39^ Thompson, Directive Coloraiion of Birds. lOct 



The general rule may be topographically rendered : Color of 

 upper parts, Protective ; color of lower parts, Directive. In the 

 drawings, I have shown only certain birds of prey. All of these 

 present a distinctive pattern when viewed from below as they fly. 

 It is inconceivable that this pattern should have a protective 

 object, so if it have a purpose at all it must be a directive one. 



An evidence of this is seen in the fact that all birds with 

 ample wings and habits of displaying them bear on them dis- 

 tinctive markings — e. g., Hawks, Owls, Plovers, Gulls, etc. 

 Every field man will recall the pretty way in which most of the 

 Plovers identify themselves. As soon as they alight, they stand 

 for a moment with both wings raised straight up to display the 

 beautiful axillar pattern ; a pattern distinctively different in each 

 kind. And no doubt their end is served by telling friend or foe 

 alike that this is such and such a species. 



On the other hand birds whose wings in flight move too 

 rapidly for observation are without markings on the underside. 



Referring to the plate (Plate IV), several interesting conclu- 

 sions may be drawn. 



Though it is proverbially dangerous to classify animals with a 

 view to one set of characters only, it is nevertheless interesting 

 and often instructive. Among the Hawks the presence of the 

 wrist spot characterizes the Buteo group including the Eagles 

 and the Osprey. 



The Falcons on the other hand, in common with the Accipitrcs 

 and Circus., are without the wrist spots and have nebular banded 

 primaries. 



Exceptions to the rule that directive marks belong to the lower 

 surface are seen in the Redtail, whose rufous tail is its most 

 distinctive mark ; in the white rump-spot of the Marsh Hawk and 

 the head-markings of Goshawk, Peregrines and Sparrow Hawks. 



Among the Owls the wrist spot seems to characterize those 

 that have ' ear tufts.' 



In this brief paper and single plate I have limited myself to 

 our northern birds of prey, but enough material has been 

 gathered to justify a much more extended application of the 

 generalizations indicated. 



