THE WILLOW AND WOOD WARBLERS 41 

 even these can be identified by the practised 

 eye. 



Two Httle migrants, the Willow Warbler 

 (Phylloscopus trochilus) and the Wood Warbler 

 (P- sibilatrix), build similar oven-shaped nests 

 on or close to the ground. Though outwardly 

 resembling one another, there is no difficulty 

 in distinguishing them. It is a curious fact, 

 that whilst the willow warbler elects to hne 

 her nest with massed feathers, the wood 

 warbler never uses a single feather as lining. 



No matter in what country these birds are 

 known to build, this is invariably the case. It 

 is impossible to conjecture a reason for this 

 divergence. Why, we may ask, should feathers 

 not be used in both cases, or in neither case, 

 when the habits and mode of life of these two 

 species is practically the same ? We may feel 

 sure, however, that this arrangement is not 

 without design ; when understood, nature's 

 adaptations are always purposeful. Again we 

 marvel, how can the one bird know that in her 

 case feathers must be collected and placed for 

 a lining, and in the other that feathers must 

 not be taken inside the nest ? Such knowledge 

 in these tiny creatures is not of themselves, 

 acquired, but spontaneous — of the Absolute. 



The nests of these warblers are so wonder- 

 fully concealed in the undergrowth of woods 



