29 SEPTEMBER 1906, Page 11


October is probably the season of the year when our avine population is the least numerous: Generally speaking, the summer migrants have gone and the winter migrants have not yet come. There are, of course, the nestlings of the year—those, at least, which have not migrated, but are of the resident End—to swell the numbers, and pheasants and partridges have not yet fallen to the gun as numerously as they will fall Boon; but as they fall the winter migrants establish themselves with us, and on the whole, perhaps October is our least populous month, from the avine point of view. The migration of birds is a subject which is full of interesting and difficult problems, and not the least interesting nor the least difficult of comprehension is the question how they find their way. About the admirable accuracy of their movements there is no question whatever. The willow warbler will come back year after year to occupy the same position, in the same tangle of grass and under- growth, as the site for its nest. Others are no less accurate and punctual; but the exactness of this little bird is the more remarkable because of the apparently feeble powers of flight which seem to leave it quite unprovided with the locomotive means required to bring it so unerringly to its goal. While the questions which migration presents are difficult enough of understanding, there is one which transcends all the rest in its obscurity. It is the question which is suggested by the fact, apparently quite well authenticated, that in the case of many species they are the young birds of the year that lead the migration flight. Of course this is the kind of fact which is very difficult of proof. It is open to the objector to say : "How do you know that there are not a few old birds, perhaps the barren birds of the year, taking part in the earliest migra- tion flights of the species, and so giving a lead to the youngsters along a line which has become familiar to them through previous travel F" It is difficult to answer this Objector satisfactorily, because he at once puts his opponent into the position of one who has to prove a negative, and we all know what an uncomfortable position that is. The pros and cons of the whole argument are far too long and intricate to enter into here. All we can do is to ask the reader to accept the verdict of such observers as Gatke and many more that the birds of the year in many cases do lead the migration flight, that some instinct seta as their compass, and that they do not avail themselves of the guidance of any old or barren birds.

No doubt to ask credence for such a statement is to ask a good deal. The explanation sometimes offered, that these birds are led by inherited instinct along the migration lines followed by their forefathers, in some cases pursuing the course of a long-since-submerged river or other visible guiding-line, is an explanation almost as hard of acceptance as the original mystery which it is invoked to explain. Nor does the mystery become any less mysterious, though it becomes more possible of credence, even if not of comprehension, when we consider it alongside of other examples of a like kind with which natural history can furnish us. For it does not stand alone by any means. If it did, we might indeed ask credence for it in vain. The instinct, as it appears to be, which leads animals to direct their course to a certain spot without, so far as we are able to ascertain, any previous hint or indication of guidance, demonstrates itself in several remarkable ways besides that of the migration flight, but in none perhaps more remarkably than in the case of the guanaco, a species of llama of South America, which resorts in immense numbers to a certain place to die. In fact, it seems, from the accounts given by Darwin and by Mr. W. H. Hudson, that all the guanacos of the southern part of Patagonia must resort, when the hour of death approaches, to a certain spot in a certain river-bed which has become a perfect mausoleum of their bones. Mr. Hudson has hazarded a very ingenious hypothesis to account for this assemblage in the common mortuary. He notes, primarily, that it is only the guanaco of the southern extremity of the South American Continent that has this habit ; which is as much as to say that it is a habit restricted to descendants of forefathers who' lived at one time in an

extremely rigorous, semi-Arctic climate. Mr. Hudson con- jectures that among these forefathers the instinct grew up, when the stress of hunger and cold was very dire and they felt its chill setting upon them, of resorting to this sheltered place in the river-bed, where they might find warmth in their own closely collected numbers, and possibly food, which would enable them to outlive the days of extreme rigour. By a continual survival of those which betook themselves to this place of refuge, the race instinct would be formed of resorting

thither when they felt the tides of life running low. This feeling, Mr. Hudson argues, their descendants are likely to experience now at the approach of the hour of death, and in

obedience to it to flock to the same resort. But now it is no longer just a passing spell of extreme cold which they can hope to survive that leads them thither. The death call has come, and they must lay their bones in the common mortuary. It is not "in order to die," as we so frequently say, with a very common error in considering the ways of animals, that the guanaco seeks this place ; it would be nearer the truth if we were to say it was "in order to live." But the most true account of all, no doubt (if the hypothesis is accepted), is that it is with no conscious purpose at all, but in mere obedience to the inherited instinct, that the guanaco resorts to this refuge ; and still the hypothesis, for all its ingenuity, leaves unanswered the question (save as it is answered by the so- called " explanation " of the migration flight) how the guanaco is guided to this shelter of its forefathers from the Antarctic cold. Yet another instance of what appears to be this wholly mysterious guidance is afforded by the well-known habit of the rattlesnakes, in the colder countries of their range, to assemble together in great numbers for hiberna- tion in caves. It seems to be pretty well established that the snakes, on emerging from these caves, cover long distances in their wanderings, that their young are generally born far away from the wintering-place, and yet that these young, although they do not accompany their parents, nor remain with them until the date of hibernation approaches, still succeed in finding their way to the eaves with the greatest certainty.

All these, and many more which might be cited, are instances which tend to show that animals are led or guided, or whatever the word may be which will express most clearly a fact which is really quite obscure, by some force or influence which is distinct from anything that our senses reveal to us. But to say that they prove it would be to say too much. It is extremely easy to fall into the error of saying too much on a subject of this kind. The wildest and most unchecked statements have been made about the faculty of domestic animals—dogs and cats—for finding their way home after transportation by train and so on, and influences beyond our ken have been invoked very freely to account for such wonders. Wonderful things of the kind do happen, but before we invoke unknown influences for explanation we ought to eliminate very carefully those which are well known A dog taken from his home covers a circle of many miles as he runs aimlessly seeking some familiar object, and when he finds that familiar object he may proceed from it to the next, and so on, back to his home, where he is received as a sign that the age of miracles endures. A cat may find its way similarly, and all these are merely adopting the means (except the winged flight) which the carrier-pigeon also uses in his home-coming. About the pigeon itself there has been a great deal of misconception. It has been imagined that, provided a pigeon belongs to the variety which is called carrier or homing, it is enough to liberate the bird at any distance from its native cote, and it will then immediately fly straight home, led by some mysterious force which is beyond human understanding. There is so much in the universe that really is beyond this modest limit that it is quite unnecessary to invent difficulties gratuitously. As a matter of fact, very well known to all trainers of these pigeons, they have to be carefully practised in flights of constantly extending distances along the line in which it is desired to send them eventually, until a chain of landmarks has become familiar to them along the whole course between the point at which it is wished to liberate them and their native home. There is no more mystery in this than in a man's finding his way along streets the features of which are known to him. Lord Avebury and other observers of insects have seen much to lead them to think that it is in the same simple manner that hymenopterous insects find their way back to their homes; they have no special.loadstone. But, yet, after all has been explained which is capable of explana- tion by means which we are ready to call natural, because we understand them a little and share them a little, there still . seems to remain something over and above which quite defies all our attempts at explanation. The psychology of the lower animals is a subject very full of interest, of which a very great deal still remains to be learnt ; in fact, we have hardly made a beginning of knowledge in it. In the search for glimmerings of light we are constantly in difficulties, by reason of our inveterate habit of trying to interpret the other animals' psychical processes by our own, instead of observing them in as objective a manner as possible. It is a subject which requires great patience and a close study, which . can only be the result of genuine intetest in it; but 'the rewards of the study might be conceivably of great price, if only as a means of revealing to us unexpected. possibilities and sympathies in our human selves.