. Sometimes one fell 

 to the ground, and it was then led by one of the adults, usually the 

 male, into a brushy area. By 10 days of age they could hop into the 

 lower branches of bushes, where they sometimes remained for long 

 periods on one perch. By 12 days of age they could fly a few feet, 

 and at 14 days of age they were capable of sustained flight." 



Plumage. — Dwight (1900) describes the juvenal plumage, which is 

 acquired by a complete juvenal molt, as foUows: "Above, wood-brown, 

 grayish on nape and rump, heavily streaked with duU black, faintly 

 tinged on scapularies and crown with chestnut. Wings and tail dull 

 black, rectrices and primaries ashy edged, the secondaries and ter- 

 tiaries chestnut edged, wing coverts and tertiaries terminally edged 

 with buff. lU-defined superciliary stripe, dull grayish white spotted 

 with black. Auriculars wood-brown. Dusky loral and postocular 

 streak. Below, white, streaked except on abdomen and crissum, with 

 dull black. Bill and feet pinkish buff, the former growing dusky and 

 the latter wood-brown with age." 



In juvenal plumage the chipping sparrow is most like the field 

 sparrow, but can be distinguished by the fact that it is "much more 

 heavily streaked, both above and below, than in the young field 

 sparrow, the dark markings being much sharper and more distinctily 

 blackish." (Sutton, 1935.) 



Sutton (1937) observed the plumage development and molts of a 

 young chipping sparrow, of precisely known age, from the time it left 

 the nest at 8 days of age until it was 8 weeks old. He summarizes the 

 changes as follows : 



