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From The Passenger Pigeon in Pennsylvania
By John C. French
CHAPTER XIII
Other American Varieties Also Noticed
Development from Egg Observed and Given a Careful Analysis
In addition to a great variety of doves and the two varieties of northern pigeons, Ectopistes and Fasciata, there are various other important pigeons, native in North America and the West India Islands, that may be briefly noticed, in glancing around the Carribean environment and other places that are familiar to us. The White-Headed Pigeon (Columbia cucocephala) is found at Key West, Florida, in secluded places, as it is a shy bird, arriving about April 20th. It is of two classes that are plenty in Honduras and Jamaica and called Mangrove Baldpate and Mountain Baldpate, respectively, according to the chief habitat of each class. There is demand for the delicious squabs. They are readily domesticated, but have a fondness for emancipation. They are seldom taken in mainland interiors, but they love the islands near the coasts. It is smaller than the passenger pigeon; but is plump and nearly as heavy; color, dark slate blue; from bill to nape pure white; dark maroon-purple spot on the occiput, and below it a brassy-green cape, covering nape, each feather bordered externally with velvety black; the bill is dark purple, with a light blue tip; iris, white; and the legs, a deep lake-red.
The Blue-Headed Pigeon (Starnoenas cyanocephala) is another West Indian bird that visits Key West. It is somewhat like a quail in appearance and in some of its habits, with a blue bill and carmine feet. It is about twelve inches in length. There are doves of approximately the same size, and some are larger. The Red-bill, the White wing in Mexico, Zenaida at the Florida Keys and in the Antilles, the Zenaidura in the Carolinas, Louisiana and California. It visits New England in summer and may be seen in all the states, occasionally, from the Atlantic to the Pacific, in its migratory flights, having a variety of local names and somewhat varying plumage; it is Ortolan in Louisiana; Mourning Dove or Common Dove, in other states, where its rapid flight and whistling wings are known to the country school children at the roadsides, and in the silent barren. In the Atlantic and Gulf states, as far as Carolina, the tiny Ground Dove is know to everyone; and the Scaly Dove (Scardafella Inca) may be seen along the Rio Grande; in Arizona and southwards to Guatemala, in two species, one of which may also be seen in South America.
There are many more individual illustrations of the varying orders to which the many pigeon tribes belong, but those already described are sufficient for our purpose, at the present time. Domesticated pigeons are found to be sufficiently parallel with the native wild species of America to pursue our general investigations upon; so we take a pigeon egg, weighing about half an ounce, with rounded ends similar, instead of one end pointed, as in the case of domestic fowls; and the shell is white. Birds are classed as vertebrates, but do not suckle their young, nourishing them, as explained in earlier chapters, as regards pigeons, with partially macerated food from the pouch of either parent bird, acted upon by its own organs of digestion; and which they are able to disgorge at will, similar to ruminating quadrupeds. The young are produced in an animated state, from the eggs, by the effects of constant warmth, as the parent pigeons sit alternately upon the nest.
When the egg is first produced, the future squab is indicated by a little germ-spot, barely the size of a single oat grain with hull and shuck removed; without power of breathing atmospheric air and receiving nourishment into its mouth, until the incubating period has elapsed. To watch the development in the egg is an interesting experiment and full of suggestive instruction. The structure is so balanced, that to view the little germ-spot it is only necessary to lay the egg on its side and remove a portion of the shell, when the germ will be seen lying immediately under the aperture. In whatever way the egg may be turned, the germ-spot presents itself, at the highest point, and that the living principle has not been extinguished. As growth proceeds, manipulation becomes easier, but it is best to immerse the egg in water, before removing the shell, and to keep it submerged during examination.
It is wonderful to see a living being evolved from apparently lifeless substances contained in an egg. The being grows under our gaze, and we arise from the wondrous spectacle with a feeling that we have been present at an act of creation. When an egg is opened we find a mass that is usually denominated as “white” and “yolk”; but examined more closely, the contents are found elaborately disposed, so as to meet the object for which the egg is formed. Within the shell lies a membrane, composed of two layers, pressed closely together for the greater portion of its extent, but separated at the wider end of the egg, containing a supply of air to satisfy the squab’s requirements. This space increases as the squab develops. Within the white lies the yolk, surrounded by a slight membrane guarding it from the white. The yolk is anchored by two ligaments fastened to its membrane. Upon the yolk, and immediately under the membrane, lies the little germ which in the brief space of two weeks of incubation will develop into a squab bird.
After a few hours of warmth, the first idea of life is seen in a little whitish streak, barely a tenth of an inch long, wider at one end, lying across the egg. This streak enlarges and forms a groove between two little ridges, in which a delicate thread appears, a few hours later, the first indication of a spinal cord. Presently a number of the tiniest square, white plates are seen on each side of the thread, the commencement of the vertebrae. The parts seem to be a crystallization from the substances of the egg. By the end of the first day the germ curves, looking like a tiny maggot as it lies on the edge of the yolk. The little heart is perceptible, the second day; the arteries and veins supplied with blood, are perceived the third day. So the various organs appear, one after another, as the body is built up; the feathers being the last, on the twelfth day, and the squab pierces the air-sack, with its beak, at the blunter end of the egg; and hammers on the shell with its horn tipped beak.
The young bird has been nourished by the yolk, which is connected
with its abdomen, and which is separated soon after the shell is broken,
enabling the squab to respire freely. The shell is pecked in a circle,
cutting for itself a trap-door, which often remains suspended by a hinge
of uncut lining membrane, through which the squab emerges on the fourteenth
or fifteenth day after the incubation began, and the horny excrescence
at the tip of its bill soon drops off, as the young bird no longer needs
a chisel to cut through so hard a substance as an egg shell; and nature
abhors a superfluity in all her craftsmanship. The young bird remains
in the nest, nourished by the parents, for about two weeks, growing a coat
of feathers upon its naked body, and quills for wings and tail, the sails
and rudder by which it then parachutes from the high branch of the home
nest-tree, in a slanting route, as it flutters to the ground and begins
its life work of finding its own food and learning how to fly, which requires
only a few days of practice, when the squab hastens to rejoin its kindred,
in the distant home they have selected and migrated to, soon after their
young fluttered from the nests to begin active life in a wide world, where
their natural enemies sought their destruction, making them hustle.
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