TREE SPARROW 1149 



Both parents shared the task of feeding their young, at first equally, 

 later with the heavier load falling on the male. During the first few 

 days the nestlings were fed only three or four times an hour; thereafter, 

 an average of 16 feedings per hour was maintained, at intervals ranging 

 from 1 to 10 minutes between visits. 



During the early days the female brooded the young 74 percent of 

 the time. Periods averaged about 8 minutes, occasionally as long as 

 % hour, with intervals of only 3 to 8 minutes away from the nest. 

 After a few days, feeding occupied a greater proportion of her time, 

 and brooding periods were short and infrequent, rarely exceeding 3 

 minutes. At 6}^ days she was on 20 percent of the time during the 

 very early morning, but not at all later in the day, though the female 

 on nest IX was flushed from her nest on the 8th day. At night most 

 of the birds remained with their young the full term of 9M days. 



At the age of 2 days the nestlings were sufficiently developed to 

 stretch for food. From this time until fear was acquired, they 

 responded with outstretched necks and gaping mouths to any motion. 

 At 4 days the eyes were half open, and at the end of 5 were wide open, 

 after which their responses were somewhat more discriminating. 



They emitted no sound until the age of 5 days, and even at 8 days 

 they usually simply raised their heads to accept what their parents 

 brought. 



Fear was acquired abruptly between 7}i and 8 days, correlating 

 perfectly with the development of physical independence. In my 

 daily rounds I had found them at first unalarmed by my presence 

 and quiet during weighing. At nest III, where three banded young 

 had hatched K day before the other two, weighings were made just 

 before these birds were 8 and 7K days old, respectively. By keeping 

 them in a box they were retained long enough to weigh. As soon as 

 they were returned to their nest, the three older birds scrambled off 

 into the bushes, while the other two remained serenely their full term 

 of 9}^ days in the nest. 



During the 9th day in the nest the young became quite active, 

 shifting and stretching frequently, and greeting the parent bringing 

 food by outstretched necks, fluttering wings, and noisy clamors. The 

 undisturbed normal method of departure was observed at nest I. 

 Arriving at the nest in the early afternoon of July 8, I found three of 

 the brood already gone and the youngest, banded with a green thread 

 at the time of hatching, sitting alone in the nest. The female bird 

 came soon thereafter with food, which Green accepted quietly without 

 moving to follow. His reaction was quite different when the male 

 came. Immediately the young bird hopped past the proffered food 

 and out onto the open tundra, peeping vigorously, sprawUng and 

 stumbling over the uneven ground 1 or 2 feet behind his father, who 



