Auk 
108 THAYER, Banner Mark Theory Agi 
ARGUMENTS AGAINST THE BANNER MARK 
THEORY: 
BY ABBOTT H. THAYER. 
THE following paper is an attempt to show that the Directive 
Coloration theory is largely a mistake, and that so-called ‘ banner 
marks’ belong to the greater class of protection patterns and pro- 
tective colorations. And, secondly, that in many cases they do 
not serve even in a minor degree as ‘ banner marks.’ 
Of course, to any one who feels the inevitability of Natural 
Selection, it is obvious that each organ or structural detail, and 
likewise each quality of organic forms, owes tts existence to the sum 
of all its uses, so that while it is sustained at a certain stage of 
development mainly by the value of its principal function, this is 
only to the degree to which it can perform this without hostility 
to the other requirements of the organism, each one of the latter 
modifying it in proportion to its own importance. So that when 
one says an animal’s markings are for this purpose or for that, he 
speaks inaccurately. Whenever we can know the relative impor- 
tance of mutual recognition as compared to concealment, and then 
how much markings help recognition, and how much they help 
concealment, we shall be in the right track, though still ignoring 
many factors. 
The so-called ‘ banner marks,’ or, as Mr. Thompson has termed 
them, “ directive coloration marks’ of birds and mammals,! have 
never seemed to me satisfactorily explained by the theory that 
they exist mainly to aid other animals, both of the same species 
and of others, both friendly and hostile, to recognize the bearer 
of the ‘banner marks.’ Such means seem to me far too crude to 
play a prominent part in aiding the recognition powers of a class 
of beings who do so obviously inter-communicate, in many cases 
by means infinitely more subtile and much more akin to such 
instinctive methods as guide even the Indian and to some extent 
the white hunter in the chase. These men could not possibly 
1 Auk, Vol. XIV. pp. 395, 396, pl. iv. 
