Life History of the Protfionotary Warbler. 31' 



Cobleigh, certainly must have been a double set. I can^ 

 think of no warbler that lays a corresponding number 

 of eggs. Mr. B. F. Bolt, of Peoria, 111., found a double 

 nest a number of years ago, the lower half containing 

 seven eggs, and the upper five. I am therefore quite 

 positive that two females will lay their eggs in the same 

 cavity, and that one pair of birds will deprive another 

 of their nesting site, and build another nest over that 

 of the original owner, in localities wherein nesting 

 sites are few. I have never noticed but one published* 

 account of such a procedure on the part of this bird. 

 Mr. O. C. Poling, who found double nests and sets of 

 the prothonotary warbler near Quincy, 111., says:* 



"It is also characteristic of this warbler to remain? 

 close about the nest at all times to avoid being deprived 

 of its home by some neighboring pair, for there are 

 more birds than nesting places in the localities searched. 



"On several occasions a hole would contain a nest and 

 fresh eggs, with still another nest built on top of it, also- 

 containing eggs, thus showing that some pair had driven- 

 off the first occupants. Several of these two-story nests^ 

 which I brought home with me got somewhat crushed 

 in packing, and the eggs were found broken within them. 



"Still another nest was found, in which two females 

 had laid, containing nine eggs which were of two differ- 

 ent types and piled up on top of each other. Both 

 females were near and they appeared quarrelsome during 

 the time I watched them." 



Another interesting feature connected with the nesting 

 of the prothonotary warbler is the imposition of the 

 cowbird. It is not universally known or believed that 

 this parasite will enter a cavity to deposit her ^^'^ or 

 eggs ; but it is not unusual to find one or more eggs of 

 the cowbird in a prothonotary's nest. Mr. R. M. Barnes 

 informs me that he has in his possession sets as follows: 

 two eggs of the warbler and three of the cowbird ; three of 

 the warbler and two of the cowbird ; four of the warbler 



♦Ornithologist and Oologist. Vol. XV.. p. 92. 



