Olive-hacked Thrush at Summer Home. 131 



which prompts birds so universally to eat the ordure of the 

 young" for varying times in different nests. ^ 



This summer, 1 made a discovery that may possibly throw 

 some light on the question. When a Blue-Headed Vireo 

 family vacated their nest, I found in it two dried excrements. 

 The sacs had been in the nest so long that they were dis- 

 colored ; they were lost evidently when the gelatinous en- 

 casing sac was a conspicuous part of the excrement. The 

 sacs were full of the eggs of the rosy maple moth.'^ This 

 fact proves that during certain stages in the nest life, the 

 food of the nestling is but partially digested. Some of the 

 eggs were whole. Whether the eggs were fertile or not, I 

 was unable to find out but it is just possible that this universal 

 tendency of the birds to eat the excrement, is another of na- 

 ture's wise provisions for our further protection from our in- 

 sect foes. 



As already attested the female Olive-backed feeds the young 

 almost entirely by regurgitatin, sometimes as often as once in 

 four minutes. When the female returns from her rest peri- 

 ods, she brings fresh insects with her, and the male also 

 feeds the young regularly fresh insects as well as crushed 

 and mascerated food. At first, small, soft insects are admin- 

 istered, later, larger, tougher insects. 



I found the first two Thrushes in the nest at 11 :30, and 

 weig"hed and measured them a little after 12 :00 o'clock. 

 Each day the weights and measurements were taken as 

 nearly at this hour as possible. For days and days we had 

 a slight thunder shower at noon that interfered with work 

 a trifle. When I observed in the morning, it was t he 

 end of an observation day, and the afternoon was the begin- 

 ning of an observation day, in other words, I reckoned time 

 from the noon -that I found the two young Thrushes in the 

 nest. 



^ Home Life of Wild Birds. By Dr. Francis Hobart Herriclv. 

 Page 391. 



^ Kindly identified by Prof. Charles P. Alexander of (Cornell 

 University. 



