65 [Vol. xliii. 



unfortunately I had an accident and lost' two eggs from one 

 of them. Possibly the set of two (one of which was nearly 

 fresh) might eventually have been a three clutch, but un- 

 fortunately, too, the two Dove's eggs substituted in their 

 stead (and upon which the bird continued to sit) were 

 destroyed by vermin before the clutch was complete — or at 

 least any more eggs were laid. 



The birds were very shy indeed, and I was obliged to 

 exercise the greatest caution in approaching the nest in 

 order to identify the sitting bird before and as it left the 

 nest. Under no circumstances were any of the parent birds 

 in evidence during one's stay in the vicinity where breeding, 

 or after flushing the sitting bird. 



Referring to the eggs of 



COWBIRDS, 



Case No. 3 embraces the few eggs of the Cowbird 

 {Molothrus ater) with their respective fosterers I collected 

 in Ottawa, Canada, during my short stay there in May-Jun e 

 1919. The habits and eggs of tiiis species are well known, 

 and the specimens shown demonstrate very little variation, 

 though I have been given to understand that one of the 

 fosterers {Turdus migratorius) is not often victimized. With 

 regard to set No. 3 — two eggs of Song-Sparrow (Melospka 

 melodia) and one of Cowbird — there had apparently been a 

 severe scuffle between the Cowbird and the Song-Sparrows 

 in the immediate vicinity of the nest, the surroundings being 

 greatly disturbed and the nest subsequently abandoned. 

 I found this nest with the two eggs the day before, or the 

 same day perhaps, the Cowbird visited it. 



A noteworthy feature of this exhibit is the fact that two 

 female Song-Sparrows were occupying and laying in the 

 nest victimized by the Cowbird (No. 1), and that, having 

 lost their first home, they apparently together built a second 

 one, and laid therein four and two eggs respectively, while 

 surely the same Cowbird inserted her egg in the new nest ! 

 I had no opportunity of observing whether this species of 

 Cowbird destroyed or removed any eggs of the fosterers when 

 visiting the nests, so cannot say why both clutches of Song- 



