Nesting Behavior of the Yellow Warbler. 61 



There was an unusual occurrence on July 8, when an ex- 

 creta sac was left in the nest during- two successive visits by 

 each of the parent birds, although on the third visit the fe- 

 male carried it away. This instance is the more extraordin- 

 ary, for there were times when one of the parent birds would 

 be making a feeding visit and upon seeing an excreta sac in 

 the nest, would promptly swallow the food so as to carry 

 away the excreta at once. 



While the nestlings were small, they were watched as far 

 as was possible to ascertain whether the excreta was always 

 taken from the same bird as fed. It was noted that this gen- 

 erally held true. Then after the young had been marked, 

 more complete records were taken. Out of a total of one 

 hundred and sixty-eight times, there were but five times re- 

 corded that the young" voiding the excreta was not the one 

 fed at that visit. 



The excreta was usuall}^ eaten by the parents until July 

 5 ; on this day it was carried away a little over half of the 

 time. And from then on, it was eaten only on eight occa- 

 sions. Table V shows the disposal of the excreta and the 

 total number of defecations. 



TABLE V. 



Showing by days the total number of excreta sacs, together witli 

 their disposal. 



Sex July 2 3 4 5 6 7 8 9 10 11 12 Totals 



Eaten m 4 7 6 1 18 



f 8 25 23 12 3 2 1 2^ 76 



Carried m 6 8 9 10 20 17 70 



f 1 4 12 2125 27 34 36 27 2 189 



Total 13 38 4134 34 49^45 34 38 27 2 363^ 



^ One of the sacs of excreta was but partly eaten. 



° On one trip the sex of the parent bird was not determined, and 

 also once not noted whether excreta was carried away or eaten. 



^ Eight times the excreta sac fell to the ground and was neither 

 carried away nor devoured by the parent birds, but are included 

 in the final total. 



Observations were taken as to what was done with the 

 excreta when carried away and it was seen that the parent 



