NUTTALL'S WHITE-CROWNED SPARROW 1305 



breaths spasmodically, the entire body throbbing. It responds to jarring of the 

 nest by raising its head and waving it about unsteadily, the mouth wide open. 

 At first it holds this position only for a moment before its head drops forward 

 and the "egg position" is resumed. I can hear no sound even when the beak is 

 wide open. 



The following description of the development of behavior of the 

 nestling is based upon my observations and those of Richard C. Banks 

 (1959): On the day after hatching I could hear the nestling squeak 

 faintly. The earliest the bird can right itself is 2 days after hatching. 

 The eyes begin to open 3 days after hatching and by the 5th day they 

 are wide open. Reflexive grasping of the nest lining by the feet be- 

 gins about 4 days after hatching. On the 5th day after hatching a 

 new posture, crouching, is assumed. By the 7th day after hatching a 

 large number of nestlings give protest notes when handled. The 

 first concerted escape attempt occurs at 8}^ days after hatching. 



Banks (1959) describes the growth of the feathers in nestling NuttalFs 

 sparrows as follows: 



At hatching, dark spots representing feather papillae are visible beneath the 

 skin surface on the alar, humeral, dorsal, and coronal tracts of White-crowns. 

 External feather sheaths first appear when the birds are lYi to 3 days of age. 

 The first rupture of these sheaths occurs at age 53^ or 6 days. At 7 days of age, 

 the tips of the primary sheaths begin to break. Feathers of the anal circlet appear 

 without visible external sheaths. 



After an initial slow start, feather growth is rapid and constant. Primaries 

 grew at a maximum rate of 3.9 mm. per day; rectrices grew as much as 9 mm. 

 in 3 days. Although weight increases occurred only during daylight hours, feather 

 growth continued throughout the day. 



The young normally leave the nest when about 10 days old. For 

 23 nestlings the time spent in the nest varied from 9 to 1 1 days, or an 

 average of 10.1 days. Blanchard (1941) describes the subsequent 

 life of the fledglings as follows: 



The first few days after fledging, the young perch in the shrubbery near the nest. 

 They are usually so well concealed and respond so quickly to the warning tit 

 of the parents that it is impossible to see them. The male now shares about equally 

 with his mate the work of feeding the young. When the parents bring food or 

 come near them in foraging, the fledglings utter teez and flutter their wings. 



By the third to seventh day after fledging, the young of seven broods which I 

 followed had moved to clumps of shrubbery some distance away from the nest. 

 This must have involved crossing several yards of open grass — whether by hopping 

 or hying I do not know. I suspect by the former method, since my earliest records 

 of Might are for birds which had been out of the nest from seven to ten days. 



When the young of the first brood are about twenty days old, the male takes 

 over most of the task of feeding them. By this time the female has usually begun 

 to work on her second nest. When from twenty-five to thirty-one days old, the 

 fledglings forage for themselves but still beg food from the parents. The adults 

 continue to feed them a little longer but soon ignore their persistent teez and may 

 even chase or fight them. The oldest fledgling I have seen fed by a female was 

 thirty-two days old, the oldest fed by a male, thirty-five days. Once I saw a female 

 646-737— 6S— pt 3 5 



