DUSKY, GRAY, AND SLATE-COLORED 349 



made outside the nest. Both sexes share in the fun of 

 nest-building, busily carrying short hair, featliers, and 

 wool, and staying inside long enough to settle a much 

 larger house. They work industri- 

 ously for five or six days, until it 

 seems as though at least a peck of 

 trash had been tucked into the old 

 oak tree. Then, after a day or so of 

 play, the mother settles down 

 to fourteen days of brooding 

 in the dark nest hole. In a 

 case which I recorded she 

 was fed by her mate at short 

 intervals during all this long 

 incubation, and many were 

 the worms 1 saw him carry to 

 her. He never entered the 

 nest without first calling from 

 outside, when she would an- 

 swer and often come up to 

 the door to be fed. We knew 

 at once when the young had 

 come out of the shells, for 

 his exaggerated anxiety and 

 comical airs of business told 

 his secret. A listening at the doorway further confirmed 

 this three days later. He now scolded at any approach to 

 the nest and tried to win our attention to himself, while 

 the female slipped in and out with food. My theory that 

 most young birds are fed by regurgitation at first was 



733. Plain Titmouse. 



^^BusUy -carrying shm-t hair, featherSf 

 and woot.^* 



