1911 J Thayer, Concealing Coloration. 461 



pretations. To the superficial and unreceptive observer it rep- 

 resents merely my ingenuity. To the eye of science it is the 

 ascertaining whether the background against which the bird can 

 disappear is typically such a one as that against which he would 

 commonly be looked at by his enemy or prey. 1 Invariably, it is 

 the establishment by this means of the fact that his costume is a 

 case of concealing-coloration. For it is evident that to match 

 any one type of background, — sky, vegetation, or earth, — is all 

 that any costume could do. When all these costumes prove to 

 match the very backgrounds we think they most need to, the 

 grounds for imputing to them other reasons for their present 

 extremely complicated and exact development seem to lag super- 

 fluous. 



For instance, the vast class of black-and-gold species, so long 

 called conspicuous (birds, insects and reptiles), are essentially 

 confined to regions of vegetation, — that is, where sunlight and 

 shadow convert the whole scene itself into black and gold. Black 

 and gold is more than nine tenths of the aspect of the deepest parts 

 of such forest foliage as the sun can penetrate. This fact, appar- 

 ently so unfamiliar to naturalists, is proved by the former fact, 

 that amidst such a scene the black-and-gold species so closely 

 match as to be apt to pass unnoticed if they keep still ; — and 

 a similar correspondence holds clear through the entire animal 

 kingdom. 



Many naturalists have an absurd idea that I am telling them 

 they cannot see these species where they are conspicuous. I am 

 merely showing them that nature could do no more than she has 

 done to hide these species, condemned as they are by aerial habits 

 to many moments of contrasting background, which inevitably 

 reveal their motion. Further, that the home of the black-and- 

 gold class is where the typical background is black and gold ; — 

 and that this principle applies to all classes the world over. An 

 unthinking person must go on talking about the many creatures 

 that he sees, and never reflect on the evidence that he misses many 



1 It is even the only means of forcing the less imaginative observer to perceive 

 that he would always fail to detect any motionless live animal that happened to 

 be as favorably backgrounded, and hence to perceive that there is a percentage 

 of them that he does not discover. 



