1 88 Bird -Lore 



A nest of the Wood Thrush was found on June 29 containing two eggs of 

 the Cowbird and none of the Thrush. What had become of the Thrush eggs, 

 if any had been laid, could not be determined. On July 2, one egg hatched and 

 on July 3 the other was gone. On July 10, the young Cowbird, fairly well 

 feathered, left the nest, constituting the entire brood of one of our most bene- 

 ficial birds. 



A second nest of the Wood Thrush, containing two eggs of the' owner, was 

 found on July 14. On my next visit to this nest on July 17, one of the Thrush 

 eggs had been picked, evidently by a bird, and thrown from the nest. Two 

 Cowbird eggs had been deposited in its place. This, again, is circumstantial 

 evidence that the Cowbird destroys the eggs of other birds. By July 28 all 

 three eggs had hatched. All three birds thrived well until August 5, when one 

 of the young Cowbirds was found dead, from some unknown cause, in the 

 nest. It was removed by its foster parents on the same day. The other two 

 birds, one Thrush and one Cowbird, continued to thrive and left the nest on 

 August 8. Although the Cowbird was a little more developed than the Thrush, 

 both probably survived and reached maturity. 



There is every reason to believe that the Sparrows suffer heavily from the 

 Cowbird. Of fourteen nests observed, ten of the Field Sparrow and four of 

 the Song Sparrow, all contained one or more eggs of the Cowbird except three 

 nests of the Field Sparrow. In two of these three nests the young were raised 

 unmolested. The eggs of the third nest were destroyed before the period of 

 incubation began and the nest was deserted. The fourth nest, found June 29, 

 contained one egg of the Sparrow and two of the Cowbird. By June 30 one 

 more Cowbird egg had been deposited. The period of incubation now began. 

 On July 12 one of the Cowbird eggs was found missing and the Sparrow egg 

 was found on the ground near the nest with the young Sparrow almost ready 

 to emerge, apparently a little prematurely, from the shell. I replaced it in the 

 nest, but found it dead, the Cowbirds dead in the shells, and the nest deserted 

 the next day. So many tragedies of this character are found among the birds 

 that one wonders how we have as many feathered friends as we have. 



A fifth nest, found June 30, contained one egg of the Field Sparrow and one 

 of the Cowbird. Persons who had observed this nest, previously, informed 

 me that one Cowbird had been hatched here but that it had disappeared from 

 the nest a few days after hatching. On July i, my sixth nest of the Field 

 Sparrow, containing four eggs of the rightful owner and one of the parasite 

 was found. By the 5th all the eggs had hatched, two Sparrows and the Cow- 

 bird having appeared as early as July 3. It is interesting to note that the 

 Cowbird had one or two days the start of at least two of the Sparrows; also 

 that one Sparrow had been crowded out before July 7 and another before 

 July 12, when two Sparrows and the Cowbird left the nest. The seventh 

 eighth, and ninth nests of this species were found during the second half of 

 July and each contained a Cowbird egg or eggshell. The previous history is 



