166 



THE OOLOGIS1 



A few days later I investigated the 

 nest and found the bird still setting 

 on two of her own and two robins' 

 eggs never having laid any more 

 eggs; thus apparently showing that 

 the bird had some control over lay- 

 ing and had found that she had all 

 the eggs that she could cover. 



I again looked up my bird and 

 found two young birds of both spec- 

 ies, but the robins were a very thin 

 looking pair of birds. Three days 

 after this the birds were found dead. 

 Now in my mind the kingbird was 

 not able to feed them in the right 

 way and not that she was able to tell 

 that they were not of her own kind. 

 For if she could have told this' how 

 is it that she could not tell blue from 



brown spots on a white background. 



Besides the kingbird I tried chang- 

 ing eggs with two warblers; two 

 closely allied species. 



On June 18th I found the nest of 

 a black and white warbler (miniotil- 

 ta varia) with four fresh eggs as 

 shown in the accompaning picture. 

 Near this nest I found another nest 

 belonging to a pair of yellow warb- 

 lers (dendroica aestiva) which also 

 contained four fresh eggs. After 

 photographing the nest of the form- 

 er I took the eggs and replaced them 

 with the yellow warblers and then 

 stepped back to watch the affect. 



In a few moment sthe bird came 

 back, went deliberately to the nest 

 looked at the eggs hopped in, and- 



