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Particularly in the study of insects it has been shown that bright
or contrasting and conspicuous colors tend to be associated with
ill-flavor in the animals that wear them, while insects with a good
flavor tend to be so colored that they are difficult to see. The
first is a warning coloration--advertising to a predator that he will
not enjoy eating this insect and better leave it alone; the other
is concealing color, its function apparently to keep predators from
finding their prey. The tasters in the experiments that have been
used to work out the above generalizations were usually birds, but,
as checks, a variety of other animals were used, and the magpie moth
(_Abraxas grossulariata_), for instance, was found to be distasteful
to certain spiders, frogs, lizards, various birds, a bat, and finally
"the late Dr. Hans Gadow (one of the leading ornithologists of his
day), who made a practice of sampling caterpillars, remarked on trying
an _A. grossulariata_ that it was quite one of the worst he had ever
eaten!" Apparently ideas in taste are similar throughout large sections
of the predatory animal world. Reversing the usual role, and using
insects (hornets) as tasters of bird flesh, the celebrated British
naturalist, Dr. H. B. Cott, has recently studied the question of
the palatability in birds and their coloration. Naturally Dr. Cott,
with his customary thoroughness, compared hornets as tasters with
other animals, including cats and men, and found a surprisingly close
agreement in the results.
The experimental procedure was to expose the flesh of two different
birds (without feathers) at the same time, and see which the wasps ate
first. Thus a graded series was built up of the 38 species of birds
tested, with a palatability rating of from 1 to 38. The wryneck and the
crested lark stood at the top of the list, and the pied kingfisher and
the white-rumped black chat, as the least palatable, at the bottom with
Numbers 37 and 38.
Then, surveying the coloration of the birds, and their habits, Dr. Cott
made the important correlation that in general the birds whose flesh
was most edible were protectively colored, and those whose flesh was
least palatable tended to be conspicuous in color and behavior!
To relate it to the theory of evolution Cott concludes that selective
pressure by predators seems to have forced vulnerable species along
two divergent lines of specialization: leading in those which are
relatively palatable toward concealment, and in those which are
relatively distasteful toward advertisement.