152 Wild Birds 



turning movements were repeated, and thus the work of addi- 

 tion, subtraction, arrangement, and re-arrangement would go 

 on for hours, with serial repetition, and often with needless 

 expenditure of energy. Since, however, more was eventually 

 gained than lost, a stable foundation was gradually reared. 



On the first day I watched the progress of building for two 

 hours and thirteen minutes, during which thirty loads of material 

 were delivered by the two birds. In the first half-hour of this 

 period I recognized the female only, who came eight times to 

 the nest-site at intervals of from two to six minutes. Then 

 after a lull of full half an hour the male suddenly appeared, at 

 a few minutes before six o'clock. Twenty-one visits followed 

 at intervals of from one to nine minutes, during the last eighteen 

 of which the cock was positively identified. The last stroke of 

 the day's work was performed by the male at 7.07 P.M., when 

 it was growing dark, and he disappeared. After over four hours 

 of such industrious labor it was truly surprising to find how little 

 had been accomplished ; only a slight basis for the proper nest 

 had been laid, for with all of those turning and molding move- 

 ments so faithfully practiced, no plastic material had yet ap- 

 peared, and no true nest-form was visible. Could one want 

 better proof of the instinctive character of such actions? 



On the second day my record began at 5.20 in the morning, 

 and closed at 4.30 in the afternoon. The actual work of the 

 builders, however, was probably resumed at dawn, for when 

 at more than three hours thereafter at seven o'clock the nest 

 was examined, thin walls had arisen, and the proper nest-form 

 was determined. 



The building instinct in the male seemed to have been com- 

 pletely satisfied, for while he guarded the premises his mate 

 carried the work to completion. From neighboring trees he 

 watched her labors, sounded the customary signals, and gave 

 chase to casual visitors. 



At seven o'clock in the morning of this day, or after eight 

 hours of constructive work, mud began to appear among the 

 building materials. Hitherto the only earth used was that which 

 accidentally clung to the roots of the dead grass and weeds in- 



