Chap. VIIL] INSTINCTS OF THE MOLOTHRUS. 335 



following old birds of a distinct kind and clamouring to 

 be fed by them. The parasitic habits of another species 

 of Molothrus, the M. bonariensis, are much more highly 

 developed than those of the last, but are still far from 

 perfect. This bird, as far as it is known, invariably lays 

 its eggs in the nests of strangers ; but it is remarkable 

 that several together sometimes commence to build an 

 irregular untidy nest of their own, placed in singularly 

 ill-adapted situations, as on the leaves of a large thistle. 

 They never, however, as far as Mr. Hudson has ascer- 

 tained, complete a nest for themselves. They often lay 

 so many eggs — from fifteen to twenty — in the same 

 foster-nest, that few or none can possibly be hatched. 

 They have, moreover, the extraordinary habit of pecking 

 holes in the eggs, whether of their own species or of their 

 foster-parents, which they find in the appropriated nests. 

 They drop also many eggs on the bare ground, which 

 are thus wasted. A third species, the M. pecoris of 

 North America, has acquired instincts as perfect as 

 those of the cuckoo, for it never lays more than one egg 

 in a foster-nest, so that the young bird is securely reared. 

 Mr. Hudson is a strong disbeliever in evolution, but he 

 appears to have been so much struck by the imperfect 

 instincts of the Molothrus bonariensis that he quotes 

 my words, and asks, " Must we consider these habits, 

 not as especially endowed or created instincts, but 

 as small consequences of one general law, namely, 

 transition ? " 



Various birds, as has already been remarked, occasion- 

 ally lay their eggs in the nests of other birds. This 

 habit is not very uncommon with the Gallinacese, and 

 throws some light on the singular instinct of the ostrich. 

 In this family several hen-birds unite and lay first a 

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