The Making of Species 
unless one is near enough to see the beak, or can 
watch the bird settle and note the difference 
between the horizontal pose of the cuckoo and 
the erect bearing of the hawk, it is impossible to 
tell them apart on a casual view.” Moreover, 
the tail of the cuckoo sometimes hangs down 
vertically, thus intensifying the likeness to the 
hawk. 
It is quite possible that the brain-fever bird 
derives some benefit from the resemblance; 
indeed, it has been seen to alarm small birds, 
even as the hawk-like common cuckoo frightens 
its dupes, but, as D. Dewar pointed out, on page 
105 of vol. 57 of the Journal of the Society of 
Arts, ‘this is not sufficient to explain a likeness 
which is so faithful as to extend to the marking 
of each individual feather. When a babbler 
espies a hawk-like bird, it does not wait to inspect 
each feather before fleeing in terror; hence all 
that is necessary to the cuckoo is that it should 
bear a general resemblance to the shikra. The 
fact that the likeness extends to minute details in 
feather marking, points to the fact that in each 
case identical causes have operated to produce 
this type of plumage.” This conclusion is still 
further strengthened by the fact that the likeness 
extends to the immature plumage, that is to say, 
exists at a time when it cannot assist the cuckoo 
in its parasitical work. 
Poulton meets this objection as follows: 
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