360 OUR RARER BIRDS 



One of the great points brought forward in favour of In- 

 stinct is the uniformity of the nests of the birds of each 

 species, even though they be widely spread, in localities where 

 they are subjected to various conditions. If this was strictly 

 true, I think it would go far to prove the existence of In- 

 stinct ; but it is not ; for birds, even within the memory of 

 living man, have been known to change and improve their 

 nests under the influence of altered conditions. If a bird 

 built by Instinct, it is fair to assume that that Instinct is 

 unchangeable, and only allows the bird to build on a certain 

 plan. Instinct practically remains stationary ; Reason, how- 

 ever, advances. What proof have we of this ? Swallows are 

 a most interesting instance they having partially ceased to 

 build on rocks or in caves, choosing houses and sheds instead. 

 Starlings and many other birds will readily take advantage 

 of a box placed on the house-side for them, and abandon their 

 holes in the trees for the new quarters ; Titmice will do the 

 same. The House Sparrow is another instance of a recently 

 changed mode of nest-building ; so is the Moorhen, which 

 often builds in trees in districts liable to sudden floods. Many 

 other instances might be given, all tending to prove that birds 

 are capable of taking advantage of any favourable circum- 

 stances to alter and improve their nests a fact which can 

 only be accounted for by the direct influence of their reasoning 

 faculties. 



I think we should be very careful in imputing the various 

 apparent imperfections (and the perfections, too) in the archi- 

 tectural qualities of birds' nests to the appliances or tools 

 with which they are constructed. To far more important 

 causes I believe the many differences in these structures may 

 be safely attributed ; and instead, therefore, of viewing the 

 Swift's rude nest, or the Ring Dove's wicker cradle, as the 

 inevitable results of imperfect natural appliances, they should 

 be viewed as structures made perfect for the purpose they 



