156 



Wild Birds 



The building records of these birds may be tabulated as 

 follows : 



BUILDING RECORD OF ROBIN. 



From the time of completion to the laying of the first egg 

 two days elapsed, and during this interval all was so quiet about 

 the premises I even feared that they had abandoned their nest; 

 but they probably continued to guard it, and certainly did after 

 the first egg was laid. 



According to our computation, 218 loads or increments went 

 into this building; it was wrought in about twenty -three work- 

 ing hours, and four fifths of the work was performed by the fe- 

 male. At the nest each bird worked alone and out of sight of the 

 other, so that the possibility of imitation was excluded. It is in- 

 teresting to see how the rate of building, starting with an average 

 of seventeen visits to the hour on the first day, gradually slowed 

 up to eight visits on the second day and to five on the third, 

 when a new habit was gradually developed, that of sitting 

 quietly in the nest for longer and longer intervals. Later these 

 resting periods become even longer, when the bird stays to lay 

 her eggs and finally to incubate them. 



Whenever instinct leads the way, and actions are often 



