Vol. XVII 
1900 
THAYER, Banner Mark Theory. let 
with protective gradation to carry the aspect of the vertical stems, 
etc., right across the animal, so as to help him disappear. 
To sum up: The pattern on the wings of Hawks and Owls, 
the world over, varies to a surprisingly small degree, which could 
not be the case if its main object were the distinguishing of the 
species from each other. Surely no one imagines that it has 
developed to help show to the rest of the animal kingdom that 
its wearer is not a Duck, and it shows no propensity to try to 
distinguish such nearly allied forms as could need it. For 
instance, even human beings know at a glance the long sharp 
wing of a Falcon from the broad round one of an Accipiter, long 
before they are near enough to see the pattern, yet the different 
species within each of these genera have almost identical under 
wing patterns. ‘The tail of the American Sparrow Hawk, especi- 
ally that of the male, is certainly an exception. 
Unquestionally Grouse, etc., know an Accipiter from a Buteo 
without looking for what Mr. Thompson called, by a slip of the 
mind, the “ wrist-mark,”’ and still more obviously must this be the 
case between the Hawks themselves, for whose benefit alone 
this pattern could exist, if recognition were its object. In short, 
if these markings were mainly for identification of one Cooper’s 
Hawk to another, they would avoid the Sharpshin’s pattern, while 
if they were meant to announce the wearer to a Grouse they 
would hurt his hunting-chances, and we should see, in the Accipi- 
ter’s wing, signs of imitating the pattern of some harmless Hawk. 
In other words the advocate of the “banner mark” theory in 
the case of the under pattern of Hawks’ and Owls’ wings must 
face the fact that these birds live mainly in woods or smaller 
vegetation, and wear, even on the underside of their wings, the 
very patterns nature furnishes to a vast number of vegetation- 
dwellers, both of birds and mammals; while these patterns are 
nowhere, or as good as nowhere, found on any species that live 
wholly away from vegetation. Then, if he still believes that what 
difference there is, is for recognition, well and good; only, were 
recognition the mazz use, why do even their under wings retain 
the twig pattern which tends to efface the wing by its resemblance 
to the twigs and parallel distant tree-trunks, which in the woods 
form its background, and thus make it harder to distinguish, 
