It Frequents The Forests Of The Interior,
And Comes Down To The Sea-Beach To Deposit Its Eggs, But Instead
Of making a mound, or scratching a hole to receive them, it
burrows into the sand to the depth of
About three feet obliquely
downwards, and deposits its eggs at the bottom. It then loosely
covers up the mouth of the hole, and is said by the natives to
obliterate and disguise its own footmarks leading to and from the
hole, by making many other tracks and scratches in the
neighbourhood. It lays its eggs only at night, and at Bouru a
bird was caught early one morning as it was coming out of its
hole, in which several eggs were found. All these birds seem to
be semi-nocturnal, for their loud wailing cries may be constantly
heard late into the night and long before daybreak in the
morning. The eggs are all of a rusty red colour, and very large
for the size of the bird, being generally three or three and a
quarter inches long, by two or two and a quarter wide. They are
very good eating, and are much sought after by the natives.
Another large and extraordinary bird is the Cassowary, which
inhabits the island of Ceram only. It is a stout and strong bird,
standing five or six feet high, and covered with long coarse
black hair-like feathers. The head is ornamented with a large
horny calque or helmet, and the bare skin of the neck is
conspicuous with bright blue and red colours. The wings are quite
absent, and are replaced by a group of horny black spines like
blunt porcupine quills.
These birds wander about the vast mountainous forests that cover
the island of Ceram, feeding chiefly on fallen fruits, and on
insects or crustacea. The female lays from three to five large
and beautifully shagreened green eggs upon a bed of leaves, the
male and female sitting upon them alternately for about a month.
This bird is the helmeted cassowary (Casuarius galeatus) of
naturalists, and was for a long time the only species known.
Others have since been discovered in New Guinea, New Britain, and
North Australia.
It was in the Moluccas that I first discovered undoubted cases of
"mimicry" among birds, and these are so curious that I must
briefly describe them. It will be as well, however, first to
explain what is meant by mimicry in natural history. At page 205
of the first volume of this work, I have described a butterfly
which, when at rest, so closely resembles a dead leaf, that it
thereby escape the attacks of its enemies. This is termed a
"protective resemblance." If however the butterfly, being itself
savoury morsel to birds, had closely resembled another butterfly
which was disagreeable to birds, and therefore never eaten by
them, it would be as well protected as if it resembled a leaf;
and this is what has been happily termed "mimicry" by Mr. Bates,
who first discovered the object of these curious external
imitations of one insect by another belonging to a distinct genus
or family, and sometimes even to a distinct order. The clear-
winged moth which resemble wasps and hornets are the best
examples of "mimicry" in our own country.
For a long time all the known cases of exact resemblance of one
creature to quite a different one were confined to insects, and
it was therefore with great pleasure that I discovered in the
island of Bouru two birds which I constantly mistook for each
other, and which yet belonged to two distinct and somewhat
distant families. One of these is a honeysucker named
Tropidorhynchus bouruensis, and the other a kind of oriole, which
has been called Mimeta bouruensis. The oriole resembles the
honeysucker in the following particulars: the upper and under
surfaces of the two birds are exactly of the same tints of dark
and light brown; the Tropidorhynchus has a large bare black patch
round the eyes; this is copied in the Mimeta by a patch of black
feathers. The top of the head of the Tropidorhynchus has a scaly
appearance from the narrow scale-formed feathers, which are
imitated by the broader feathers of the Mimeta having a dusky
line down each. The Tropidorhynchus has a pale ruff formed of
curious recurved feathers on the nape (which has given the whole
genus the name of Friar birds); this is represented in the Mimeta
by a pale band in the same position. Lastly, the bill of the
Tropidorhynchus is raised into a protuberant keel at the base,
and the Mimeta has the same character, although it is not a
common one in the genus. The result is, that on a superficial
examination the birds are identical, although they leave
important structural differences, and cannot be placed near each
other in any natural arrangement.
In the adjacent island of Ceram we find very distinct species of
both these genera, and, strange to say, these resemble each other
quite as closely as do those of Bouru The Tropidorhynchus
subcornutus is of an earthy brown colour, washed with ochreish
yellow, with bare orbits, dusky: cheeks, and the usual recurved
nape-ruff: The Mimeta forsteni which accompanies it, is
absolutely identical in the tints of every part of the body, and
the details are copied just as minutely as in the former species.
We have two kinds of evidence to tell us which bird in this case
is the model, and which the copy. The honeysuckers are coloured
in a manner which is very general in the whole family to which
they belong, while the orioles seem to have departed from the gay
yellow tints so common among their allies. We should therefore
conclude that it is the latter who mimic the former. If so,
however, they must derive some advantage from the imitation, and
as they are certainly weak birds, with small feet and claws, they
may require it. Now the Tropidorhynchi are very strong and active
birds, having powerful grasping claws, and long, curved, sharp
beaks.
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