It will not be forgotten how this bird flew from the point which it had reached on one tree, right down to the roots of another, and ascended from these. The tree-creeper, when it flits from tree to tree, generally does so in a downward direction. If trees were of a uniform height, and if the bird usually ascended to the top, or nearly to the top, of each one in succession, one could see the rationale, or even the necessity, of this practice, for the tree-creeper does not—at least not usually—descend the trunk. But in a wood, the top of one tree may not represent half the height of another, and, moreover, a tree will often be abandoned by the bird when it has reached only a moderate height, or is still quite near to the ground; and it is not so easy to see how, under these circumstances, the above-mentioned habit should have arisen. But, now, if the forerunners of the tree-creeper had been birds accustomed to hop about on the ground, and to peer and pry amongst the projecting roots of trees, and if they had, from these, gradually ascended the trunk, getting back to them at first quite soon, but making longer and longer and more and more accustomed excursions, then we can understand how this habit might have become—as one may say—rooted, so as to continue after there was no longer any particular advantage in it. Now, however, it is beginning to weaken. I have on several occasions—which I duly noted down at the time—seen a tree-creeper fly from one tree to another, upon which it clung, in an upward direction. I have little doubt that what is now still a habit will come to be a preference merely, and that, in time, even this will cease to be discernible, and the bird be guided simply by circumstances.
It is said that the tree-creeper never descends the tree it is on, and, also, that it generally proceeds in a spiral direction, by which, I suppose, is meant that the line of its course winds round and around the trunk of the tree. This last, however, has not been quite my experience. I have watched the bird often and carefully, and I should say that a true spiral ascent by it is decidedly exceptional. Often one has alighted upon the tall stem of a Scotch fir, on the side away from me, and never come round into view at all. On other occasions, after some time, I have seen its tiny form outlined against the sky on one or other side of the trunk, considerably higher up, and then, again, it has disappeared back, or flown to another tree. This can hardly be called a spiral ascent, and I have seen no nearer approach to one. Often, too, I have seen it mount quite perpendicularly for a considerable distance. To me it appears that the tree-creeper recollects, occasionally, that he ought to ascend a tree spirally, and begins to do so, but the next moment he forgets this tradition in his family, and creeps individually. One might expect, indeed, that insects or likely chinks for them would act as so many deflections from the path of spiral progress, which, as it seems likely, may have been originally adopted for the same reason and upon the same principle that a road is made to wind round a mountain instead of being carried up the face of it. But how is it, then, that the wren and the blue-tit ascend tree-trunks perpendicularly? for one would have thought that the less au fait a bird was, the more would the advantages of an easy gradient have forced themselves upon it. But these birds are still—sometimes, at any rate—aided by their wings, so that it would seem as though their tree-creeping had been developed, or was being developed, as an adjunct to tree-fluttering. Now, as it appears to me, though it might be easier for a bird to creep up a tree by going round it, it could more easily flutter up it perpendicularly,[20] in the way I have described, and, if so, we can understand a bird that is only in process of becoming a tree-creeper, commencing, as it were, at the most advanced end. For it would first have fluttered up perpendicularly, then have both crept and fluttered so, and finally, when it could creep without fluttering, it would do so at first on the old fluttering lines. Then it might begin to adopt the spiral method, but as the effort required became less and less, and structural modification—as seen, for example, in the shape and stiffness of the tail-feathers of the tree-creeper—came to its assistance, this would cease to be a help, and become a habit merely, and when once a habit has lost its rationale, it is in the way of being broken, even in good society. Thus the perpendicular ascents of the tree-creeper may be the final stage in a long process, and the return in ease to what was before done in toil.
[20] Or rather no particular difficulty would be experienced, so that the shortest course would be the best one.
The tree-creeper is assisted in its climbing by the stiff, pointed feathers of the tail, which act as a prop, and also by its small size, which may possibly have been partly gained by natural selection. The great green woodpecker is possessed of the first of these advantages, but not of the second, and it is, I believe, the case that he much more adheres to the spiral mode of ascent than does the tree-creeper, who, as it seems to me, has almost discarded it. It would be interesting, therefore, to observe if the smaller spotted woodpecker shows a greater tendency to deviate in this direction; but I have had no opportunity of doing this.
With regard to the other assertion—namely, that the tree-creeper never descends the trunk of the tree—this is at least not true without qualification, for I have seen it do so backwards, with a curious and, as it seemed to me, a quite special motion. It was quick and sudden, carrying the bird an inch or so down the trunk, when it ceased and was not repeated: a jerk, in fact, but of a much more pronounced character, made thus backwards, than any of the little forward jerks, in a toned—one might almost sometimes say a gliding—succession, of which the ordinary "creeping" consists. The first time I saw this action (to dwell upon) it constituted a perpendicular descent, but my eye was not full on the bird at the moment, so that I only observed it imperfectly. On the second occasion I saw it quite plainly, and this time the bird jerked itself sideways as well as downwards, stopping in the same abrupt manner, though whether it made two short quick jerks or only one, I could not be quite sure of. I think it was two, but that only the last one gave the jerky effect. It would thus seem that the tree-creeper might really progress in this way, for some little while, if it wished to. The tail must almost of necessity be raised, or the stiff, pointed feathers would catch in the roughnesses of the bark; but, either from the quickness of the action, or the slight extent to which it was lifted, I did not notice this.
I have also seen the great green woodpecker make exactly this same motion, downwards and backwards, on the trunk to which he was clinging, so perhaps all true tree-creeping birds may be able to descend in this fashion, should they wish it, though to do so head first may be beyond the power, or rather the habit, of most of them. This, certainly, I have never seen the tree-creeper do, but I should not be at all surprised were I to, some day, and in describing the habits of any bird, "never"—excepting in extreme cases—is, in my opinion, a word that should never be used.
The tit, however, though only an amateur tree-creeper, does, as we have seen, descend the trunk head downwards, showing, to this extent at least, a superiority over a much greater master of the art. But here we have the flutter, whether helped out by the use of the feet or not, and we can imagine that, as the bird became more and more a true creeper, and used the wings less and less, he might cease to descend, and only creep upwards. It must, however, be remembered that all the tits are accustomed to hang head downwards from twigs and branches in an uncommon degree, so that a member of the family, developing along these lines, might find it easier to descend the trunk, or make greater efforts to overcome the difficulty of doing so, than a bird whose habits in this respect were less pronounced. Tits perch more generally amongst the higher branches of trees, and have no particular habit of hopping about the ground or creeping over and about the tangle of a tree's projecting roots, which I have often watched wrens doing. Those which I saw tree-creeping did not fly—or at any rate I did not notice that they did—from the tree they were on, so as to alight upon another at a lower elevation, but they were hardly systematic enough to let one judge properly as to this. The wren, however, both in this respect and in its general façons d'agir, had a striking resemblance to the tree-creeper, with which bird—if I read the systematic tangle (I mean in print) aright—he is more closely related than are the tits.
"Howsoever these things be"—I fear I have dwelt too long upon them, but whole books are written upon a war or even a battle—the little tree-creeper is a very delightful bird to watch. Sometimes, on inclement winter days, one can come very near him, very near indeed, and almost forget the cold, the rain, the sleet, in his active busy little comfort. To see him then creeping like a feathered mouse over some stunted tree-trunk, and insinuating his slender, delicately-curved little bill into every chink and crevice of the bark—so busy, so happy, so daintily and innocently destructive! His head, which is as the sentient handle to a very delicate instrument, is moved with such science, such dentistry, that one feels and appreciates each turn of it, and, by sympathy, seems working oneself with a little probing sickle that is seen even when invisible, as is the fine wire or revolving horror in one's tooth, whilst sitting in the dreadful chair. After watching him thus—almost, sometimes, bending over him—I have broken off some pieces of bark, to form an idea of what he might be getting. A minute spider and a small chrysalis or two would be revealed, but there were, generally, many cocoon-webs of larger hybernating spiders, whilst empty pupa shells and other such debris suggested "pasture" sufficient to "lard" many "rother's sides." And again I wonder why there are not more professional tree-creepers, why countries so rich and defenceless are not more invaded, in the name of something or other high-sounding—evolution will here serve the turn. But, in spite of this abundance, the tree-creeper does not quite confine himself to searching the bark of trees, for I have seen him, on one occasion, dart suddenly out and catch a fly, or other insect, in the air, returning immediately afterwards to his tree again. To my surprise, I cannot find this in my notes, but, as my memory is quite clear upon the point, I mention it. This is another method of procuring food, which, as an occasional practice, is widely disseminated amongst our smaller birds, and here again one wonders why it has only become a fixed habit with the fly-catcher. However, I have seen a male chaffinch dash from the bank of a river and catch may-flies in mid-stream, sometimes a little and sometimes only just above the surface of the water, several times in succession, so that, in this case also, we see the possible beginnings of another species.
I have forgotten to admire the tree-creeper—I mean as a thing of beauty. To do so is a very refined sensation, he is so neutral-tinted and half-shady. One is an æsthete for the time, but the next blue-tit dethrones one, for one has to admire him too, and he, with his briskness and his Christian name of Tom, is hardly æsthetic. The hardiness of these little creatures—I am speaking here of the tits, but to both it would apply—is wonderful—quite wonderful. They are downy iron, soft little colour-flakes of nature's very hardest material. It is now—for I select a striking example—the most atrocious weather, a howling wind, and sleet or sleety snow that seems, as it falls, to thaw and freeze upon one's hands, both at the same time. Later it becomes almost a storm, with more snow. It is, indeed, a day terrible to bird and beast in the general, as well as to man, yet, through it all, these tiny little bits of natural feather-work are feeding on the small February buds of some elms that roar in the wind. Wonderful it is to see them blown and swayed about, with the snow-flakes whirling about them, as they hang high up from the extremities of slender twigs, playing their little life-part (as important in the sum of things as Napoleon's) with absolute ease and well-being, whilst one is almost frozen to look at them. One must think of Shakespeare's lines about "the wet shipboy in a night so rude," but what a poor mollycoddle was he by comparison! Later they will sleep—these robust little feathered Ariels—to the tempest's lullaby, above a world all snow, and with frozen snow the whole way up the trunk of every unprotected tree, on the windward side. Now it is dinner, with appetite and entire comfort "in the cauld blast."
What insects are in these tiny little new buds, or are there insects in each one?—for these tits browse from one to another and seem equally satisfied with all. Yet it is authoritatively stated that they eat only the insects in buds, and not the buds themselves. In watching birds, however, as in other things, one should be guided by a few simple rules, and one of the most important of these is absolutely to ignore all statements whatever, without the smallest regard to authority. Everything should be new to you; there should be no such thing as a fact till you have discovered it. Note down everything as a discovery, and never mind who knew it—or knew that it was not so—before. You may be wrong, of course. So may the authority. But what makes authority in a matter of observation?