INTRODUCTION. xxi 



their nests as a rule ; the burrowing is effected by pick- 

 ing with the bill and scraping with the feet. 



Many birds are parasitic, getting their eggs hatched 

 and reared by others, the most familiar instance of this 

 being the European Cuckoo. Not more than half the 

 known Cuckoos have this habit, but it is found again 

 in the Honeyguides and in some of the American 

 Troupials, notably the well-known Cowbird {Molobrus 

 pecoris) of North America, and its southern allies. 



Polygamy is usually confined to the Game-Birds, 

 and in such cases the female undertakes the entire 

 charge of the eggs and young. Polyandry appears in 

 several cases where the male undertakes family duties, 

 as in the Tinamous. In the Rhea the instinct seems 

 to be in a fluctuating state in this respect. The male 

 fights his rivals and guards the hens, of which he will 

 secure several. Yet he sits on the eggs and cares for 

 the young, and the female in captivity will often pair 

 with another male. As a general rule, where the male 

 undertakes the sitting and rearing, the character of the 

 sexes is reversed, the female being bolder and more 

 pugnacious, and even larger and more brightly coloured, 

 though she is never so far superior to the male in appear- 

 ance as male birds often are to females. In a very 

 large number of cases the sexes of birds are practically 

 exactly ahke, as in the ordinary Pigeons. 



Close examination, however, generally shows that 

 the male is slightly larger and longer-headed and 

 billed in such cases. The New Zealand Huia {Hetera- 

 locha acutirostris), a black jay-like bird allied to Star- 

 lings, offers a very curious case, the male having a bill 

 much Hke a Woodpecker's, while the female's is long, 

 thin, and curved ; they hunt rotten wood for insects 

 in couples, the male pecking, and the female probing, 

 for prey. The great superiority of appearance in the 

 male is, of course, a familiar fact in many cases ; 

 it being so well known in the Fowl and Common 



