BUILDING BIRDS' NESTS.
APRIL is to our birds the time of great and happy achievements. The building of the nest embodies for these intellectual and 1:esthetic creatures all that is greatest in their life. Courtship and the rearing of the family stand for love and duty. The nest-building combines both, and adds hope, imagination, the excitement of a joint Purpose, and the quiet satisfaction of intelligent success. They are making something, often a work of art, generally a
work which takes thought, sometimes one of exquisite fancy and elaboration.
Dull birds, dainty birds, deft birds, clumsy birds, enjoy and take a pride in it, with different degrees of intensity. Some are very simple, others very knowing. Some work with the simple, sincere, and skilful sympathy of a lady at her embroidery frame, some with well-meaning awkwardness, in which goodwill makes up for want of taste. After the Easter gales, when the rough winds were still tearing loose chips and flakes from the serpentine rocks of the Cornish Chersonese, and driving the foam-froth from foot to summit of Pradanack Head, the cormorants were building their rude nests 100 ft. below on the gull rock of Mullion Cove. Cormorants are the most awkward and ungainly of all nest-builders. They are only in their element on and under the waves, and can scarcely walk on land. Consequently, gathering nest-stuffs is a hard and puzzling business. Yet some twenty cock cormorants were hard at work, bringing dry untidy wisps of seaweed and dead rock-plants to their wives, who sat on the nests and arranged them. As all the world knows, cormorants carry all other commodities, which in their case mean fish, inside by swallowing them, and then disgorging. These dry weeds cannot be swallowed comfortably, and have to be carried trailing from the beak. In this case they were gathered on Mullion Island, when the birds came lurching and drifting in on the gale, and then made staggering tacks on to the sharp peaks of serpentine, on which they alighted with straddling legs, and handed over the stuff with many endearments to their waiting wives. A week later came a burst of spring, and the small and delicate warblers came over the sea the very first night. Next day they were in the deep little combos near the sea, catching flies, breaking into short bursts of song, or practising under their breath. So far as we know, most of these birds come to some ancestral spot where one, or both, of them has nested the year before. It does not matter whether it be the louvred ventilator over the brewery copper at Chiswick, where a pair of swallows nested for twenty years, or some romantic little riverside in Devon, there they come unerringly. What joy and excitement must be theirs when they hasten to examine their old quarters, and to see how near to last year's site they can make their nest this spring! Generally they are credited with great cunning, because they are so seldom seen at work. The real reason is that they are generally in such a hurry to begin that they are tired and have finished for the day two hours after dawn. After a very cold, wet Easter, like that of this year, the first burst of spring makes them so eager to complete the house that they cannot bring themselves to stop, even when the day is far spent and human eyes are watching them. It is part of bird conscience not to go to the nest when a possible enemy is looking. But in many places in England birds are now already learning that man is no longer an enemy, and the joy of architecture overcomes inherited prudence. In the beautiful Devon valley of the Sid, above Sidmouth, the hot sun which opened every primrose bud till the green hillsides looked like starred brocade, and gilded the orchards with daffodil embroidery, set every little bird to nest-building- The robin, the wren, and the hedge-sparrow, of the birds that stay, and all the little warblers, among birds that come, were busy, working overtime. In this happy valley they have long been protected by common consent; but even so their confidence was unusual. From a wicked old crow who flew down from the furze brake above with a small snake in his beak to the latest arrived whitethroat or cbiffchaff, the) regarded not man, or his presence. The wrens were the busiest of all. In the thick hedges of the scented lanes, by the banks of the shining Ski, under the ivy covered bridge, and along the iris-set streamlets that flow into it, the little brown birds were working as busily as bees. One pair were carrying moss to the very roots of an oak, not two feet above a tiny brooklet. A wren carrying moss does not look much larger than a humble-bee, and its burden is not greater than a pinch of thistledown. But there is a directness and purpose in the flight of the little bird never seen at other times. When feeding its young the wren hops on to a bough near and calls to them. When building it flies straight into the nest, as if shot from a catapult. This nest was so well hidden that when once built no one will ever find it, unless the bird betrays it. Another pair of wrens were flying back- wards and forwards across the river, building in the bank, below which the trout were lying. The cock bird found time
to let off a song, flying to the top of a hedge, between his
journeys, but his mate was far more industrious and sedate. The wrens' nests were half finished, but still wanted the lining. Close by the first wrens' nest a tiny chiffchaff was fidgeting about with a fragment of valuable building material in her beak. Scarcely larger than the wren, and far more fragile,
this little bird, fresh from the Nile Valley or the marshes of the great African lakes, was putting together the fabric of her home in this ancestral bit of Devonshire hedge, in. which her forbears had perhaps built for. generation after genera- tion. The bird had probably come from some uninhabited land, for she showed no fear of the, human beings who were looking at her from three yards off, but only the instinctive reluctance to disclose the place of the nest which every small bird feels even in the presence of other birds. It hopped from branch to branch, sometimes laying down its bit of leaf and singing, but always keeping at a certain radius from the • bushy bottom of a hazel clump. Soon its eager- ness to go on with its delightful task got the better of its nervousness, and it flew down and disappeared at the bottom of the hazel bush. When disturbed it flew out again, dis- closing the domed nest, well advanced, but so cleverly hidden that it was difficult to discover even when its position was known to within six inches. Below the bridge at Sidford, where the river flows fast and clear through the rich meadows, a pair of hedge-sparrows were building in a bramble bush over- hanging the water. Opposite was a thick hedge, from which they were fetching all the material. It was possible both to take notes of the number of visits paid to the nest, and of the time spent in arranging the material. The nest was fully shaped (the edges of the cup being complete) and built mainly of- moss with a few leaves woven in. The fine work of lining it had yet to be begun. This is probably done by one bird sitting inside, while the other brings the hair which lines it. Butt at the stage at which the building had arrived both birds were at work. The speed at which they fetched material and built was remarkable. They brought six bundles of moss in eight minutes, and the longest time taken to work-in the nihterial was one minute and a half.
The fact least understood in the history of bird architecture is the reason why they select such very different building. materials. There is no obvious reason why birds of much the same size, and living in the same parish, should not make similar nests, or nests of similar material. Yet many do not, but choose matter as different as moss and mud. As builders, probably the most intelligent are those which have learnt to use two different materials, one for structure, the other for lining. Then comes the curious fact that different species reverse the order in which these are used. The martin makes a nest of mud and lines it with grass and feathers. The thrush makes a nest of grass and moss, and lines this with mud, or, rather, with cement of cow-dung and rotten wood, which the bird manufactures, just as a Boer makes the floor of his house of the same stuff. The blackbird works mud into the structure, and lines this with fine grass, and the nuthatch often makes very little nest at all, but plasters up the superfluous part of the entrance with fine cement. The return of birds for ages to the same nesting place can be explained on more than one supposition. But is it yet known how astonishingly far back their memory goes ? It is pretty certain, for instance, that the line of heaths and stony plains which runs along the hinterland of Suffolk and Norfolk, from Mildenhall to Thetford, was once the border of a sea. Shore plants still grow there which are now only found by the sea, and insects peculiar to the same tracts. That sea disappeared ages ago. Yet the little ringed plovers, which once bred by the margin of this prehistoric sea, still go there regularly to nest, though the whole breadth of Norfolk lies between it and the ocean.
Can any one who has watched birds building fail to believe that this is an acquired habit, and that something more than the mere capacity for making a nest has been transmitted? It will be found that in nearly every case they make such a nest as is best suited to the needs of their young ones, and that its construction is no more automatic than the building of a summer cottage. The birds are conscious, intelligent actors all along. They often try three or four sites before
fixing on . the final one.- (Wrens are particularly given to. these experiments, and so are rooks.) They conceal them with admirable art, and often adapt the structure of the nest to such concealment. When it is finished they often add decora- tion for mere testhetie pleasure, though this is entirely in the taste and discretion of individuals. Even golden eagles have been known to attempt rude ornament by carrying sacks or strange roots to their nests, and the reed-warbler to adorn its. nest outside with kingfishers' feathers. These are marks that the birds are still progressive, the surest evidence that they are not automatic.
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