354 BULLETIN 19 7, UNITED STATES NATIONAL MUSEUM 



The remaining three eggs hatched during the following two days. 

 "It will be noted that the first, second, and third young birds were 

 hatched in fourteen days after the laying of the first, second, and 

 third eggs, respectively. The time required for the incubation of 

 the fourth egg lies somewhere between thirteen days, three hours, 

 twenty-eight minutes and thirteen days, eleven hours, sixteen minutes 

 [between times of examination]. If all the eggs were warmed alike 

 when a bird was incubating, and if the several eggs required equal 

 amounts of incubation to cause hatching, it would appear that incu- 

 bation began as soon as the first egg was laid, but that it was more 

 broken and ineffective between the laying of the third and the fourth 

 eggs than at other times." 



He gives the following brief outline of the chief events at the nest : 



June 15. First egg laid. 



June 18. Fourth (last) egg laid. 



June 2U. First egg hatched. 



July 1. Third and fourth eggs hatched. 



July 3. First cries of young heard. 



July 12. Three oldest nestlings left nest. 



July 13. Fourth nestling left nest. 



July 14. Last observation of nestlings (two only). 



On July 6: "Between 12.51 p. m. and 2.35 p. m. the young were 

 fed at 12.52, l.lT, 1.20, 1.28, 1.39, 1.46, 1.52 (twice), 1.51 (twice), 2.20, 

 2.27 and 2.29, a total of thirteen feedings in one hour and forty-four 

 minutes. I have recorded two feedings at 1.52 p. m. because at that 

 time I saw the two parent Vireos stand on opposite sides of the nest 

 and both feed the young at once. At 1.54 both birds were in sight 

 near the nest at once and they fed the young in quick succession. At 

 1.20 and again at 1.52 one of the old birds, after feeding the yomig, 

 removed excrement from the nest and flew away with it. The young 

 birds were brooded from 12.52 to 1.16, from 1.28 to 1.36, from 1.39 to 

 1.46, and from 2.29 to 2.35, when I departed for a few minutes." 



For an early morning feeding period, he made the following rec- 

 ord: "Between 4.00 a. m. and 7.00 a. m. the young were fed at the 

 following times : 4.06, 4.17, 4.29, 4.31, 4.38, 4.39, 4.40, 4.42, 4.45, 4.48, 

 4.49, 4.50, 4.52, 4.55, 4.56 (twice), 5.30, 5.54, 5.55, 6.00, 6.02, 6.03, 6.04, 

 6.05, 6.09, 6.12, 6.15, 6.18 (twice), 6.21, 6.28, 6.30 (twice), 6.32, 6.35, 

 and 6.51, a total of thirty-six feedings, or nine for each young bird, in 

 the first three hours of morning activity. * * * Between 4.05 and 

 4.57 there were sixteen feedings, between 4.57 and 5.53 there was one 

 feeding only, and between 5.53, and 6.53 there were nineteen feedings. 

 It will be observed that the feedings exhibit a marked periodicity, as 

 though the young were given regular meals, with intervals of com- 

 parative rest." He noted other evidences of periodicity at other times, 

 and saw some evidence that the parents were not satisfying their own 

 hunger during the periods of rest. "Food which I saw the adult Phil- 



