34o THE STRUCTURE AND LIFE OF BIRDS chap. 



order of birds ; it is found in various stages of develop- 

 ment in the different species of the American Molothrus, 

 a bird allied to our Starlings. One South American 

 species {M. bonariensis) always lay their eggs in other 

 birds' nests, and never sit upon them themselves, but 

 the number of eggs laid in one nest is so great that it 

 is impossible all can be hatched. They sometimes lay 

 in old forsaken nests, or in a nest of the year where in- 

 cubation has already begun, or before the building is 

 finished, so that their eggs are covered by the thick 

 lining and never hatch. Many are dropped upon the 

 ground. The parents, too, will often peck holes in 

 numbers of their own eggs. Sometimes several 

 together set to work to build a nest for themselves, 

 but it is clumsily constructed, and, as far as is known, 

 is never made use of. Another species {Molothrus 

 rufoaxillaris) is also parasitic and apparently not so 

 foolish as the last mentioned, though not so accom- 

 plished a parasite as the Cuckoo. Another South 

 American species {Molothrus badius) is probably never 

 parasitic. But they sometimes go to the length of 

 seizing another bird's nest and building their own 

 upon the top of it. All these interesting facts we 

 owe to Mr. Hudson, who has carefully observed the 

 two South American birds that have the cuckoo 

 habit. 



In North America there is a Molothrus which never 

 lays more than one egg in one nest. 



In this genus, then, we see the instinct in its various 

 stages of development. Molothrus badius is a pirate 

 and not a parasite. M. bonariensis is foolishly prodi- 

 gal of its eggs. . M. rufoaxillaris shows a greater 



