On Mr Wallace's Theory of Birds' Nests 27,7 



instructive exercise of the peculiar habit by which the Hatching 

 Mounds are afterwards to be constructed. 



Mr Wallace next observes that the habit of ascribing of nest- 

 building to innate impulse " has had the bad effect of withdrawing 

 attention from the very evident relation that exists between the 

 structure, habits, and intelligence of birds, and the kind of nest 

 they construct." But no such effect has arisen or can possibly 

 arise from the doctrine he condemns. Those who believe that 

 the nest-building instinct is innate, believe also, of course, that 

 the structure and habits, and intelligence of birds are all equally 

 innate, and are all strictly correlated together. 



Mr Wallace next proceeds to give some explanation of the 

 peculiar nests of some birds as necessarily resulting from the physical 

 structure of those birds themselves. I do not think this explanation 

 is successful. Thus the Caprimulgidje are said to be physically in- 

 capable of weaving together moss, or fibres, or wool into a strong 

 well-constructed nest, because of their small broad bills, and their 

 feet weak in grasping power. But some of the most perfect nests in 

 the world are made by bills apparently quite as ineffective — as, for 

 example, the beautiful nest of long-tailed Tit. The bill of this bird 

 is extremely short, and not very pointed. Nor does a strong grasp 

 of foot seem necessary for the building of a nest on the ground. 

 On the other hand, many birds with a " well-formed and pointed 

 bill" make no nest at all — as, for example, the Terns and Sandpipers. 

 Nor is it true that no good materials are to be found in the haunts 

 of these birds. Dried sea-weed, and the grasses and other plants 

 which grow in abundance on the margins of lakes and seas and 

 rivers, are admirable materials for being woven, nor could any 

 implement be apparently m.ore admirably adapted for weaving 

 them than the bill of a Tern or a Sandpiper. Mr Wallace has 

 missed the real explanation in his determination to accept no 

 explanation which is not rooted in a mere physical cause. There 

 is a reason — a very manifest reason — why Terns and Sandpipers 

 should not make elaborate nests ; but there is no physical cause 

 rendering it impossible for them to do so. The reason is simply 

 this, that birds which require to breed upon the open ground, 

 must, for the purpose of concealment, make nests as small and 

 inconspicuous as possible. Even the very least collection of 

 materials upon a particular spot attracts the eye at once as it 

 ranges over any uniform or slightly varied surface ; and the 

 instructive knowledge and feeling of this fact has been given to 



