[3]. The same birds are emigrant from some countries and not so from others: the swallows were seen at Goree in January by an ingenious philosopher of my acquaintance, and he was told that they continued there all the year; as the warmth of the climate was at all seasons sufficient for their own constitutions, and for the production of the flies that supply them with nourishment. Herodotus says, that in Libya, about the springs of the Nile, the swallows continue all the year. (L. 2.)
Quails (tetrao corturnix, Lin.) are birds of passage from the coast of Barbary to Italy, and have frequently settled in large shoals on ships fatigued with their flight. (Ray, Wisdom of God, p. 129. Derham. Physic. Theol. v. ii. p. 178,) Dr. Ruffel, in his History of Aleppo, observes that the swallows visit that country about the end of February, and having hatched their young disappear about the end of July; and returning again about the beginning of October, continue about a fortnight, and then again disappear. (P. 70.)
When my late friend Dr. Chambres, of Derby, was on the island of Caprea in the bay of Naples, he was informed that great flights of quails annually settle on that island about the beginning of May, in their passage from Africa to Europe. And that they always come when the south-east wind blows, are fatigued when they rest on this island, and are taken in such amazing quantities and sold to the Continent, that the inhabitants pay the bishop his stipend out of the profits arising from the sale of them.
The flights of these birds across the Mediterranean are recorded near three thousand years ago. "There went forth a wind from the Lord and brought quails from the sea, and let them fall upon the camp, a day's journey round about it, and they were two cubits above the earth," (Numbers, chap. ii. ver. 31.)
In our country, Mr. Pennant informs us, that some quails migrate, and others only remove from the internal parts of the island to the coasts, (Zoology, octavo, 210.) Some of the ringdoves and stares breed here, others migrate, (ibid. 510, ii.) And the slender billed small birds do not all quit these kingdoms in the winter, though the difficulty of procuring the worms and insects, that they feed on, supplies the same reason for migration to them all, (ibid. 511.)
Linnæus has observed, that in Sweden the female chaffinches quit that country in September, migrating into Holland, and leave their mates behind till their return in spring. Hence he has called them Fringilla cælebs, (Amæn. Acad. ii. 42. iv. 595.) Now in our climate both sexes of them are perennial birds. And Mr. Pennant observes that the hoopoe, chatterer, hawfinch, and crossbill, migrate into England so rarely, and at such uncertain times, as not to deserve to be ranked among our birds of passage, (ibid. 511.)
The water fowl, as geese and ducks, are better adapted for long migrations, than the other tribes of birds, as, when the weather is calm, they can not only rest themselves, or sleep upon the ocean, but possibly procure some kind of food from it.
Hence in Siberia, as soon as the lakes are frozen, the water fowl, which are very numerous, all disappear, and are supposed to fly to warmer climates, except the rail, which, from its inability for long flights, probably sleeps, like our bat, in their winter. The following account from the Journey of Professor Gmelin, may entertain the reader. "In the neighbourhood of Krasnoiark, amongst many other emigrant water fowls, we observed a great number of rails, which when pursued never took flight, but endeavoured to escape by running. We enquired how these birds, that could not fly, could retire into other countries in the winter, and were told, both by the Tartars and Assanians, that they well knew those birds could not alone pass into other countries: but when the cranes (les grues) retire in autumn, each one takes a rail (un rale) upon his back, and carries him to a warmer climate."
Recapitulation.
1. All birds of passage can exist in the climates, where they are produced.