6o 



ANIMAL INSTINCT AND INTELLIGENCE 



of the eggs or young, are often associated with that for nest- 

 building. Of this the Eider- Duck (Somateria mollissima, fig. 

 1063) may be taken as an example. Egg-laying and building 



are here not consecutive acts, but 

 the former takes place at intervals 

 during the latter, in a somewhat 

 variable fashion. Three succes- 

 sive stages ,re shown in the illus- 

 tration, which is taken from photo- 

 graphs by Mr. R. A. L. Van 

 Someren. The first represents 

 four eggs resting in the incom- 

 plete nest, and the second (on a 

 larger scale) the complete down- 

 lined nest with its full complement 

 of eggs. The third figure shows 

 the same nest during the tem- 

 porary absence of the mother-bird, 

 and illustrates an interesting as- 

 sociated instinct. Before leaving 

 her duties she had pulled the 

 down over the eggs, so as to 

 cover them completely, an act dis- 

 tinctly conducive to their welfare. 

 For, snugly tucked up under their 

 " eider-down quilt", they were not 

 only kept warm, but also, as the 

 figure clearly proves, effectively 

 screened from observation. 



But although nest-building is 

 almost certainly instinctive in the 

 main, it is subject to modification 

 in individual cases in ways which 

 vouch for the intelligence of the 

 builders. And such modification 

 ma y affect the style, materials, 

 and place of construction. Often- 

 quoted illustrations are those of the House-Swallow and House- 

 Martin, which have taken advantage of the evolution of human 

 civilization so far as concerned with domestic architecture. 



Fig. io6 3 .-NestoftheEider-Duck(^ w ^^ 



tnollissima). See Text. 



