^°'i9if ^"^J McAtee, Recognition Marks. 229 



It is evident that in such cases (frequent among Shore-birds) that 

 some condition is more important than the possession of the regu- 

 lation directive marks of the species. 



If recognition marks are so important to flocking species, why 

 is it that their usefulness is swamped, as it were, in many cases, 

 by the flocking together of distinct species? 



For instance during the only time that Shore-birds, Ducks, Geese, 

 Swallows, Sparrows and Warblers flock, distinct species show no 

 aversion to flocking together; in fact they habitually do this very 

 thing. 



Why do directively colored species ignore the hall mark of their 

 kind, and crossmate? 



This is done promiscuously and freely by Anatinse; other 

 examples are Vermivora and probably Colaptes. 



We may well inquire also why certain very closely related species 

 do not have recognition marks? For instance, Sturnella magna 

 and Sturnella neglecta; and certain species of Empidonaz and 

 Vireo. 



Species in which all of the individuals are not colored alike, or 

 do not have certain conspicuous markings in common, cannot be 

 said to have specific recognition marks. This category includes 

 those species the young of which are very different in color from 

 the adults, a condition that persists for two or three years or more 

 in certain cases. With them must be grouped also, the dichro- 

 matic Screech Owl, the four species of Buteonidce, and the three 

 Jaegers that have a normal melanistic phase, and the numerous 

 species which exhibit completely or nearly completely distinct 

 sexual coloration, either at certain seasons or permanently. We 

 may well enquire therefore how such species as these have made a 

 success of the struggle for existence without the aid of the highly 

 esteemed recognition marks? 



If recognition marks are of vital importance why are they so 

 variable? 



They vary extremely in the Mniotiltidae, as the writer knows 

 from a special study of the subject. White blotches may be 

 present on anywhere from two to five pairs of rectrices in the same 

 species. The white wing spot so characteristic of Dendroica 

 ccerulescens varies greatly, and is sometimes absent. Both the 

 primary blotch and tail spots may be lacking in the same specimen. 



