A large number of species have a bright or nearly bright
guiar spot. This is most remarkable in Synallaxis phryganophila, the
chin being sulphur-yellow, beneath which is a spot of velvet-black, and
on either side a white patch, the throat thus having three strongly
contrasted colours, arranged in four divisions. The presence of this
bright throat spot in so many species cannot very well be attributed to
voluntary sexual selection, although believers in that theory are of
course at liberty to imagine that when engaged in courtship, the male
bird, or rather male and female both, as both sexes possess the spot,
hold up their heads vertically to exhibit it. Perhaps it would be safer
to look on it as a mere casual variation, which, like the exquisitely
pencilled feathers and delicate tints on the concealed sides and under
surfaces of the wings of many species possessing outwardly an obscure
protective colouring, is neither injurious nor beneficial in any way,
either to the birds or to the theory. It is more than probable, however,
that in such small feeble-winged, persecuted birds, this spot of colour
would prove highly dangerous on any conspicuous part of the body. In
some of the more vigorous, active species, we can see a tendency towards
a brighter colouring on large, exposed surfaces. In Auto-malus the tail
is bright satiny rufous; in Pseudo-colaptes the entire under surface is
rufous of a peculiar vivid tint, verging on orange or red; in Magarornis
the bosom is black, and beautifully ornamented with small leaf-shaped
spots of a delicate straw-colour.
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