1372 U.S. NATIONAL MUSEUM BULLETIN 237 paet 3 



ground before flying. Usually she remains quiet for about 30 seconds, 

 and then begins scolding with very fine, high-pitched chips, which are 

 gradually replaced with louder, metallic ones. The louder notes 

 attract the attention of the male, if he has not already been alerted, 

 and he begins chipping. During most of this performance, the birds 

 remain concealed in the vegetation. 



The reactions of the parent birds become more intense as incubation 

 progresses. The female is less inclined to leave the nest when a storm 

 or rain shower approaches and if flushed, she returns almost the 

 moment the intruder leaves the immediate area. Similar behavior 

 has been observed late in the evening. 



It is not known whether the male white-throat feeds the female 

 when she is on the nest. Observations at two nests suggest that he 

 may join the female at the nest on the day the eggs hatch. The 

 significance of this is not understood. 



The incubation period for the white-throated sparrow has been 

 given by Knight (1908), Burns (1915), Forbush and May (1939) and 

 Peters and Burleigh (1951) as 12 to 14 days. In the Algonquin Park 

 study Lowther estimated the incubation period to be 11 to 13 days. 



Young. — The young hatch almost naked, with only small tufts of 

 clove brown down on the dorsal tract of the head, body, and wings. 

 The eyes are sealed shut and open 3 or 4 days later. There is no 

 information on the development of feathers in the various tracts. By 

 the time the young leave the nest, the body and wings are fairly well 

 feathered, and the tail feathers are about one quarter to one third 

 erupted from their sheaths. Tufts of down remain on the ends of 

 some of the head and back feathers for as long as a week after the 

 birds have left the nest. 



By the fifth day after hatching, the young birds begin to show signs 

 of fear toward humans, suggesting that at this time they are totally 

 imprinted on the parent birds. Usually the female bird broods the 

 nestlings. Only once was a male seen brooding the young at Algon- 

 quin; he was flushed from the nest just before a thunderstorm broke. 



Observations on 12 nests in Algonquin Park in 1959 and 1960 

 indicate that the nestlings leave the nest between 7 and 12 days after 

 hatching, with 8 or 9 days being most common, and that they are 

 able to fly within 2 or 3 days after leaving the nest. The exact time 

 they become independent of parental feeding is not known. Both 

 parents feed the young in the nest, and continue to do so after they 

 have left it. When eventually the brood moves beyond the territorial 

 boundaries, only the female accompanies them, the male remaining 

 on his territory. 



Of the 28 nests Lowther found in Algonquin Park prior to June 8 

 in 1959 and 1960, 22 survived to hatching. The eggs in all 22 nests 



