The Zoologist/4th series, vol 6 (1902)/Issue 737/The Birds of Sark; and Variation in Song

by Henry Eliot Howard

 

THE BIRDS OF SARK; AND VARIATION IN SONG.

By H.E. Howard.

 

I arrived at Sark on March 1st, having sailed across from Guernsey, a distance of about eight miles. Owing to the state of the tide and wind, the landing had to be made at the port of Havre Goslin, which landing-place consists of an iron ladder fixed on the cliffs, perpendicular for some distance, with a fairly steep climb at the end of it. The island is three and a half miles long by one and a half broad, and is encompassed with vertical cliffs two or three hundred feet high. Part of the land is cultivated, and part kept for grazing. The chief feature, however, is the number of valleys running down to the edge of the cliffs, valleys, which, for the most part, are covered with whins, and which account for the great number of stone-chats to be found there.

I was too early to see if the island was visited much by migrants, but I noticed one or two movements. On the 4th, flocks of Green Plover were passing the south end of the island, heading towards the east; the weather was fine at the time, with sea fogs in the morning. On the 11th, while walking near the cliffs facing south, I was attracted by a quiet note, very much like that of a Goldcrest, but sufficiently distinct to arrest attention. After waiting for a short time, the bird appeared out of a dense mass of bramble, and I had the pleasure of recognising a Fire-crest (Regulus ignicapillus). I watched this bird at different times for two days, often within a few feet—never more than twenty-five yards away. The plumage was beautiful, evidently full breeding, the golden hue on the nape and sides being especially bright. The weather had been fine and warm with sea fogs in the morning, and a slight wind from W.S.W. On the 12th, a single Wheatear appeared, and also on the same date I flushed a Woodcock amongst the gorse on the east cliffs. The number of Stonechats kept increasing daily; I noticed no old males among them. On the 12th, also, the Kittiwakes were round their breeding haunts; on the 13th, Razorbills appeared, and on the 17th Guillemots.

I was again struck by the excessive variation in the notes and songs of certain species as compared with my own county—Worcestershire. This variation I have previously alluded to in these pages. I thought, however, it would be as well to endeavour if possible to determine wherein the exact difference lay—whether in the pitch or arrangement of the song, or both. This was difficult, as to achieve such a result it was necessary to carry in one's mind the exact representation of the song as sung elsewhere. I found that the arrangement of the song—by arrangement I mean the order in which the various trills and single notes are placed, for it will be noticed that the song of most birds is composed of various little "snatches," each one of which practically constitutes a song in itself—differed to a great extent from the same song in Worcestershire, and when first heard appeared to differ in toto. I will take two examples, and by comparing the arrangement of the song of these two examples as sung in Worcestershire and Sark, will endeavour to point out the difference as it appeared to me. The two examples are the Great Tit and the Wren, and I take these because in them the variations were most striking, and, therefore, more easily defined.

The song of the Great Tit in Worcestershire consists, as a rule, of two notes, the one uttered last a full note higher than the first. In Sark it was very different, the first note often being uttered three, four, or more times, and the last note once; occasionally the first note was uttered alone, repeatedly, for some time.

The song of the Wren in Sark differed from other Wrens more than the preceding example differs from its respective species, and is more difficult to explain. The song is shorter, and certain parts usually found in the song of the Wren are altogether absent.

The whole subject of bird song is one of which we are profoundly ignorant. How few of those who profess to be ornithologists are able to distinguish different notes! One would think that what is known as a "good ear" is a sine quâ non, but this I cannot believe, having frequently noticed that those who are musical are unable to distinguish different songs as readily as those who are not. I feel convinced that it is one of those things which is possible for anyone to learn with patience and close observation. We notice the same ignorance with regard to the appreciation of the beauty in the form of a bird. But can we wonder at this when even artists, whose powers one would think were altogether trained to appreciate that which is beautiful in form of every description, fail to appreciate that which is beautiful in a bird? That one has to be educated to beauty we know; but the same beauty of form, which for generations has been worshipped in the perfect human body, is to be found amongst all creatures in nature by those who seek for it. And yet I feel tempted to say that a naturalist without these two gifts—namely, the understanding of their language, and the appreciation of their form, which undoubtedly they understand amongst themselves as readily as their language—cannot be called a naturalist in the highest sense of the word. But I am digressing.

What are the causes of this variation of song? Is it due to some cause local or temporary, or does it depend on some general law which governs the whole animal kingdom? We naturally turn our thoughts to the human language and the human voice, and it appears to me that we have here somewhat of an analogous case. It is, I think, an admitted fact that dialect is due to climatic influence, and, again, that a damp or wet climate has the effect of relaxing the vocal chords, and thereby lowering the pitch. Does this apply to birds? Dialect perhaps expresses this variation better than arrangement. I noticed in Sark that the song and call notes of certain species were uniformly lower than in the county of Worcestershire. Among the most striking were the call notes of the Blackbird and Chaffinch, and the songs of the Great Tit and Wren. This phenomenon I had previously noticed in the west of Donegal, and having occasion to be there shortly afterwards, I made special observations on this point, and found the same thing in the Blackbird, Chaffinch, and Wren; and in addition amongst the following species: Corn-Bunting, Yellow Bunting, Sedge-Warbler, Whitethroat, Swallow, Blue Tit, and Coal-Tit. It has always been late in July when I have been there, otherwise I have no doubt I should have found it to be the general rule amongst many classes of birds.

I may here say that by the word "call notes," I refer to everys note belonging to a species thai is not actually the song, although they are not by any means in a number of cases call notes in a literal sense. The climate in Sark and in the west of Donegal are much the same. The rainfall of both is above the average; both are subject to bad sea fogs from the Atlantic, and are therefore very damp. On the other hand, the climate of Worcestershire is peculiarly dry, the rainfall being much below the average. Looking, then, at this fact, that a lower pitch corresponds with a damp climate, and a higher pitch with a dry climate, I think I am justified in coming to the conclusion that clmate exercises a certain influence on the pitch of the notes and songs of certain species.

The dialectical variation is more difficult to explain, and my observations up to the present time are, comparatively speaking, so small, that perhaps I am hardly justified in forming any definite conclusion. The great difficulty in any researches on this point appears to be this—that all observations must be carried out by the same person; and to compare, except on general lines, with anyone making similar investigations is almost a practical impossibility. At first I was inclined to think that the song was more highly developed, or the reverse, in certain districts than in others, and that as a result of there being a scarcity of one sex or the other, sexual selection might exercise considerable influence in this direction; but on finding, after making further investigation, that migratory species were subject to this change, any theory with regard to sexual selection acting in this manner becomes impossible, and we must, therefore, look to some other cause for an explanation. I found that the song of the Whitethroat on the shores of Loch Lomond differed very much from anything I had previously or since heard. Again I noticed the same change in the call note of the Chaffinch in Inverness; and I now feel convinced that there are as many dialects amongst certain species as there are amongst human beings. I am inclined to think that the explanation will again be found in climatic influence, and that these dialects are in a great measure due to the lowering of the pitch. Take, for instance, the song of the Wren in a damp climate. When listened to very carefully, it will be be found that the parts that are absent, as compared with a dry climate, are those where the high notes are introduced. I do not mean that the song is not as beautiful; for I have listened to Wrens in Donegal singing quietly, whose notes, certainly not many, for fulness and richness of tone, were equal to the finest notes of the Blackcap. The same phenomenon applies to the song of the Whitethroat.

Different species appear to be subject to this climatic influence in different degrees of intensity. For instance, the variation to be found in the song of the Buntings is very small; I found great difficulty in detecting any variation at all in the song of the Yellow Bunting. The same thing applies to the song of the Tits, the Coal Tit having the least variation. On the other hand, the variation in the song of the Warblers—Wren and Blackbird—is most marked, that in the Whitethroat and Sedge-Warbler being very striking.

These facts seem to point to the variation being proportionate to the development that has taken place in the song of a given species, and I think it can be readily understood that the most highly developed, and, therefore, most sensitive, musical instrument would most probably be subject to this climatic influence in the greatest degree.

There is another phase of bird song which might be confused with this dialectical change, namely, the song of the immature males. The males of probably all species do not get their full song for some years, in the same way that they do not really get their full plumage—I think it very probable that the two correspond; but this song of the immature males differs rather in the direction of fulness and richness of tone than in any actual change of the song, and is very easily distinguished from this dialectical change.

My observations in a damp climate have always been made either in March or July. I think that a close study of the migratory species on their arrival in this country would, by settling certain difficulties, throw some light on the whole question. Is this change to be found immediately on their arrival, or does it increase as the season advances? Is it permanent, or only temporary? The difficulty, as I mentioned previously, is that it is impossible to compare notes with anyone making similar observations, and it is also obvious that it is quite impossible, where so many dialects probably exist, and where so little is known about any one of them, to fix any standard. I would, therefore, suggest that comparisons should be made under as diverse conditions as possible—that is to say, between very wet and very dry districts, or between districts inland and districts on the coast. If it can be proved that this variation exists among certain migratory species immediately on arrival in this country, it will be necessary to follow them into their winter quarters. For, supposing a dialect is inherent in any one given species (which at first seems almost incredible), we should expect to see some signs of it in their said winter quarters. On the other hand, if we follow them and again find new dialects and new gradations of tone, or if we find on their arrival in this country that there is no immediate variation, but that it increases as the season advances, we shall have strong evidence that in some measure at least it is directly due to climatic influence.

I have shown that so many and such distinct variations do exist, and it seems only reasonable to expect that some of these variations, amongst those species which are resident, will become hereditarily attached to the male sex—for if they did not it would be subversive of the theory of sexual selection, a theory which must be admitted by all those who have studied certain species, in whom the vocal powers are excessively developed while courting—consequently species with a certain variety of song will exist in a small body and often breed together, and as a result the development from a dialect to specific song must in time ensue. It may be argued that it is impossible for a variety of song amongst individuals of any one species to have any connection with the origin of song in separate species; but I can see no more difficulty in believing, except to those, if there are any, who still look upon species as immutable, that through the vast ages that have lapsed, during which species have developed, a specific song may have become attached to a certain species through the action of sexual selection on varieties resulting from climatic influence, than I can in believing that species themselves have been evolved.

When we reflect on these variations of song, we can easily understand what mistakes have arisen, and probably will arise, as a direct result of the same; on the one hand, species recorded erroneously in certain districts, on the other hand, species overlooked. The call notes and songs must always be the guiding factor to the ornithologist, as by them alone is it possible to recognize new species, and judge the movements of those that are well known. To those who are aware of these variations of song, and who are able to recognize them, there can be very little fear of mistakes; but to those naturalists who either cannot, or who have not taken the trouble to learn the notes of every species with which they have come into contact, the possibility of mistakes from the above cause must be very great.

The following is a list of all the species that came under my notice during the fortnight I was on the island:—

Turdus viscivorus, T. musicus, T. iliacus, T. pilaris, T. merula, Saxicola œnanthe, Pratincola rubicola, Erithacus rubecula, Regulus cristatus, R. ignicapillus, Accentor modularis, Parus major, P. cæruleus, Troglodytes parvulus, Motacilla lugubris, M. melanope, Anthus obscurus, Ligurinus chloris, Passer domesticus, Fringilla cœlebs, Acanthis cannabina, Emberiza miliaria, E. citrinella, E. cirlus, Sturnus vulgaris, Pyrrhocorax graculus, Pica rustica, Corvus monedula, C. corax, C. corone, Alauda arvensis, Alcedo ispida, Accipiter nisus, Falco tinnunculus, Phalacrocorax carbo, P. graculus, Sula bassana, Ardea cinerea, Querquedula crecca, Columba palumbus, Charadrius pluvialis, Vanellus vulgaris, Hæmatopus ostralegus, Scolopax rusticula, Larus argentatus, L. fuscus, Rissa tridactyla, Alca torda, Colymbus arcticus, Podicipes griseigena.