178 FRANCIS H. HERRICK 



feet or poorly construeted nests have been often attributed to 

 the youth or inexperience of the builder, but in most cases, as 

 it seems, upon insufficient grounds. The theory of instinct 

 requires adequateness only in the first nest of any builder, never 

 absolute conformity; we should expect the first nest of a robin 

 to be as adequate for the purposes to which it is put, as the 

 first nest of a mud dauber, or the first egg-cocoon of a spider, 

 but we should not expect so great conformity to specific type 

 in the more plastic bird, where practice must tend to make 

 " perfect," and where the impulses which are due to heredity 

 are modified in a far higher degree by experience. While obser- 

 vations under this head are almost nil, suspicions abound, and 

 we would suggest that the question of imperative need for a 

 nest, due to disturbance of any sort, whether from enemies, 

 the weather, or a lack of the mutual attunement of the serial 

 instincts themselves, cannot be left out of the account, although 

 it must be admitted that they are often difficult to determine. 



Aside from conformity to specific type, the best single criterion 

 of perfection in nest-building is fitness or adaptability in the 

 species or the individual. Yet many cases could be cited in 

 which nests conform admirably to specific type, but are rather 

 poorly adapted to protect either eggs or young, even in the 

 situations usually chosen. Thus the neatly molded grass and 

 hair nests of chipping sparrows are commonly too thin and 

 flimsy, and too insecurely anchored to their supports to stand 

 the tests of wind and weather to which they are apt to be sub- 

 jected; the abundance of such birds seems to be due more to 

 fertility and persistence than to skill in building. There are 

 other birds, again, like some of the terns, which have never 

 learned that a bare, wind-swept rock is a poor cradle for even 

 a pyriform egg, though they have doubtless tried the experi- 

 ment for ages, or that a rock-pocket is liable to fill with rain 

 water and drown their progeny, whether egg or young. 



There are birds in which a definite type of nest does not seem 

 to have been established, yet it must be admitted that the sig- 

 nificance of variation in such cases has seldom been determined. 

 Thus, certain Indian wren-warblers (Prinia) sometimes suspend 

 their nests by stitching together a few leaves, like the tailor- 

 bird, or dispensing with such support, model a simple cup like 

 so many other species. Such birds seem to be the despair of 



