In this family the only species which lives in confinement is the Sky-lark, and that only by very great care. It sings unceasingly in a cage, and even imitates the song of other birds. Larks are found all over the Old World, especially in Europe and Asia. The principal species are the Sky-lark (Alauda arvensis), the Crested Lark (Alauda cristata), the Wood Lark (Alauda arborea), and the Shore Lark (Alauda alpestris).
The Crested Lark (Alauda cristata), [Fig. 239], abounds on the continent of Europe, but is rare in this country, one or two specimens only being recorded. It is migratory, moving northward in spring, and again toward the south on the approach of winter. It is a handsome bird, about the size and appearance of the Sky-lark, having a few feathers on the crown forming a crest pointing backwards.
Fissirostres.
The Fissirostral Passerinæ are characterised by a broad, short bill, flattened horizontally, and slightly hooked; mandibles slightly concave; mouth very wide. They are essentially insectivorous. They comprehend three genera:—1. Swallows (Hirundo). 2. House Martins (Chelidon). 3. Sand Martins (Cotyle).
The Swallows are recognisable by their long pointed wings, forked tail, and excessively short tarsi. The air is the true element of these birds; they fly with a facility, lightness, and rapidity quite inconceivable; indeed, their existence is one eternal flight. They even feed their young on the wing when the latter first begin to fly. Watch them in the air, and they will be seen to rise and fall, tracing the shortest curves, crossing and interlacing each other's course, moderating their pace suddenly when at their utmost speed in order to follow the eccentric course of some winged insect which they have doomed for their food. Such, indeed, is the rapidity of their progress that some of the species have been known to travel at the rate of thirty leagues an hour.
Fig. 240.—Window Swallows (Hirundo rustica, Linn.).
This wonderful power, however, is only developed at the sacrifice of another locomotive faculty, for they are bad walkers. With their short limbs, activity on their feet is impossible; and if by chance they are placed on the ground, with difficulty they rise again on the wing. On the other hand, their sight is excellent—equal to even that of the Eagle or Falcon. According to Spallanzani, who made numerous experiments on the Swallows, the Martin perceives the winged fly passing through the air at the distance of more than a hundred and twenty yards.
Swallows are celebrated for their migratory journeys. In the early days of spring they reach Europe, not in flocks, but as isolated individuals or in pairs. They occupy themselves almost immediately either in repairing their last year's nests, or, if these have been destroyed, in constructing new ones. Among the arrivals are many young birds of the previous year which have not had nests, and yet it is not a little extraordinary that these, after six months' absence, return with unerring certainty to the old dwelling where hatched. This fact has been too often recorded to admit of any doubt on the subject.
The form, structure, and locality of the Swallow's nest vary with the species. The Common Swallows (H. rustica), [Fig. 240], build theirs in the upper angles of the window of some country house, under the eaves of a roof, or on the interior wall of a chimney. A chimney seems an odd place to select for such a purpose; and White of Selborne relates, not without some expressions of wonder at such a choice, that near the middle of May one of these little birds began to form her nest about five or six feet down a chimney adjoining the kitchen fire. Their nests consist of a crust or shell of mud mixed with straw, and lined with fine grass and feathers. Other species, sometimes in vast numbers, establish themselves in the clefts of dead trees. Audubon estimated at the incredible number of eleven thousand the quantity of Swallows which had taken up their dwelling in a sycamore tree (familiarly known there as a button wood) near Louisville, Kentucky, United States. Some Swallows prefer rocks or caverns, and hollow out in steep escarpments a gallery from two to three feet in depth, at the extremity of which they place their nest. Sometimes the nest is formed of twigs torn by the bird from the dead branches of trees, and bound together by a viscous liquid which flows from the bird's mouth.