The thoughts of birds and beasts are probably few and simple. Yet it is unlikely that they are able to communicate all their thoughts to one another, because the language they possess consists of a few monosyllables, by which they can express only elementary feelings such as pain, anger, fear, hunger, and the presence of food.

Some animals possess a much larger vocabulary than others. Dr. Garner, who went to Africa to study the language of his Simian brothers, found that the average monkey was able to emit only about seven cries, but the vocabulary of the highly intelligent chimpanzee comprised twenty-two separate calls.

According to Mr. Edmund Selous, the rook is really in process of evolving a language. He records no fewer than thirty-three distinct sounds he heard rooks utter, and states that this is but a small page out of their vocabulary. Nevertheless, he is compelled to admit that only in few cases was he able to connect a note with any particular state of mind.

The articulate language of animals is a language of monosyllables, a language composed almost entirely of interjections. Such a language, while very expressive as far as it goes, does not go very far. And the question naturally arises, does it go sufficiently far to meet the needs of the various species, or have they some means of communicating with one another other than by sounds? It is very tempting to believe that they have, that they are able to transmit thought to one another in some way. It is only on the assumption of brain waves that one can explain the soldier-like evolutions which flocks of birds sometimes perform in the air.

I have often wondered how those species of birds, of which both the cock and hen take part in the nest-building operations, select the site. The matter is, of course, simple when only the one sex constructs the nest. But how is the site selected when both sexes build? It is tempting to believe that they discuss the matter, that the hen says to the cock, “Now, James, my dear, it is necessary for us to build a nest without delay: come, let us select a secluded spot wherein to build”; and to picture the little birds hunting about together and criticising the sites each selects. Nevertheless, I think it most unlikely that any such discussion takes place. Nest building is largely instinctive. In the case of the first nest it is improbable that the little builders quite know what they are doing, and I do not see how, before the nest is begun, they can have any idea of what it will look like when it is finished.

It is possible that birds agree as to the site without any discussion or without any communication. Let us suppose that a pair of bulbuls have mated. Suddenly one of them is overmastered by the nest-building instinct which has hitherto lain dormant. This particular bird is impelled by some irresistible force to seek out a site and then forthwith to begin to build the nest. The nest-building instinct of its mate, which is dormant, is at once awakened by the sight of its spouse collecting material. When this happens the second bird begins collecting, and is content to work at the structure already commenced by its mate. Assuming the correctness of the suggestion that the nest-building instinct does not, as a rule, become awakened simultaneously in a pair of birds, what will happen in the exceptional cases when the instinct does awaken simultaneously? When this happens, it is my belief that each sex commences to build a separate nest. When one of the pair discovers what its mate is doing, it, of course, gets angry and scolds it. The other returns the compliment. Probably the next step is that each examines the handiwork of the other and thinks very little of it. Possibly at first each refuses to yield to the other, or the one whose nest is the least advanced leaves this in favour of the other, or—a third alternative—the stronger bird may attack the weaker and compel it to desert its nest.

This, of course, is pure conjecture. But it is in accordance with the fact that numbers of nests are commenced which are never completed, and which, indeed, never progress very far. There are at present in my verandah two nests belonging to bulbuls which have been left after about three hours’ work was put into them. Several explanations of this phenomenon are possible. Each bird may have commenced a separate nest, and so one was deserted; or the site in question may have been found to have some fatal defect, consequently the nest has been given up; or the birds have been scared away or killed. The last alternative is the least likely, and I am inclined to believe that the first explanation is the true one.

I recently read in Country Life an exceedingly interesting account of the nest-building operations of a pair of wagtails. The account is brief and has so important a bearing on the subject we are discussing that I take the liberty to quote at length:—

“From the cover of a riverside cottage,” writes Mr. Alfred Taylor of the grey wagtail in England, “I saw two birds repeatedly fly to a rocky ledge both with nest-building material in their beaks. It was soon evident that the male wagtail had selected one nest and the female another place a couple of yards away. The former for some time took no notice of the doings of his mate, and they both continued to gather materials into their selected places. Suddenly he flew to her position and commenced removing her material to the place where he thought the nest ought to be. Trouble seemed to be brewing in the family, especially when she still persisted in carrying dead grass to her site. In the end the cock bird lost his temper, flew to her ledge, and viciously attacked her, knocking off the ledge all evidence of her efforts at building. She flew away, and for a couple of hours remained perched in a tree and sulked, evidently much upset at her chastisement, not taking the slightest notice of overtures of peace from her mate. As the deadlock seemed likely to continue I departed.

“Two days later I was round again, eager to see how the difference had been settled, if at all. To my great surprise, I must confess, the male bird had given way to the female, and the nearly completed nest was on her chosen site. A close examination of the two places showed that the judgment of the male had been at fault. Where he had erred was in not detecting the presence of mice; it was quite impossible for these destructive little animals to reach the spot selected by the hen.”

Here, then, is a case of the cock having selected one site and the hen another. Had they gone about choosing a site in company and disagreed upon the place, it is hardly likely that the cock would for some time have taken no notice of what the hen was doing; he would surely have set his foot down at once. The fact that at first he took no notice seems to show that at the outburst of what I may perhaps call the fury of nest-building the cock had eyes for nothing but his work. Again, when the cock did assert his authority, he apparently did not argue with the hen. He simply knocked her and her handiwork off the ledge—a rude but forcible, if inarticulate, method of expressing his feelings.

It may be asked, how was it that the birds agreed to the change of site if they were not able to communicate with one another? Here, again, we must wander into the field of conjecture. It must suffice that it is possible to explain the change of tactics of the cock without assuming any communication between him and his mate. Let us suppose that while she was sulking, and he was working, a mouse appeared on the scene. This would alarm him, and possibly the instinct of flying from enemies, that the appearance of the mouse called into play, would cause him to desert his nest, and perhaps he too began to sulk. Then the hen, once again overcome by the nest-building instinct, recommenced her work, and when the cock followed suit he left his useless site and worked at hers.

Investigation into the extent to which birds and beasts can communicate with one another is as difficult as it is fascinating. It is one of those subjects of which probably but little can be learned by systematic experiment. The casual observer is as likely to throw light upon it as the man who makes a special study of it. A chance incident, such as that observed by Mr. Taylor, throws a flood of light upon the subject. It is not until we have a large number of such observations on record that we shall be able to acquire some definite knowledge of the extent to which birds and beasts can, and do, communicate with one another.