^°|g^^^] Thompson, Directive Coloration of Birds. 395 



DIRECTIVE COLORATION OF BIRDS. 



BY ERNEST SETON THOMPSON. 



Plate IV. 



The Protective Coloration of Birds has been much studied of 

 late, but I do not know of any paper treating of their Directive 

 Coloration. 



While living on the Plains in the eighties, I made many studies, 

 or as I then called them ' flying descriptions ' of birds, and on 

 putting these together recently in a methodic scheme I arrived 

 at a few general principles that may prove of interest. 



I can best illustrate by taking an example from mammals- 

 The common jack rabbit when squatting under a sage-bush is 

 simply a sage-gray lump without distinctive color or form. Its. 

 color in particular is wholly protective, and it is usually accident 

 rather than sharpness of vision which betrays the creature as it 

 squats. But the moment it springs, it is wholly changed. It is 

 difficult to realize that this is the same animal. It bounds away 

 with erect ears, showing the black and white markings on their 

 back and under side. The black nape is exposed, the tail is 

 carried straight down, exposing its black upper part surrounded 

 by a region of snowy white ; its legs 'and belly show clear white, 

 and everything that sees it is plainly notified that this is a jack 

 rabbit. The coyote, the fox, the wolf, the badger, etc., realize 

 that it is useless to follow ; the cottontail, the jumping rat, the 

 fawn, the prairie dog, etc., that it is needless to flee ; the young 

 jack rabbit, that this is its near relative, and the next jack rabbit 

 that this may be its mate. And thus, though incidentally useful 

 to other species at times, the sum total of all this clear labelling 

 is vastly serviceable to the jack rabbit and saves it much pains 

 to escape from real or imaginary dangers. 



As soon as it squats again all the directive marks disappear 

 and the protective gray alone is seen. 



In the bird world the same general rule applies. When sittings 

 birds zxQ protectively colored ; whenyTy///^^, directively. 



