How Birds Improve in Nest Building.
By William Keith Brooks
WE have long been told that beasts and birds work only by "instinct," and that they never reason and are incapable of any improvement. It is interesting to notice how occasional facts upset the best "philosophy" of the wise. The following article is rare in its statement of facts, and cannot fail to interest every reader:— "You often will meet with the statement in books about birds and birds' nests, that each species goes on, year after year and generation after generation, building its nest precisely the way which has always been followed by its ancestors. It is said that birds build their nests entirely by instinct, and that no improvement ever takes place, but that each bird selects a place for its nest, and gathers the materials, and goes through the process of building in exactly the way which has been followed by thousands of generations. It is also stated that young birds know how to do all this without any instruction, and make their first nest as skillfully as those old birds which have had experience, and have raised several broods of young. These statements are made so often by writers upon natural history, that it would seem as if there must be a good reason for them, and yet not one of them is true. Birds do not always go on building their nests in similar places to those in which their ancestors built, but whenever better places are offered them, they soon learn to take advantage of them; neither do they stick to the same material for one generation after another, but whenever more suitable material is placed within their reach they often learn to use it, so that their nests are much better than those built by their ancestors; neither is it true that they never improve the shape of their nests, nor that the young birds are as skillful architects as the old. "You all know that only a few hundred years ago there was not a barn or a chimney within the United States, unless, perhaps, those singular cliff-dwelling people in New Mexico and Arizona, of whom we know so little, had barns and chimneys. At any rate, we know that on the east side of the Mississippi, at the time when the white men discovered and settled the country, there were no people who knew anything of architecture. The barn and chimney swallows were to be found here then as they are today, but of course they were compelled to build their nests in hollow trees and caves, or any other suitable places which they were able to find. As soon as white men spread over the country and erected buildings, these birds, which had never before seen a barn or a chimney, soon discovered that these places are much warmer and dryer than rotten trees and damp caves, as well as better protected from storms; and it probably did not take many years for the swallows to discover that snakes, and birds, and beasts of prey did not dare to approach such places. These wise birds, then, improved upon the habits of their ancestors, and gave up their old savage life in the woods, in order to share the benefits of civilization. "It seems as natural now for a barn-swallow to make its nest in a barn, as for a catbird to build in a bush or a tree; but it is plain that this has not always been the case, and that these birds have been wise enough to change their mode of life. "It is very certain that a few hundred years ago orioles could have known nothing about string or carpet ravelings, and must have confined themselves to such stringy fibres as can be found in a natural state; and those orioles which build their nests at a distance from houses, still make use of grass, flax, and fibres of silk-weed, and other things which they are able to find; but of course a much stronger and more durable nest can be woven from strong thread and string, and the birds have not been slow to discover this and to act accordingly. "A few years ago Pouchet, a French naturalist, who was then engaged in writing a book upon natural history, wished to have an engraving made of the nest of the common European house-martin. The nests in his collection were nearly fifty years old, and, thinking that the artist would be able to make a much better picture from a new and perfect nest than from an old one, he employed a man to collect a number from the walls of the houses in Paris. "Upon comparing these with the old nests in his collection, Pouchet found that there had been a very great improvement in the architecture of these birds within the last fifty years. He says that the old nests are globular, or forming a segment of a sphere, with a very small rounded opening, just large enough to allow the passage of the birds inhabiting it; and the accounts of all the ancient writers agree in describing this as the form of the nest in their day. The new nest is in the form of the quarter of a hollow semi-oval, this giving three flat surfaces for attachment instead of one, and affording much more room on the floor of the nest. The opening is no longer a round hole, but a long transverse slit, between the upper edge of the nest and the wall of the building to which it is attached, thus allowing the young to put their heads out and enjoy the fresh air, without interfering with the entrance and exit of the parents. M. Pouchet says that, besides the advantages of more room inside the nest, increased facilities for access and greater strength, it is also more secure from the invasion of enemies, and better protected from the entrance of cold and rain, and is thus a decided improvement upon the old form. "Many of the naturalists who have studied the habits of birds with the greatest care have satisfied themselves that young birds are not as skillful as the old. Nearly one hundred and fifty years ago Leroy, a French naturalist who spent his life in studying the habits of the wild animals of Europe, published a book, which has lately been translated into English, on the 'Intelligence and Perfectibility of Animals.' In this book he says that it is impossible that a constant and attentive observer should fail to remark that the nests of young birds are almost invariably ill-made and badly situated. He also shows that the best and most complicated nests are made by those species of birds whose young remain a long time in the nest, and thus have more opportunity to see how it is made. Wilson, the ornithologist, who spent his life in studying the habits of our birds, reached the same conclusion—that there is a very perceptible inferiority in the nests of young birds.—Prof. W. K. Brooks, in St. Nicholas for August.