to-day (16th) I examined the nest and found four young bitds. 
This would make the period of incubation only twelve days 
for even had the bird begun sitting when she laid her first 
egg, she could not have incubated the last more than twelve 
days unless she laid more than one egg a day, which seems 
highly improbable. 
The Red-eyed Vireo's nest was finished but empty 
when I found it on the evening of June 1st. There was one 
egg at 8 A. M. next day, and four when Gilbert again visited. 
Ball's Hill on June 5th. The Vireo has been sitting steadily 
ever since but when I last examined the nest at 7 A. M. 
to-day, her eggs although dark-colored were still unhatched. 
Assuming that she began incubating them on the 5th (when 
Gilbert found her on the nest) she has already devoted to 
the task nearly the same time which has sufficed the Robin 
to hatch her youngi She is a close sitter, allowing us to 
brush against the foliage which conceals the nest rather 
perfectly, without moving — but she will not permit us to 
quite touch her. 
