A DEAD BEAT. 235 



Among the cuckoos, the first stage of borrowing a nest seems 

 not to have been observed; but the second, of laying in the 

 nests of other birds of the same family, is not infrequent 

 among the American cuckoos ; and the third, of complete para- 

 sitism, though rare among the American, is habitual in the 

 European cuckoo, which neither builds its nest nor cares for 

 its eggs. It would seem that parasitism must be a habit Avhich 

 has been increasing among these birds, and that our American 

 cuckoos are yet in the earlier stages, while our cow-bird and 

 the European cuckoo have passed on to the extreme form of 

 the habit. But habits are not acquired by a perfectly regular 

 and imperceptible advance. There are always some birds that 

 are ahead of the rest and some that are behind in learning the 

 new ways ; even after the habit has become a settled one, there 

 are survivals of the older habit or reversions to it, just as in 

 forming a new habit there are anticipations of it by the most 

 progressive birds. Who knows then but some day sharp eyes 

 may yet discover an old-fashioned cow-bird, not yet educated 

 up to this end-of-the-century new-birdism, feeding her young 

 in a nest of her own building ; or perhaps may be able to prove 

 that our cuckoos have as yet just begun their career of para- 

 sitism, and, like the cow-bird, are degenerating into bird- 

 hoboes, and gradually but surely becoming bad bird-citizens. 



