As regards assertion number one, we would point out that where a flock of
herbivora is being stalked by a beast of prey, the member of the flock
nearest to the enemy—that is to say, the hindmost member—will probably be
the first to observe him. As that creature will be more unfavourably
situated for escape than the rest of the herd, it will not be to their
advantage to follow the line it has taken. Moreover, being at the rear of
the flock, it is not in a good position to take the lead, and its pursuer
is likely to see the danger signal before its friends do. It would thus
seem that “danger signals,” while possibly sometimes of service to their
possessors, are on the whole ornaments which might profitably be
dispensed with. Natural selection can scarcely be charged with the
production of a character of such doubtful utility to the organism.
Moreover, flourishing species of many gregarious animals do not possess
any “signal flag of danger,” while, on the other hand, a great many
solitary species display markings that render them very conspicuous when
in motion. Take the case of the famous Indian Paddy Bird (_Ardeola
grayii_). This, when at rest, is coloured so as to be very difficult to
distinguish from its surroundings, but flight transforms it, for it then
displays its milk-white pinions, which would make a perfect danger
signal, if only it were not peculiarly solitary in its habits. Its
gregarious brethren, the Cattle Egrets (_Bubulcus coromandus_), on the
other hand, display no danger signal.
Interbreeding of Allied Species
That these recognition marks prevent the intercrossing of allied species
and the production of infertile hybrids appears to be pure fiction. As we
have already shown, hybrids between allied species are by no means always
infertile. Moreover, species which differ only in colour seem usually to
interbreed in those parts where they meet.
“This interbreeding,” writes Finn, on page 14 of _Ornithological and
Other Oddities_, “occurs where the carrion crow (_Corvus corone_) meets
the hooded crow (_Corvus cornix_), where the European and Himalayan
goldfinches (_Carduelis carduelis_ and _C. caniceps_) encounter each
other, and where the blue rollers of India and Burma (_Coracias indicus_
and _C. affinis_) come into contact, to say nothing of other cases.”
Public-domain text, read in full here on John Shaqi.
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