THE CRUDEST NEST FORMS 85 



tioned, being merely hollows in the ground, into 

 which a little dry grass or other vegetable fragments 

 are collected. These nests, however, finally receive a 

 warm and copious lining of down. 



In bringing this review of crude nest-forms to a 

 conclusion, it may be well to point out the following 

 facts which their scientific study seems to suggest. 

 In the first place the number of species that may 

 fairly be classed as builders of the crudest forms of 

 nest is very little short of two thousand five hundred, 

 or considerably more than one-fifth of the known 

 species of birds. The significance of this fact cannot 

 be over-estimated in demonstrating how certain con- 

 ditions of life determine this crude type of architec- 

 ture and inexorably preserve it. Two other facts 

 are brought into very suggestive prominence by this 

 cursory review of the crudest forms of nest. The 

 first is that an exceptionally large percentage of the 

 species are either aquatic or terrestrial in their habits, 

 and naturally select the ground as a site for their 

 procreant cradle. In such a situation an elaborate 

 or bulky nest would in a vast number of instances be 

 exceedingly conspicuous, so that we see a slight and 

 crude nest is the one best adapted to the conditions 

 of existence. The second fact is that the young of an 

 equally large percentage of these crude nest-builders 

 are hatched in a condition that renders them inde- 

 pendent of a nest, being in many cases able to run 

 almost as soon as they break from the shell, or are at 



