104 CHARLES DARWIN 



female in the season, then there must be as many nests as 

 females, and each cock bird will have its fair share of the 

 labour of incubation; and that during a period when the 

 females probably could not sit, from not having finished 

 laying. 16 I have before mentioned the great numbers of 

 huachos, or deserted eggs ; so that in one day's hunting 

 twenty were found in this state. It appears odd that so 

 many should be wasted. Does it not arise from the difficulty 

 of several females associating together, and finding a male 

 ready to undertake the office of incubation ? It is evident 

 that there must at first be some degree of association be- 

 tween at least two females ; otherwise the eggs would remain 

 scattered over the wide plain, at distances far too great to 

 allow of the male collecting them into one nest : some au- 

 thors have believed that the scattered eggs were deposited 

 for the young birds to feed on. This can hardly be the case 

 in America, because the huachos, although often found 

 addled and putrid, are generally whole. 



When at the Rio Negro in Northern Patagonia, I re- 

 peatedly heard the Gauchos talking of a very rare bird which 

 they called Avestruz Petise. They described it as being less 

 than the common ostrich (which is there abundant), but 

 with a very close general resemblance. They said its colour 

 was dark and mottled, and that its legs were shorter, and 

 feathered lower down than those of the common ostrich. 

 It is more easily caught by the bolas than the other species. 

 The few inhabitants who had seen both kinds, affirmed they 

 could distinguish them apart from a long distance. The 

 eggs of the small species appeared, however, more generally 

 known; and it was remarked, with surprise, that they were 

 very little less than those of the Rhea, but of a slightly differ- 

 ent form, and with a tinge of pale blue. This species occurs 

 most rarely on the plains bordering the Rio Negro ; but about 

 a degree and a half further south they are tolerably abun- 

 dant. When at Port Desire, in Patagonia (lat. 48), Mr. 

 Martens shot an ostrich; and I looked at it, forgetting at 



15 Liechtenstein, however, asserts (Travels, vol. ii. p. 25) that t 

 begin sitting when they have laid ten or twelve eggs; and that they 



25) that the hens 



__, _J that they continue 



laying, I presume, in another nest. This appears to me very improbable. 

 He asserts that four or five hens associate for incubation with one cock, 

 who sits only at night. 



