58



Dr. A. G. Butleb,



Whereas I have always maintained that a great deal too much

stress lias been laid upon the importance of evidence afforded by the

acceptance or rejection of certain forms of living food by animals in

captivity and have always expressed my entire disbelief in the theory

of warning colours, that disbelief being itself based upon the study of

my own birds during the past thirty years, I think Mr. McAtee goes

too far in assuming that the numerous experiments made by many

observers with reference to protection are utterly valueless.


It is doubtless true that wild birds, which are able to hunt for

food over large tracts of country, naturally prey upon those creatures

for which they have a decided preference whenever the latter are

obtainable ; but in seasons of drought, when their favourite food is

scarce, they undoubtedly pursue and devour what they can get

provided that it is not utterly distasteful ; thus last year, when we

had an unusually long dry hot summer, I repeatedly saw the common

House-Sparrow chasing and devouring all three species of our

common white butterflies :—Ganoris brassicce, rapce, and napi, the

wings of which they snipped off before eating the bodies. That

many birds do eat butterflies in their wild state is proved by the

numbers sent home from abroad with triangular gaps cleanly

snipped out of their wings evidently by the beak of a pursuing

bird.


To assume that captive birds accept certain food which they

would never look at in an unconfined state is to beg the question : a

hungry bird would probably accept it eagerly, just as a hungry bird

would certainly examine a leaf-like butterfly or a stick-like cater¬

pillar if it came across it while searching for insect food upon a tree

or shrub ; in cases of that kind the legs and perhaps the antennae of

the butterfly would be noticed and the short true legs or prolegs of

the caterpillar would probably attract attention : this would induce

the bird to test the character of the mimetic form with its beak and,

if palatable, it would undoubtedly be devoured : a study of living

birds in flight-cage and aviary enables us to be sure of this.


I have never known any captive bird to exhibit fear of what

are called warning colours in insects ; they sometimes ignore certain

startlingly coloured insects altogether and at other times they peck at

and either accept or reject them. It is true that anything very



