that only one is really hatched. Yet Belt expressed the opinion that in
Nicaragua, where he observed humming-birds, they out-numbered all the
other birds together. Considering how abundant birds of all kinds are in
that district, and that most of them have a protective colouring and lay
several eggs, it would be impossible to accept such a statement unless
we believed that humming-birds have, practically, no enemies.

Another result of their immunity from persecution is the splendid
colouring and strange and beautiful feather ornaments distinguishing
them above all other birds; and excessive variation in this direction is
due, it seems to me, to the very causes which serve to check variation
in all other directions. In their plumage, as Martin long ago wrote,
nature has strained at every variety of effect and revelled in an
infinitude of modifications. How wonderful their garb is, with colours
so varied, so intense, yet seemingly so evanescent!--the glittering
mantle of powdered gold; the emerald green that changes to velvet black;
ruby reds and luminous scarlets; dull bronze that brightens and burns
like polished brass, and pale neutral tints that kindle to rose and
lilac-coloured flame. And to the glory of prismatic colouring are added
feather decorations, such as the racket-plumes and downy muffs of
Spathura, the crest and frills of Lophornis, the sapphire gorget burning
on the snow-white breast of Oreotrochilus, the fiery tail of Cometes,
and, amongst grotesque forms, the long pointed crest-feathers,
representing horns, and flowing-white beard adorning the piebald
goat-like face of Oxypogon.

Excessive variation in this direction is checked in nearly all other
birds by the need of a protective colouring, few kinds so greatly
excelling in strength and activity as to be able to maintain their
existence without it. Bright feathers constitute a double danger, for