COLLECTING AND PRESERVING BIRDS' EGGS AND NESTS.
Few objects of Natural History are more interesting than the nests of
birds. To the reflecting naturalist, they open up a wide field for
inquiry. Speaking of the examination of birds, in the exercise of their
mechanical arts of constructing nests, Professor Rennie says: "This
work is the business of their lives--the duty which calls forth that
wonderful ingenuity which no experience can teach, and which no human
skill can rival. The infinite variety of modes in which the nests
of birds are constructed, and the exquisite adaptation of the nest
to the peculiar habits of the individual, offer a subject of almost
exhaustless interest." The number and variety of the eggs of birds
are curious subjects of contemplation, and should be carefully noted
whenever opportunity offers. They are as essential to the personal
history of the species as any other part of our inquiries.
The eggs are emptied of their contents by making a very small hole
at each end with a point. By blowing at one of the ends, the contents
will escape by the other, unless the young has been already formed; in
which case a larger hole must be made in the side of the egg, and the
contents removed with a small hook. The hole should then be stopped
up by pasting a little gold-beater's leaf over it. The eggs are then
either returned to their nest, in which they ought to be cemented, or
should be fixed down by one side to cards, with the name and locality
attached.
The best manner of conveying loose eggs to a distance is to put some
cotton at the bottom of the nest, and then another layer above them.
The nests should all be put up in separate boxes, if possible, and
so packed that the pressure of the lid may not injure the eggs, or a
box with several compartments should be used, taking care that each
is carefully marked. It would also be of consequence to have the
nests attached to the branches, with those species which build on
trees, which will enable us to trace the ingenious means employed by
those little animals in constructing their habitations. In sending
home specimens from a foreign country, the seams of the box should
be covered by pitched cloth, to protect them from the influence of
moisture.
To preserve the shells of eggs, first take care to clear them of their
contents; get a small, fine-pointed common syringe, such as is sold
in toy-shops, and inject the specimen with water until it comes out
quite clean. When an egg has been partly hatched or addled, the removal
of the contents generally includes that of the internal membrane or
pellicle: this makes the shell weaker. When the specimens are quite
clean internally, and have become dry (which will be in a day or two),
take the syringe and inject them with a strong solution of isinglass
(with a little sugar-candy added to prevent its cracking); blow this
out again whilst warm. Let the shell get dry, and then wash the outside
with a soft wet cloth to remove saline particles, dirt from the nest,
etc. This method varnishes the inside, and the first specimen on which
it has been tried was the before-mentioned hedge-accentor's egg, which
is to this day as bright in color as a fresh specimen.
Also in a pair of nightjar's eggs, of which species the delicate
gray tint is particularly evanescent, one was injected in the manner
described, and the other was not; in the first the gray is still
perfectly defined, in the other it has entirely disappeared. Eggs which
have lost their internal pellicle become strengthened by this process,
and those which have not lost their color greatly improved.