768 BIRDS [MIGRATION. As a rule it would seem as though Birds were not de pendent on the weather to any great degree. Occasionally the return of the Swallow or the Nightingale may be somewhat delayed, but most Sea-fowls may be trusted, it is said, as the almanack itself. Were they satellites revolving around this earth, their arrival could hardly be more surely calculated by an astronomer. Foul weather or fair, heat or cold, the Puffins (Fratercula arctica) repair to some of their stations punctually on a given day as if their move ments were regulated by clock-work. Whether they have come from far or from near we know not, but other Birds certainly come from a great distance, and yet make their appearance with scarcely less exactness. Nor is the regu larity with which certain species disappear much inferior ; every observer knows how abundant the Swift (Cypselus opus) is up to the time of its leaving its summer-home in most parts of England, the first days of August and how rarely it is seen after that time is past.
- isticsof It must be allowed, however, that, with few exceptions,
ration, the mass of statistics above spoken of has never been worked up and digested so as to allow proper inferences to be made from them, and therefore it would be premature to say that little would come of it, but the result of those few exceptions is not very encouraging. Some twenty years ago Dr von Middendorff carefully collated the records of the arrival of migratory Birds throughout the Russian Empire, but the insight into the question afforded by his published labours 1 is not very great. His chief object has been to trace what he has termed the iscpipteses (icros = cequalis, eTriTrr^crts = advolatus) or the lines of simul taneous arrival, and in the case of 7 species 2 these are laid down on the maps which accompany his treatise. The lines are found by taking the average date of arrival of each species at each place in the Russian dominions where observations have been regularly made, and connecting those places where the dates are the same for each species by lines on the map. The curves thus drawn indicate the nequality of progress made by the species in different longitudes, and assuming that the advance is directly across the isepiptesial lines, or rather the belts defined by each pair of them, the whole course of the migration is thus most accurately made known. In the case of his seven sample species the maps show their progressive advance at intervals of a few days, and the issue of the whole investigation, according to him (op. cit. p. 8) proves that in the middle of Siberia the general direction of the usual migrants is almost due north, in the east of Siberia from south-east to north-west, and in European Russia from south-west to north-east. Thus nearly all the migrants of the Russian Empire tend to converge upon the most northern part of the continent, the Taimyr Peninsula, but it is almost needless to say that few of them reach any thing like so far, since the country in those high latitudes is utterly unfit to support the majority. With the excep tion of some details, which, though possessing a certain special interest, need not here be mentioned, this treatise fails to shew more ; for the fact that there are places that notwithstanding their higher latitude are reached by Birds on their spring-migrations sooner than others in a lower latitude was already known. tes of The routes followed by migratory Birds, so far as our rants, information at present extends, has been the subject of a rally the case, by heavy falls of snow, such Birds are of course driven southward to seek their living. But as often as not the Birds arrive with the kind of weather they are commonly held to prognosticate, vhile sometimes this does not follow their appearance. 1 Die Isepiptcsen Russlands. Grundlagenzur Erforschung der Zug- i-itm und Zugrichlungen der Vogel Russlands. St Petersburg : 1855. Hi.rundo rustica, Motacillaalba, Alauda arvensis, Oriolus galbula, Cucit! us canorus, Ciconia alba, and Grus communis. very exhaustive memoir by Herr Palm en, 3 but it would be impossible within the limits of the present article to do more than mention his results concisely. He enters very fully into this part of the enquiry and lays down with much apparent probability the chief roads taken by the most migratory Birds of the Palcearctic Region in their return autumnal journey, further asserting that in the spaces be tween these lines of flight such birds do not usually occur. These main routes are, he states, nine in number. The first (A to use his notation), leaving the Siberian shores of the Polar Sea, Nova Zembla, and the North of Russia, passes down the west coast of Norway to the North Sea and the British Islands. The second (B), proceeding from Spits bergen and the adjoining islands, follows much the same course, but is prolonged past France, Spain, and Portugal to the west coast of Africa. The third (C) starts from Northern Russia, and, threading the White Sea, and the great Lakes of Onega and Ladoga, skirts the Gulf of Fin land and the southern part of the Baltic to Holstein and so to Holland, where it divides one branch uniting with the second main route (B), while the other, running up the valley of the Rhine and crossing to that of the Rhone, splits up on reaching the Mediterranean, where one path passes down the western coast of It:ily and Sicily, a second takes the line by Corsica and Sardinia, and a third follows the south coast of France and eastern coast of Spain all three paths ending in North Africa. The fourth (D), fifth (E), and sixth (F) main routes depart from the extreme north of Siberia. The fourth (D) ascending the river Ob, branches out near Tobolsk one track, diverging to tho Volga, descends that river and so passes to the Sea of Azov, the Black Sea, and thence, by the Bosphorus and yEgean, to Egypt ; another track makes for the Caspian by way of the Ural River and so leads to the Persian Gulf, while two more are lost sight of on the steppes. The fifth (E) mounts the Jennesei to Lake Baikal and so passes into Mongolia. The sixth (F) ascends the Lena and striking the Upper Amoor reaches the Sea of Japan, where it coalesces with the seventh (G) and eighth (O) which run from the eastern portion of Siberia and Kamchatka. Be sides these the ninth (X) starting from Greenland and Iceland passes by the Faeroes to the British Islands and so joining the second (B) and third (C) runs down the French coast. These being the main routes it must be added that, in Herr Palmen s opinion and that of many others, nearly all river-courses form minor routes. 4 But lay down the paths of migratory Birds, observe their coinings and goings, or strive to account for the impulse which urges them forward as we will, there still remains for consideration the most marvellous thing of all How do the birds find their way so unerringly from such im mense distances 1 This seems to be by far the most in explicable part of the matter. Year after year the migra- The re of bird their fi iner ha seemin inexpli able. 3 Om Foglarnes flyttningsviigar (Helsingfors : 1874). In this and the work of Dr von Middendorff, already cited, reference is made to almost every important publication on the subject of Migration, whi<_h renders a notice of its very extensive literature needless here, and a pretty full bibliographical list is given in Prof. Giebel s Thesaurus Ornithologies (i. pp. 146-155). Yet mention may be made of Prof. Schlegel s Over het trekkcn des Vogel s (Harlem: 1828), Mr Hodgson s " On the Migration of the Natatores and Grallatores as observed at Kath- mandu" in Asiatic Researches (xviii. pp. 122-128), and M. Marcel do Serres s Des causes des Migrations des Animaux ct particulierement des Oiseaux et des Poissons (Harlem : 1842). This last though one of the largest publications on the subject is one of the least satisfactory. Prof. Baird s excellent treatise On the Distribution and Migrations q/ North American Birds has been before adverted to. 4 In giving this abstract the present writer wishes to state that he does not thereby express his agreement with all that it contains. Herr Palmen s views deserve the fullest attention fioiu the truly scientific spirit in which they are put forward, but some of the details on which
they are founded seem to require correction.
