Page:Encyclopædia Britannica, Ninth Edition, v. 3.djvu/783

Rh MIGRATION.] BIRDS 7G5 in the North Atlantic, and thus strike the coast of Norway. 1 In that country observers may be said to be practically absent, and fowlers as a rule unknown. Such storm-beaten wanderers there consort with the allied species to be found at that season in abundance on its shores and in their com pany pursue the same southerly course. With them they cross to the east of Great Britain, and once arrived here are speedily picked out and secured by the practised gunner. But should they even escape his notice, they with their comrades follow the shore-line, where they obtain the best supply of food, until passing round the south coast they find themselves at the western extremity of England the district of the Land s End, in which, next to Norfolk and Suffolk, the greatest number of these Transatlantic stragglers have been obtained. This sugges tion may serve to shew what most likely goes on in other parts of the world, though the materials for establishing its general truth are not forthcoming. ! But returning to the subject of Migration proper, dis- tinguished as it ought to be from that of the more or less accidental occurrence of stray visitors from afar, we have here more than enough to excite our wonder, and indeed are brought face to face with perhaps the greatest mystery which the whole animal kingdom presents a mystery which attracted the attention of the earliest writers, and can in its chief point be no more explained by the modern man of science than by the simple-minded savage or the poet or prophet of antiquity. Some facts are almost universally known and have been the theme of comment in all ages and in all lands. The Hawk that stretches her wings toward the south is as familiar to the latest Nile-boat traveller or dweller on the Bosphorus as of old to the author of the book of Job. The autumnal thronging of myriads of Water fowl by the rivers of Asia is witnessed by the modern sportsman as it was of old by Homer. Anacreon welcomed the returning Swallow, in numbers which his imitators of the colder north, to whom the associations connected with it are doubly strong, have tried in vain to excel. The Indian of the Fur-Countries in forming his rude calendar names the recurring moons after the Birds-of-passage whose arrival is coincident with their changes. But there is no need to multiply instances. The flow and ebb of the mighty feathered wave has been sung by poets and reasoned of by philosophers, has given rise to proverbs and entered into popular superstitions, and yet we must say of it still that our &quot; ignorance is immense. 1 On one point and one only in connection with this subject can we boast ourselves to be clearly wiser than our ancestors. Some of them fully believed that the seasonal disappearance of the Swallow, the Nightingale, the Cuckow, and the Corncrake was due to hibernation, while others indeed doubted whether or not this was the true explana tion of the fact. It is not so long since this belief and these doubts were in vogue, but now assuredly they have no hold upon the mind of any one capable of appreciating evidence, and this absurd fancy being exploded need not again trouble us. In considering the phenomena of Migration it will be best first to take the facts, and then try to account for their cause or causes. That a very large number of Birds all over the world change their abode according to the season is well known, and we find that in almost all countries there are some species which arrive in spring, remain to breed, and depart in autumn ; others which arrive in autumn, stop for the winter, and depart in spring; and others again and these are strictly speaking the &quot; Birds of Passage &quot; which shew themselves but twice a 1 Prof. Baird s remarks on this subject are much to the point (Am. Journ. Sc., ser. 2, xli. pp. 344, 345). year, passing through the country without staying long in it, and their transient visits take place about spring and autumn. People who have given but little thought to the subject are apt to suppose that these migrants, which may thus easily be classed in three categories, are acted upon by influences of different kinds, whereas very little reflec tion will show that all are really affected by the same impulse, whatever that may be, and that the at first sight dissimilar nature of their movements is in truth almost uniform. The species which resort to this and to other tem perate countries in winter are simply those which have their breeding-quarters much nearer the poles, and in returning to them on the approach of spring are but doing exactly as do those species which, having their winter-abode nearer the equator, come to us with the spring. The Birds-of- passage proper, like our winter-visitants have their breed ing-quarters nearer the poles, but, like our summer- visitants, they seek their winter-abode nearer the equator, and thus perform a somewhat longer migration. So far there is no difficulty and no hypothesis the bringing together of these three apparently different categories is the result of simple observation. This however is not the only fact which is evident on Partial the most cursory examination. To take the birds of the uiigran British Islands as an example (though exactly similar cases are presented in other countries) we find that while there are some species, such as the Swallow or the Fieldfare, of which every individual disappears at one period of the year or another, there are other species, such as the Pied Wagtail or the Woodcock, of which only the majority of individuals vanish a few being always present 2 and these species form the so-called &quot; Partial Migrants.&quot; If we extend our view and look to birds on the continent of Europe, we find that many species are there notoriously migrant which are not generally suspected to be so in this country such as the Song-Thrush and the Redbreast, Song- both of which species closer observation has proved to be Thrusl with us subject to the migratory impulse. In respect of the former it is known that towards the end of summer or in autumn our native Song-Thrushes receive a considerable accession in numbers from the birds which arrive from the north, though the immigration is by no means so well marked as it is in Belgium, France, or Germany, where the arrival of the strangers sets all the fowlers to work, and the beginning of the Chaise aux Grives or Drosselzug is regarded in many places nearly as the Twelfth of August or the First of September is with us. In most localities in Britain the new comers depart after a short sojourn, and are accompanied by so many of the home-bred birds that in some parts of the island it may be safely declared that not a single Song-Thrush can be found from the end of November to the end of January, while in others examples can always be seen. Much the same may be said of the Redbreast. Undeniably resident as a species, Redbn attentive scrutiny will reveal the fact that its numbers are subject to very considerable variation according to the season of the year. At no time do our Redbreasts collect in bands, but towards the end of summer they may be seen in the south of England successively passing onward, the travellers being mostly if not wholly young birds of the year; and so the great majority disappear, departing it may be safely presumed for more southern countries, since a few weeks later the markets of most towns first in France and then in Italy are well supplied with this species. But the migratory influence affects, though in a less degree, many if not most of the Redbreasts that remain with us. Content during the autumn to occupy their usual haunts, - Whether these few be not migrants from another district is a pcinT, that would require further consideration.