|
|
|
Continued from Subjective Structural, Prismatic or Metallic Colors
The effects of natural selection and choice of
breeding partners, whether combining or striving against each other, have
worked marvels in plumage. Significant colours, as for instance total blackness
or whiteness, could be developed only when higher intellectual qualities,
bodily size and strength, or occasionally even special smallness, guaranteed
the safety of the bird. The females and the young mostly retain a more
sombre garb, and thus remain on a phylogenetically lower level. It takes
the large Gulls several years to change from a mottled brownish and grey
appearance into the beautifully dark and white colours. The same applies
to the white shoulders of certain Eagles.
Many other instances show clearly how the changes of bygone ages of the
ancestors are recapitulated in the yearly moult of the growing individual
until with maturity its present stage of perfection is reached - but only
its present stage, because its descendants in turn will be different, either
still more beautiful or still better adapted to the ever-changing conditions
of life.
|
|
|
This consideration implies that whole-coloured
birds, like Swans and Ravens, have reached their limit so far as coloration
is concerned, since both black and white are very conspicuous and are correlated
with a considerable amount of intellectual development. The very early
assumption of the black plumage by the nestlings of Ravens and Crows is
a strong argument for their relatively highest position on the hypothetical
avine tree.
Albinos are notoriously shy. The females of birds
which breed in holes, as Rollers, Kingfishers, and Parrots, are frequently
as beautifully coloured as the males, because they need no protection through
colour while sitting on the nest. In the green Amazons beauty, intelligence,
and safety by protection are combined.
|
|
The often surprising adaptation of the coloration
of the plumage to the surroundings is well known. Frequently the conspicuoulsy
coloured parts are hidden when the bird is at rest, and are only exposed
or shown-occasionally as "danger signals" when the bird is on the wing.
It cannot be doubted that the sense of colour is highly developed in birds,
perhaps most so in the female when choosing a mate. The result of
this mating selection being constantly regulated by natural selection is
exhibited most by the male, but enjoyed by both sexes, and for the benefit
of the whole race.
|
|
|
