When, after a month's labour, the Swallows have finished their dwellings, the female deposits from four to six eggs. Incubation commences, and continues from twelve to fifteen days, during which the male bird exhibits intense interest in the proceedings, carrying food continually to his mate, and passing the night in her immediate vicinity, twittering and chirping all day long to cheer the mother at her task. Two or three times in the season they thus raise a family.
From the time when the little ones are hatched the parent birds attend them with all the care their feebleness demands, and often exhibit remarkable proofs of affection. When the young Swallows feel strong enough to try their wings, the old ones tenderly guide them on their first attempts at flight, and teach them how pursuit of insects in the air is successfully performed. Boerhaave quotes an instance where a Swallow, returning from some distant excursion, found the house in which it had built its nest in flames. It did not hesitate an instant to throw itself into the fire in order to save its young.
Swallows generally prefer the proximity of a lake or river, the surface of water being always the rendezvous of crowds of insects, among which they can reap a plentiful harvest. Swallows are extremely sociable; they assemble in large flocks, and appear to be bound together by strong attachment, for they aid each other in trying circumstances.
"I have seen a Swallow," says Dupont de Nemours, "which was unfortunate, and had, I know not how, entangled its foot in a ball of string, one end of which was attached to the roof of the College of the Four Nations; its strength was exhausted, and it hung uttering painful cries at the end of the string, only endeavouring to release itself occasionally by fluttering attempts at flight. All the Swallows between the Tuileries and the Pont Neuf, and perhaps for a much greater distance, were assembled to the number of many thousands, forming a perfect cloud, uttering cries of alarm. All that came flew past, giving a peck of their bill at the fatal string; these blows, being frequently repeated, and always directed at the same spot, were finally successful, for in half an hour the string was cut and the captive set at liberty."
Another fact, related by the great naturalist Linnæus, proves how strong is the spirit of brotherhood with these birds. When the Window Swallows returned in spring to take possession of their nests, a certain number of them were found occupied by Sparrows. One of the more legitimate proprietors, thus despoiled of his property, endeavoured by every possible means to recover possession, but all was unavailing. Under these circumstances the assistance of its companions was demanded. The whole assembly proceeded to besiege the intruder. It resisted, intrenching itself in its fort, and in revenge the ousted Swallows brought mud in their bills, and actually walled up the entrance to the citadel and entombed the interloper in his cell. The truth of this account, which is repeated by many naturalists, has been denied; but Mr. McGillivray, than whom we have no more reliable author, records three well-authenticated similar instances.
The Swallow generally leaves us in the month of September in order to seek a milder climate, and one providing more abundant food in winter. Some time before their departure their cries are incessant, and great agitation is seen in their ranks; they assemble in some elevated place, as if to hold council and deliberate over their journey, and fix the date of their departure; finally, a day is decided on, which when it arrives, all the Swallows of the neighbourhood mass at an appointed place, and after certain evolutions, intended, no doubt, to determine the route, they advance in one mass towards the shores of the Mediterranean, whence they pass into Africa. Although they are of all birds the strongest on the wing, and best adapted for a long journey, they cannot accomplish this without rest if adverse winds should arise. Ships passing are frequently boarded by stragglers which light on the rigging; and both at Gibraltar and Tangiers large flocks are occasionally seen to arrive in a state of great exhaustion. Those stragglers which, through weakness or the duties of maternity, are prevented from joining the great flocks, depart some days later in smaller parties. Occasionally, however, a few individuals seem to remain with us all the year round, contriving to survive the most severe winters, which has given rise to the supposition that the Swallow has the power of hibernating, or of remaining in a state of torpor during the winter, and returning to animation in the spring. This much-controverted point has now been consigned among the mythical legends to which it belongs.
Swallows have in all ages possessed the sympathies of mankind, some of the ancients regarding them as sacred birds; nor are they ungrateful for the good feeling they excite. The services they render in destroying vast quantities of noxious insects, not to speak of their gentle habits, mutual attachment to each other, and the happy presage they bring with them of spring's advent, contribute to make them welcome visitors. Nevertheless there are instances where these proper sentiments yield to the love of destruction—where their innocent confidence is rewarded by death.
Fig. 241.—The Cliff Swallow (Hirundo fulva, Gin.).
Swallows generally have the breast and belly white, and the upper parts of the body black, tinted with a reflected blue or peach colour. There are about sixty species spread over the globe, of which six only are natives of Europe. They are divided into Swallows proper (Hirundo), Martins (Chelidons), Sand Martins (Cotyle), and Swifts (Cypselus). The Martins are larger in size than the true Swallows; have the wings longer, and consequently their powers of flight are greater and their speed more sustained; their claws are more robust and hooked.