A Bird's Reason


AN appreciative reader, a man of considerable scientific knowledge, inquires whether I have ever made any observation upon birds which would help solve the mystery of nest building. He writes, ‘Have your eyes ever lighted on any evidence of how birds make nests — whether by instinct or by tuition?’ And he further says that in quest of information under this head he wrote to an ornithologist at Harvard who replied that he did not know of any treatment of the subject. ‘All I could learn,’ he continues, ‘was the information derived from an Italian butler in New York who vouched that he had seen a canary make a good nest in the servants’ quarters — a canary that had never set eyes on any other nest, and that had no guidance.’ And so, while it is generally taken for granted that birds make nests by instinct and without instruction, any real evidence on the nature of the process seems to be scarce.

If my correspondent will allow me, I will add a third element to his query and ask, ‘Or by intelligence?’ For, if a bird has to be taught to make a nest, it is evident that the older one had to be taught, and so on ad infinitum till we are forced to the question, ‘Who was the original teacher and inventor? Or was the highly ingenious art of nest making slowly “ evolved ” ? ’

I will say that I do know a little of how nests are built, because a bird and I once built a nest together; and I know what I did and what the bird did. I did not do this as an experiment or with the idea of adding to human knowledge, though it turned out to be rather informing in the end. I will state the facts and the reader may draw his own conclusion. My conclusion was that nest building is not simply automatic. It does not consist of the instinctive performance of a series of steps — step number one and step number two; for if it were that, how could a bird correct my mistakes in nest building and then carry on to a proper result?


Here are the facts. I was sitting at the table eating breakfast and looking out of the window on a very windy day in spring. As you probably know, a robin likes a flat place to build on, and it usually picks out a shelf-like situation. A robin, recently arrived, had chosen the flat top of a cedar fence post near the window. This post had another post nailed to the side of it and sticking up to form an arch of a gateway between my place and that of my neighbor; and this flat top, with the other post forming a little backing, seemed to be just what the robin wished to build on and against.

The wind was so very strong that no straws or twigs that the robin brought would stay where she put them, but would immediately blow away. I was interested to observe that she met this condition by poking the pieces of dry grass or hay down into the cracks on the top of the post. This held them and would serve for an anchorage to weave and fasten to. We have all seen robins build in cigar boxes and in all sorts of protected and shelf-like places; but this robin, when the wind blew her material away, knew how to handle the situation.

Here entered another side of the problem. There were a lot of sparrows about which I had not been able to get rid of; and a pair of these began carrying away the material as soon as it was deposited on top of the post. They came back time after time, while the robin was absent, so that she made no headway at all in spite of her constant work. I saw that in this state of affairs the robin would never get her nest built. And I kept watching even after breakfast was over.

This finally got my ire up. I am a believer in free government and rugged individualism and a square deal to the extent of being left strictly alone; so I decided to shape a nest myself of about the robin size, with plenty of material, and place it out on the post with the edges tucked firmly into the cracks. And then the humor of the situation struck me and my wife. How would the robin act, and what would she think when she came back and saw all that had been done in the few moments since she left?

I shaped a nest of assorted materials — mostly coarse, stiff grass and small twigs. There was some sphagnum moss lying about, which had come around the roots of some nursery trees recently arrived, and I worked this in, together with a few pieces of white string; but I think now that this was very poor practice, because I have not noted that a robin uses such fine, flimsy material in the bulk or body of the nest.

When it was all ready, and good enough to lay eggs in so far as I could see, I watched till the robin had flown away on another trip, whereupon I hastily anchored my nest in place. And then I waited at the window, anticipating the fun of seeing the robin eye the work, and wondering what puzzlement and what final outcome would develop.

The bird came back, and after a very little inspection of my handicraft she set to work and rebuilt the nest right there, without having to go for any more material. She accepted my work as a whole, but corrected mistakes here and there, sewing and stitching till she had quite made it over. A bird’s bill, with a string or piece of grass held near its tip, is virtually a needle and thread. She would take a loose end and poke it right into or through the nest, and take another piece and weave it up into the edge, and so she worked away for quite a while; and of course she had the whole framework finished in a mere fraction of the time it would usually take a robin to build a nest. With this done, she flew away and came back with a little pile of mud on the end of her bill; and she kept this up till the interior had received the usual coat of windproof plastering. Then came the finer lining, the material for which she brought herself, a very little of this being required. A clutch of eggs was laid and a family of robins successfully raised.

These are the plain facts, out of which you may make what you can; and they constitute my only actual experience and technical observation on the art of nest building. As I say, it did not consist of step number one and step number two, and that carrying out of an automatic record on the brain which instinct is supposed to be — always perfect and infallible so far as its specialty goes. I was certainly not infallible; and the bird looked over my work and made it right. And what bird ever had such an experience before — or how often in the course of bird history? Yet she dealt with it.

Of course birds do acquire by instruction some of the things they know; they have a sort of tuition in singing and food getting. Canaries may be taught little refrains with the whistle or flute; and a canary that is brought up in solitude, while it will have a number of native tunes, will not have anything near the repertoire of a bird that has taken lessons from others. Consequently canary raisers send their canaries to singing school, as you might say; they keep them in the company of the cultivated and expert singers until they have themselves become singers of scope. But it is my private opinion, a mere guess, that birds do not receive lessons in nest building.


And now as to the question of evolution of the art of nest building in all its various and ingenious forms.

I have before me the nest of a Baltimore oriole which I had kept for further study and admiration. The cord with which it is tied or suspended to the thin twig of elm is a piece of strong cotton string such as grocers use; and besides this long piece of string woven around the mouth there is not another bit of material in the big pouchlike nest except the down from thistle or milkweed. The bird had searched about, no doubt with endless patience, till it found this necessary piece of cotton string; and, having found that and got the structure started, it went ahead with its weaving of the rounded, symmetrical pouch out of the milkweed down.

Now when this country was inhabited only by the wild Indian, not so very long ago, where did the oriole get the white cotton string? What did it use in place of this strong, flexible, and dependable article of commerce? How did the race of Baltimore orioles come to substitute white cotton grocery string for their original staple of manufacture? And how comes it that an oriole setting to work will search and search until it has found a piece to go ahead with? They certainly know it when they see it; and this looks very much like observation or thought or intelligence. Instinct and evolution are supposed to be processes of very slow growth, things of æons or ages; yet it was only yesterday, as history goes, that there was not a grocer in Wisconsin !

I have said that the oriole’s nest is suspended with the cord; but I might better say that the edge of the nest, the open neck of it, is fastened at one edge to the hanging twig. How does the oriole get that string-bound opening shaken or flung out upon the air, and how does it get the whole thing started?

I had a chance to learn this once when an oriole was building on an elm right near a dormer window; but at that time I was building the house and I did not take time to sit and watch day after day. If I had it to do over again I would let my house wait and find out how the oriole builds her own.

The idea in building on the far and final twig of a pendulous branch of elm is, of course, that the red squirrel cannot approach and steal the eggs. I have seen a red squirrel try this feat, going out farther and farther toward the end from which the nest was suspended on a very thin and hanging twig. The red squirrel would crouch down on his belly on a branch where it was still thick enough to hold him, and stretch and reach to his utmost in order to get his claw on the eggs. But the Baltimore oriole had outwitted him — it could not quite be done.

Now as to the process of evolution. This would consist of rudimentary and imperfect types of nests, and then a gradual advance to a more complex and perfect and specialized type. Well, then, if you were visualizing an imperfect, a not-quite-finished type of oriole nest, what would you leave off? Would you leave off the bottom, or the sides of the pouch, or the string that holds it to the support? It seems evident that an oriole’s nest must be complete or it is no nest at all. How did it evolve? Or was it made that way in the first place?

Right at this point I am likely to arouse a certain type of ‘evolutionist’ — about as opinionated and touchy a person as I know. He takes alarm at once if he suspects you are trying to prove something. He is about as pernickety as the most aggravated sort of Fundamentalist. But I am only concerned with facts, and am willing to follow where they lead.

If the bird learns from its elder, by tuition, where did the original bird learn the art? Where was the intelligence that originated, perfected, designed the various types of nest? And as for ‘instinct,’ what is that but a name for the ability to build a nest and do other like feats?

I have said that except for the piece of string the nest was made wholly of vegetable down. I must make a slight correction.

In the bottom, as support or lining, there is a very little of grayish hair. It looks very much like my wife’s hair. But on taking out a strand and examining it closely I find it is not quite fine enough. I have added this detail of the scant lining for the sake of accuracy.