1304 U.S. NATIONAL MUSEUM BULLETIN 2 37 pakt 3 



laid, 1 on the day the third was laid, and 1 the day after the set was 

 completed. Of 3 females with sets of four eggs, 2 started on the day 

 the third egg was laid, and 1 on the day the set was completed; 3 

 females with sets of only two eggs all started the day they laid the 

 second. 



The average time of hatching for 10 sets of eggs was 12 to 12% days 

 after the first day of continuous incubation. One set hatched in 11 

 or 12 days, two in 14 days, the remainder at the average time. 



As might be expected from the individual variation in the beginning 

 of incubation, the eggs of one set may hatch all on the same day or 

 on two successive days. The longest intervals between first and last 

 hatchings of eggs in one set were somewhere between 7 and 15 hours 

 for a set of three eggs, and between 16 and 17 hours for a set of four. 

 The eggs in any one set do not necessarily hatch in the order in which 

 they were laid. 



Young. — The following account of Nuttall's sparrow applies also 

 to those populations of pugetensis and gambelii I have watched during 

 this phase of the breeding cycle. Where racial differences occur, 

 these are noted under the race in question. 



On the day the young hatch, the adults follow essentially the same 

 routine as during incubation. The female now alternates between 

 brooding the young and gathering food for herself and for them. 

 The behavior of the male is definitely affected and reflects awareness 

 of the event. He continues his patrol but spends more time near 

 the nest. He responds at once to the alarm notes of the female by 

 flying straight toward the nest and scolding. 



For at least the first 3 or 4 days the female bears almost the whole 

 burden of feeding the nestlings. I have seen her start to gather 

 insects within 2 hours after the young hatched, but have never seen 

 the male visit the nest until the 2nd or 3rd day after, and then rela- 

 tively rarely. At such times he never went directly to the nest, but 

 carried the food to a nearby perch and held it in his beak for as much 

 as an hour before feeding it to the young. 



The 6th day after hatching is the last on which I have found a 

 female brooding her young during the day; only rarely have I found 

 one sitting on the nest in the daytime after her young were 4 days 

 old. One female brooded her nestlings each night until the 8th day 

 after they hatched. 



Blanchard (1941) describes the nestling on the day of hatching as 



follows : 



The young bird just after hatching weighs a little over 2 grams. It has down 

 on the head, dorsum, wings and thighs; this dries in about two hours and stands 

 straight out from the body. The remnant of the yolk stalk is still visible, and the 

 viscera can be seen through the transparent skin of the abdomen. The bird 



