NESTS AND NEST-BUILDING IN BIRDS 367 



at 4.56 A. M., dropped down quietly and was joined by the male 

 in her search after food. Incubation, as in other instances 

 noted, began with gradually lengthening periods of sitting 

 until the appearance of the third egg, when it was regularly 

 established. 



Bluebirds. — While watching bluebirds carrying nest materials 

 to a box, 47 visits were made by one or both birds in the course 

 of 70 minutes, or with an average of one visit every i^ minutes. 

 Male and female were at the nest box together 22 times during 

 the interval, and the male made two visits alone. The usual 

 proceedings at these functions were as follows: The female 

 leading but closely followed by the male, flew to the top of the 

 box with her load of straws or dead grass held crosswise in bill, 

 entered and spent from a few seconds to a minute inside, peered 

 out and was off; the male, atop the box, would warble while 

 his mate was at work inside. Now and again he would look 

 into the hole or even enter and when the female left he followed 

 her quickly awa}^ At other times he would drop and shake 

 his wings, warbling all the while, as an invitation to the copu- 

 latory act, and would pursue his mate, if she were coy. Once only 

 was the male seen to bring a straw, and this caught at the en- 

 trance and was dropped, but more than once he entered the 

 box and carried a straw away. Once he awaited a full minute 

 inside, and until his mate returned with a fresh load. 



Twice the male bluebird brought an insect to the nest-box, 

 but it was not destined for his mate, and on one of these occa- 

 sions he clung to the entrance, like a bird bringing food to its 

 young, flying to and fro with it, shifting it about and finally 

 swallowing it himself. His chief office in the building process 

 was evidently that of guardian, but some of his acts which have 

 just been described suggest an imperfect development of the 

 building instinct, as well as a premature rise of the instinct 

 to feed the young. This bringing of food to the nest while the 

 work of construction is still under way seems to be perfectly 

 paralleled by the behavior of the male robin already described 

 (see p. 346). 



Woodpeckers, Chickadees, Kingfishers and Swallows. — Among 

 birds which excavate in wood the flicker and the red-headed 

 woodpecker are typical, working solely with their powerful 

 bills, which are used as picks. We cannot describe the process 



