232 SOME COMMON LAND-BIRDS. 



the nests built by other birds. The three species occurring 

 in the limits of the United States neither build nor care for 

 their young. This carelessness is the more notable because 

 the blackbirds, as a rule, build very respectable nests, and 

 their relatives, the orioles, are among the most famous weavers 

 in the world. Why is it that a single genus has entirely given 

 up the habit of nest building ? 



The female cow-bird lays an unending succession of eggs all 

 summer long in any nest that comes handiest, or sometimes 

 on the ground, as if not caring what became of them. Cow- 

 birds' eggs have been found in the nests of ninety different 

 species of North American birds, some in such strange places 

 as the eaves-swallow's high-hung cradle, the hole of the red- 

 headed woodpecker, and the long tunnel of the rock wren. 

 Usually she selects the nests of some smaller bird, and those 

 most commonly imposed upon are the phoebe, the song-spar- 

 row, the towhee, the indigo bunting, the oven-bird, and the 

 yellow-breasted chat. Often these contain several eggs of 

 the cow-bird and none of their rightful owner's. As many as 

 seven cow-bird's eggs have been found in one nest, though 

 it is not usual to find more than one. When this hatches, it 

 crowds out, smothers out, or starves out the young of the 

 rightful owner, and becomes sole occupant. It is estimated 

 that each female cow-bird 1 lays from eight to twelve eggs. 

 These are usually laid singly in nests that should contain 

 from four to five eggs of another bird. If all the cow-birds' 

 eggs hatched, each female cow-bird would be responsible for 

 starving from thirty to sixty little birds of our most benefi- 

 cial sorts. Perhaps it is fortunate that the males are in excess 

 of the females, or the destruction might be greater. 



1 Hudson estimates that the female Argentine cow-bird lays from sixty to a 

 hundred eggs in a season, and gives good reasons. 



