EASTERN FIELD SPARROW 1225 



female on the nest, usually large larvae. When the female leaves the 

 nest to feed, the male joins her and they go to the feeding grounds to- 

 gether. While she feeds he remains very alert, and gives a low m arn- 

 ing "Zeee-zeee-zeee" if an enemy appears, especially a hawk. 



In 74 sets of marked eggs I found the incubation period ranged 

 from 10.5 to 17 days and averaged 11.6 days. In 44 of the 74 clutches 

 the last egg hatched 11 days after it was laid. 



Young. — On Aug. 7, 1938 an egg hatched while I held it in my hand. 

 Pushing with its head, neck, feet, and mngs, the young bird finally 

 split the egg near the larger end where the shell had been incised by the 

 egg tooth. It took several minutes to emerge because it rested for a 

 few moments between each attempt. The empty shell weighed 0.3 

 gram. I placed the fledgling in the nest with a sibling that had 

 hatched an hour earlier, and it curled up in the bottom. When I 

 touched the nest it responded immediately by raising its head and 

 opening its mouth. From my notes I (1939c) described it as follows: 



The color of the skin and legs is pinkish, the bill pinkish, grayed near the tomia. 

 The lining of the mouth is yellowish, pinker near the side. The small egg tooth, 

 near the tip of the maxilla, is white and soon disappears. The eyes show in large 

 gray areas beneath the skin and are closed. No suggestions of feather tracts are 

 visible. 



The weight of the young bird which hatched in my hand was 1.5 grams. His 

 wing measured from the bend to the tip, 6 mm. The tarsus measured 5 mm. and 

 the culmcn 3 mm. * * * 



By the second day the primaries showed in dark lines through the skin. The 

 dorsal feather tracts were discernible. The ventral regions showed merely as 

 lines but were easily seen on the third day. The occipital regions were dotted 

 black at two and one-half days. 



Newborn nestlings varied in weight from 0.9 to 1.5 grams and 

 averaged 1.62 grams on the day of hatching. On the 2nd day they 

 weighed 3.67 grams, on the 3d day 5.43 grams, on the 4th 5.43, on 

 the 5th 7.31, 6th 8.61, 7th 9.64, 8th 10.2, and 9th 10.1 grams. They 

 attained the full adult weight of 13 grams on the 13th day. 



The female stays on the nest and broods the young at night until 

 they are 6 days old; females were found on the nest over 6-day young 

 at night only about 50 percent of the time, and over 7-day young only 

 25 percent. She also broods the young a great deal diu-ing the day- 

 time during early nestling life, and especially during periods of incle- 

 ment weather. This decreases steadily as the young feather out, and 

 ceases entirely by the 6th day. 



Both parents feed the 3"oung and tend to nest sanitation. As the 

 fledglings mature they are fed more and more frequently. At a nest 

 A\4th tliree young under 3 days old, the parents brought food 23 times 

 (the female 18 times, the male 5) and removed excreta 3 times dm-ing 

 312 minutes of observation. When the young were 5 and 6 days old 



