South American Cow-birds 317 



our European Cuckoo. The males exceed the females in 

 number, and the latter are polyandrous. Each female is 

 said to lay from eight to ten eggs, and Captain Bendire 

 believed that several days elapsed between the laying of 

 the eggs. " It is not likely," he says, " and this is very 

 fortunate indeed, that more than half of the eggs are 

 hatched, as some are dropped in old and abandoned nests, 

 or, when the female is hard pressed, even on the ground, 

 others in just completed nests in which the rightful owner 

 has not yet laid, who, seeing the parasitic egg in its nest, 

 either abandons it entirely, or constructs another over 

 the first, burying the strange egg among the building 

 materials. The same habit has been observed by Mr. 

 W. H. Hudson in some of the South American Cow-birds, 

 and he mentions an instance in which he examined a 

 bulky nest of the Yellow-browed Tyrant-bird (Sisopygis 

 icterophrys), and found, as he expected, some buried eggs 

 of the parasitic Molothrus underneath the superimposed 

 nest, but on breaking the three eggs, he f^und that two 

 were addled, but the third contained a perfectly developed 

 and hungry embryo of the parasitic bird, and it was evident 

 that the warmth engendered by the nest above it, and 

 doubtless also the heat of the sitting bird, had aided its 

 own vigorous constitution in keeping it alive. 



Whenever th.3 Cow-bird victimizes a foster-parent, it 

 seems to be its regular custom to peck holes in some of the 

 eggs of the latter, so that their undivided attention may be 

 bestowed upon the foundling which is in their midst. The 

 period of incubation seems also to be less in the case of the 

 Cow-bird's egg than in that of most Passerine birds, as it 

 only takes ten or eleven days to hatch out, so that when it 

 is placed among eggs of other birds already sat on, it comes 

 out of its shell about the same time, and eventually becomes 

 the sole occupant of the nest, not, as far as is known, by 

 ejecting the other nestlings as the young Cuckoo does, but 



