A Second Season of Bluebird Tenants 



65 



also to obtain the proportion of time for the first and second broods, in order 

 to discover whether there is any adaptation of sitting periods to temperature. 



In this case, at least, the eggs were kept quite warm enough, and they hatched 

 at the end of two weeks, on Thursday, May 9. 



It had been six weeks now since the Bluebirds had first come to the shelf, 

 and, on the basis of the acquaintance with human neighbors which had been 

 gained the year before, there grew up an increasing familiarity with the back- 

 ground of a living-room and its human occupant. Their interest in this side of 

 their environment was, it must be confessed, purely a practical one, — it repre- 

 sented to them a commissary department with its dispensing quarter-master, 

 a source of supplies most welcome through a late, inclement spring. They 

 quickly learned the times at which they might look for an issuance of rations, 

 and so weather-wise did they become in signs that the raising of the sash or even 

 the stirring of the curtain drew them quickly to the shelf in eager expectation. 



As soon as there were seven mouths to feed, instead of two, there entered 

 in a more compelling force than hunger to overcome their fear. Before the little 

 ones were a week old, both birds, though still a little nervous, were feeding 

 from my hand at the open window, and during the second week they grew quite 

 fearless. If the worms were missing on the shelf, they spied the dishes in the 

 room, and soon they established a regular habit of flying in to help themselves. 



During the preceding season the mother-bird had seemed to bear the chief 

 burden of providing food and keeping the nest clean, but this year several watches 

 confirmed the impression that the male was equally active. The removal of 

 the excretal sacs was performed apparently with no regularity. During an hour's 

 watching, on one particular day, not a single sac was carried out. On the next 

 day, during a period of equal length, each parent once removed one. In another 



FEMALE BLUEBIRD FEEDING \(JU_\G. JUNE _i 



