Another species arrived soon after the chimney swallow, which I believe I have already described to you. It is called the house martin, or window swallow; but there is no end to the number of names given to this bird. It is very like the chimney swallow, but it has no spots on the tail, and its feet are differently formed, for it has the power of turning the hind toe forwards, in order to cling to a wall. This species are chilly little creatures; when there is a cold wind or rain, they press close to one another, and are sometimes so benumbed as to be caught by the hand.
It is said that after they arrive here in April, they play about for nearly a month before they begin their nests. Sometimes they build in the cliffs and rocks that hang over water; sometimes against a perpendicular wall, without having any support underneath the nest; and they show great sagacity in their mode of carrying on their work. While laying the foundations, they not only hold on by their claws, but they fix their tail against some little projecting roughness in the wall to serve as a kind of prop; and then with their bill they carefully cram mud and bits of straw into the smallest chinks in the face of the brick or stone; and to give those materials time to harden preparatory to a fresh layer, the prudent little mason only labours early in the morning, so that his work dries sufficiently in the course of the day. I have got up several times at day-break to see how neatly he uses his bill as a little trowel, while he carries the mortar or clay in one of his feet. About half an inch is laid every morning; and in ten or twelve days, a hemispherical nest is thus formed with an aperture at the top. The shell or crust is covered with rough knobs of earth; the middle is strengthened by the intermixture of straw; and the inside is nicely lined with grass and feathers; or sometimes with moss and wool. If by any accident the nest should be destroyed, it is rebuilt in a short time by the active help of many individuals who unite to assist their distressed companion. For several mornings they persisted in rebuilding a nest at the passage-room window, which had been purposely torn down each day; but, at last, after a hard struggle they gave it up.
I understand that the cliff swallows of America—who place their nests close up to the jutting ledge of a rock, or to the eave of a house—most ingeniously arch the top, and make the entrance project out and turn downwards. Frederick, who mentioned that circumstance at dinner, very philosophically remarked that, while the population of Europe was steadily extending itself from the eastern shores of America to the western side of the Mississippi, those cliff-swallows were as resolutely advancing in a contrary direction. “It appears,” said he, “from C. Buonaparte’s ‘Ornithology,’ that in ten years they had gradually established themselves in Kentucky and Ohio; in 1817 a single bird was seen skimming round a tavern, near Lake Champlain—the next year, seven were observed there—the third year, twenty-eight—and in 1822, no less than seventy had arrived in April, which is the usual time of return from their migratory travels.”
The common sparrow sometimes seizes on a swallow’s nest, before it is completed; and having driven away its owner, adapts it to his own use; but such invasions are often repelled after a spirited contest. This act of piracy has been frequently seen; but my aunt is inclined to doubt the truth of another story, though related by Linnæus, of a sparrow who took possession of a martin’s nest, and obstinately resisted the united efforts of a group of these birds which had come to the aid of the owner; but, at length, they immured the intruder by building up the entrance with the same kind of mortar of which the nest was composed.
I can see the little swallows sitting all day with their heads out of the nest near my window, gaping for their parent, who comes frequently to them with food, and clings to the edge while they gobble it up; and I understand, that after they begin to fly they are fed by their parents on the wing. I have watched for this, but could not perceive it, they are so quick in every movement. As soon as the first family are able to provide for themselves they quit their home, and while they are sporting about, and clustering and hovering round every building in the neighbourhood, the mother repairs the nest for a second brood.
27th.—The spring is now rapidly changing to summer, and the opening buds and unfolding leaves have been succeeded by a profusion of young branches, and flowers. It is, indeed, very different from the rich luxuriant spring of your Brazilian climate, but on the other hand, we have not here the perpetual rain, and the oppressive closeness of that season. The freshness of the air, the fragrance of the flowers, and the sweet song of the birds are all delightful; and every day I see some new and pretty insects. Though these insects are not quite in such numbers as, Humboldt says, appeared by turns, each at their different hours, on the Amazon river, still one may say—
Ten thousand insects in the air abound,
Flitting on glancing wings that yield a summer sound.
Just as we were looking at an uncommon butterfly to-day, Mr. Maude paid us a visit, and seeing how we were occupied, he told us that when travelling in Switzerland last June, he witnessed a very curious circumstance, in the Canton de Vaud; an emigration of butterflies. He happened to perceive something flying past the windows, and on looking out he discovered an immense flight of butterflies crossing the garden. He immediately went out, and found that they belonged to the species called, in French, La belle Dame; they were all going in the same direction, exactly from South to North, turning neither to the right nor left; people moving about the garden did not frighten them; nor were they even tempted by the numerous flowers there to alight. Their flight was low and steady, but extremely swift; and it continued in a column of several feet broad for more than two hours. As Mr. M. afterwards learned that these butterflies had been remarkably abundant near Turin, in April and May, he supposes that they had emigrated from Italy; but, he says, naturalists have been greatly puzzled to account for their having done so in a body, because they do not belong to those species that live in societies.
He mentioned another singular circumstance: when he was on Mount Etna, he saw, to his great astonishment, an immense number of insects hovering over the dry lava of one of the old craters; there was no appearance of vegetation, or of any thing that could supply them with food; but there they were in a thick mass, flitting about in the sulphurous vapour, which still rose from the crevices. The insect was a species of bug, or cimex.
Frederick took me this evening to a sunny sand-bank, to shew me a great novelty, which he had discovered there; the nest of the mason wasp. It is not common in England, and has never been found in this part of the country before. The nest is a round cavity, from two to three inches deep; which the insect bores through a hard sandy soil; and instead of throwing away the sand, as it is dug out, the little mason, by means of a glutinous fluid, forms it into oblong pellets, and arranges them round the entrance of the hole, so as to form a sort of cylindrical tunnel; which sometimes, Frederick says, is about two inches long. These little pellets are so nicely attached to each other, with regular spaces at the corners, that they have quite the appearance of filligree work. It is said that the use of the tunnel is to prevent the incursions of ichneumons, and other artful insects, who are always on the watch to intrude their own young, and who are perhaps deterred by the artificial look of this entrance. One egg only is placed in the nest; and along with it are stored, as food for the future young, several fat grubs. But these are always full grown, because, as they are just about to pass into the pupa state, they require no food for themselves.