Part 24

The causes that govern the migratory movements of birds are still unknown. Some species are doubtless impelled by stress of weather or lack of food to seek other quarters, but what power can it be that brings the Swift thousands of miles from another continent to lay its eggs and rear its young, and then precipitately to retire again when the flies on which they feed are most abundant, and the warmest month of the year has hardly begun? It is one of the last of the summer birds to arrive, May being generally well advanced before we hear its harsh yet pleasant scream of "swee ree," as it swerves in rapid flight round the cottage or belfry which is to form its summer home.

This species is the most aerial of all our native birds, and is never seen to settle except when entering the hole under the eaves where it nests, and, in fact, owing to the length of its wing and shortness of its legs, it cannot raise itself from a level surface should it once settle.

Gregarious in its habits, it returns yearly to the same place, and, entering through a hole or crevice under the eaves, nests there in security. Swifts, as a family, differ from all other birds in using a sticky, mucous saliva, with which to bind together rough bits of straw, cobwebs, feathers, etc., which form their nest. The nests of certain foreign species are formed entirely of this saliva, and such nests are eaten with great relish and in large quantities by the Chinese. With our species, however, the amount of saliva used is comparatively small; it does not often collect material for its nest, but makes use of the accumulation of rubbish usually found under roofs, and, hollowing out a shallow depression, cements it into a permanent cup. Two or three dull, oblong, white eggs form the clutch. The young when first hatched are naked; they stay in the nest a long time, not leaving it until fully fledged. When, however, they leave their home and drop into the air for the first time, they fly off at once and appear as much at home on the wing as their parents. For a few days they return to the nest to rest, and then a week or two after they are fledged, about the beginning of August, they leave us for their tropical winter home. These birds occasionally perform curious aerial evolutions on warm summer nights. As darkness comes on they become very restless, screaming round the tower or belfry as they dash by in wide circles; gradually they rise higher and higher in the air till they become mere specks, and are finally lost in the darkness.

Here again our ignorance comes in and our story must end. Observers have sat up in vain till two or three in the morning, awaiting their return. Not one has reappeared, and yet the next day they will all be seen back again, apparently unwearied by their restless night, but rather enjoying to the full the marvellous powers of flight which they have inherited.

The sexes and young are alike in plumage and are of a uniformly dark sooty brown, the chin and throat being dull white. The tail is short and slightly forked; wings very long and narrow. The feet are extremely feeble, the four toes all directed forward and having sharp, recurved nails, which enable them to cling to perpendicular surfaces. Length 6·5 in.; wing 6·8 in. It is generally abundantly distributed throughout our islands, but becomes scarcer in the North. It winters in Africa.

THE ALPINE SWIFT Cypselus melba, Linnæus

This is a much larger species than our common Swift and has only visited these islands on very rare occasions, almost all the examples obtained having been taken in the south of England. It breeds in the high mountain ranges of Central and Southern Europe, and winters in Africa. From our common species it may be distinguished by its larger size, browner colour, and light under parts. Length 8 in.; wing 8·45 in.

Another species, the Needle-tailed Swift (Acanthyllis caudacuta) has occurred on two occasions in England. It breeds in Central Asia, migrating in winter to Australia, and except for these two instances is unrecorded from Europe.

THE NIGHTJAR Caprimulgus europæus (Linnæus)

Arriving, the latest of all our migrants, towards the middle of May, and leaving again early in September, this strange bird is but little known to the majority of people, although by no means uncommon in suitable localities.

Its favourite haunts are gorse commons, and moorlands on the edge of woods, especially where bracken grows freely, and in such situations it may be found throughout our islands. The best time to see it is at dusk, when it comes out to capture moths, beetles, and other crepuscular insects which form its chief sustenance. Its flight is silent and very bat-like, twisting and turning with great ease and agility, now and again striking its wings together with a loud clap and uttering at the same time a sharp little whistle. When resting on a branch, which it invariably does lengthways, a curious reeling note or vibrating "churr" is uttered.

No nest is made, but the two white eggs, boldly blotched and mottled with brown and lilac, are laid on the bare ground without any attempt at concealment. The bird sits very closely, and her dull greyish plumage so assimilates with her surroundings that it is almost impossible to see her until she rises and circles round, uttering a harsh "chuck, chuck."

The young, when first hatched, are covered with an ashy grey down, and have, even at this tender age, the large mouth with enormous gape, characteristic of this family. They do not remain in the nest till fledged, but crawl about on the ground. They do not, however, attempt to feed themselves, and are carefully tended by their parents till they are well able to fly, when they at once quit this country to winter in tropical Africa.

The plumage of both sexes is nearly alike, and is ashy grey, streaked and spotted irregularly with brown. The male has a white spot near the centre of each of the three outer primaries, and the two outermost pairs of tail feathers are tipped with white. These white markings are absent in the female. The young practically resemble the female Length 10·5 in.; wing 7·55.

One example each of two other species of this family, the Red-necked Nightjar (Caprimulgus ruficollis) and the Egyptian Nightjar (Caprimulgus ægyptius) have been taken in England. The first named is a native of Southern Spain and North Africa as far east as Tunisia; the breeding-quarters of the other are in South-east Europe, Egypt, Nubia, and Tunisia. In general appearance they both closely resemble our common species; the Red-throated may, however, be recognised by the tawny collar encircling the head, and the Egyptian by the inner webs of the primaries being pure white.

THE WRYNECK Iynx torquilla, Linnæus

Under the name of the "Cuckoo's Mate" this species is well known in our southern and south-eastern counties. Elsewhere in England it is rare or local, and in Scotland and Ireland it is of very irregular occurrence. The name "Cuckoo's Mate" is derived from the fact that its arrival usually coincides pretty closely with that of the Cuckoo, namely during the first week in April, but in other respects it has no connection in habits or distribution with the better-known species. Owing to its dull and unobtrusive plumage, and more especially from its custom of inhabiting gardens and woods, it is not easy to see, though to those who know its note, which is a sharp "qui, qui, qui," its presence will be frequently made known. It feeds chiefly on ants, which it searches for on the ground or on tree-trunks. These are rapidly conveyed to its mouth by a quick motion of its long extensile tongue, which is coated with a sticky mucus, and the rate at which this organ is shot forwards and backwards is almost incredible, and reminds one rather of the tongue in the chameleons and some other lizards. It breeds in the hole of a tree, and the six round white eggs are laid on the wood itself without any attempt at a nest. If the hole be visited during incubation the sitting bird will utter a peculiar hissing noise, and at the same time twist her neck in a most surprising manner. This habit, which is well calculated to make the observer believe the hole to be tenanted by a snake, has given rise to the name of "Snake-bird" as well as the better-known one of Wryneck. The sexes are alike in plumage, the general colour being greyish with dark streaks of brownish black on the nape and scapulars. Throat, upper breast, and flanks yellowish, becoming paler on the belly, with narrow black bars and arrow markings. The young are greyer, and have no yellow or arrow-shaped markings on the under parts. Length 7 in.; wing 3·4 in.

Towards the end of September it takes its departure, but some individuals frequently remain much later, and probably occasionally spend the winter with us.

THE GREEN WOODPECKER Gecinus viridis (Linnæus)

The cheery "pleu, pleu, pleu" of the Yaffle as it flies from one tree to another may be heard in most parts of England and Wales, though in Scotland and Ireland it is almost unknown. It is a moderate-sized and somewhat ungainly bird in its actions, spending its life among trees, though it by no means restricts itself to woods, especially in autumn, when it may frequently be seen ascending some hedgerow tree, with its characteristic jerking motion, the stiff and pointed tail feathers aiding it to cling to the trunk. Its food consists of insects, more especially beetles and ants, which it finds in crevices of the bark, but it often descends to the ground in search of food.

Its flight is direct and undulating, and it proceeds by a series of rapid wing-beats followed by a short falling period, when the wings are half closed. On the ground it progresses by short hops, and when searching a tree for food, it ascends spirally from the base in short jerks, flying off when near the top to recommence its search at the base of another. Early in April it begins to excavate a nesting-hole, choosing for preference a tree destitute of lower branches. A neat circular hole is chiselled out, which is carried in horizontally for some distance, and then turns downwards. No special nest is made, the glossy white eggs, about five in number, being laid on the bare wood.

The young remain in the nest till they are full fledged, and then scatter to earn their own living.

The general colour of the male is olive green, shading into yellow on the rump and becoming greyer on the under parts. The crown and nape are crimson, and there is a malar stripe of the same colour edged with black. The female has less crimson on the head and the malar stripes are black. The young are mottled on the back and spotted on the under parts with blackish. Length 12·5 in.; wing 6·4 in.

THE GREATER SPOTTED WOODPECKER Dendrocopus major (Linnæus)

Although it can nowhere be called abundant, this species is widely distributed in well-wooded districts as far north as Durham, but in Scotland it is a scarce bird, only nesting very sparingly in the south, and in Ireland it is almost unknown. A quiet and shy bird, it is rarely seen, keeping as it does to the higher branches of tall trees, and when possible keeping the trunk between it and any would-be observer. In its food and habits it resembles the Green Woodpecker, though it is comparatively seldom seen on the ground. The call-note is a sharp, short "chik," but it makes also a peculiar rattling sound by rapping its beak against a bough. This sound, which is more often heard in early spring, has been supposed to be made only at that season, but it may also be heard, though less frequently, at other times of the year.

In winter this species is much given to wandering, and every autumn our local birds receive further additions from Scandinavia. It can hardly, however, be considered a regular winter visitor, as such immigrations are largely dependent on the season, and it is only at irregular periods that really large numbers arrive.

The upper parts of the male are chiefly black; the forehead, cheeks, ear coverts, and scapulars are white; nape crimson; wing feathers black, barred with white on the outer webs; under parts whitish; vent crimson. The female lacks the red on the head, but the young of both sexes have the crown red. Length 9·4 in.; wing 5·5 in.

LESSER SPOTTED WOODPECKER Dendrocopus minor (Linnæus)