themselves. It is certain that many genera, or even families, which are common in Burmah are wanting in the Andamans, such as the Timeliida, Pittida, Eurylamidæ, and Bucerotida, though a peculiar form of the last occurs on Narcondam, an island between the Andamans and Burmah, and there is an extreme paucity of several other families. Still the Andamans possess an avifauna of some 155 species, 17 of which (all Land-birds) are peculiar. The precise number of species found in the Nicobars is not explicitly stated by Mr Hume, but he gives 10 as peculiar to that group, which is inhabited by two very noteworthy forms-Calonas, a very remarkable genus of Columbida, widely spread throughout the Malayan archipelago, and a species of Megapodius, belonging to one of the most characteristic families of the Australian Region. The presence of these two forms would almost incline one to remove the Nicobars from the Subregion to which they have generally been assigned, and refer them rather to the Malayan Subregion.

It is now necessary to retrace our steps northward and notice China; but this is a branch of the subject on which it is as yet impossible to form an opinion. The chief authority on Chinese ornithology is unquestionably Mr Swinhoe, who has for so long a time laboured in various parts of that country equally as a public servant and a naturalist; but the results of his multitudinous contributions to our knowledge of its avifauna have never yet been tabulated, and probably their author is alone competent to perform this task without running into errors that would be disastrous in their consequences. In his latest catalogue of the Birds of China,2 he enumerates 675 species as found in that country and its islands; but valuable and carefully-drawn up as this list is, it is impossible to eliminate therefrom the species not strictly belonging to that part of the Celestial Empire which lies within our present bounds; or even were this possible, an intimate acquaintance with its ornis would be required to separate the birdsof-1 f-passage from the residents, and still more to classify them according to their several Orders and families. Add to this, that assiduously as Mr Swinhoe has himself worked in the field, and diligently as he has availed himself of such information as he could obtain from other trustworthy observers, only the outskirts of this great territory have, with few exceptions, been examined. Much is it to be hoped that he will be able in due time to bring forth the ripe fruit of his labours, but meanwhile the attempt to elucidate the peculiarities of the avifauna of China proper, that is, south at least of the Yangstzekiang and of Cochin China, would be vain if not misleading.

The two principal islands lying off the Chinese coast, however, are in a different condition. One of them has been extremely and the other tolerably well ransacked by Mr Swinhoe. In Formosa he has found 144 species, referable to 102 genera, of which 98 are found in the Himalayan Subregion, and 70 in the Malayan. The species may be thus assorted :-74 belong to wide-ranging genera, 47 to genera common to the Himalayan and Malayan Subregions, 18 are peculiar to, or characteristic of, the former Subregion, and 5 to China itself; 18 are not found in the Malayan Subregion, and no less than 34 are peculiar to the island. For Hainan Mr Swinhoe has enumerated 130 species belonging to 96 genera, of which latter 86 are common to the Malayan Subregion, and 93 to the Himalayan. Of the species 54 belong to wideranging genera, 59 to genera characteristic of the Indian

1 Of China proper Mr Elwes says little, but he includes Eastern Thibet in this Subregion. The present writer, however, is disposed to refer that, or at any rate the scene of Père David's discoveries, to the Palearctic Region.

2 Proc. Zool. Soc. 1871, pp. 337-343.

and 16 of the Palearctic Region, while 16 are believed to be peculiar to the island.

4

(2.) The Indian Subregion, still following Mr Elwes, is Indian the next to be considered. This consists of the remainder Subregion of the peninsula of India lying to the south and west of the last, as well as of the island of Ceylon. Its partition into provinces has been several times attempted, and doubtless the method proposed by Mr Blanford, when treating of the geographical distribution of Indian Reptiles, is one of the most reasonable, but even this may perhaps be premature, and here it seems preferable to abstain from doing more than consider, so far as materials are available, the avifauna of the various districts of which it is composedthe more so since the extraordinary impulse given to the study of ornithology in India by the publication of the late Dr Jerdon's work5 will doubtless in a few years place the whole subject in a very different light, for the number of Indian ornithologists is grown so considerable that that country has now a journal especially devoted to the record of their observations.

Beginning in the north-west with the Punjab, we have North-we as yet no complete list of the Birds of this most important of India. district, and we can only infer that we shall here find the Malayan influence at its least, and the Palearctic at its greatest; but descending the Indus to Sindh we have a discursive account of its ornithology by Mr Hume, from which Mr Elwes gives the following results-of 150 species observed, 41 are peculiarly desert-forms, and as such either very nearly allied to or identical with the like forms of the Palearctic and Ethiopian Regions; 40 are peculiar to the Indian Subregion, 8 are common to the Malayan, 4 to the non-desert portions of the Ethiopian, and 12 to the similar parts of the Palearctic Region, while 45 do not come under any of these heads. Omitting the desert-forms as not leading to any just conclusion, it would appear that Sindh has less affinity to the Ethiopian Region than to the Palearctic, that is to say, to its Mediterranean Subregion. The very remarkable district of Cutch yielded 115 Land-birds to Stoliczka," and these were mostly migrants or common Indian species of wide range.

Of Rajpootana and Central India we know very little, but near Goona, about 200 miles to the south of Agra, Dr King some years since observed 116 species of Landbirds; and more lately Mr Adam has noticed 171 species of Land-birds around the Sambhur Lake in its western portion.9

We must next turn eastward to Oudh, wherein Col. Oudh. Irby (Ibis, 1861, p. 217) obtained 108 species of Land-birds, but of these 23 were found only on the hills of Kumaon. There seems to be a remarkable absence of many of the most widely-spread genera of the Region, and many forms generally common to Africa are also wanting; but no doubt Mr Brooks, who has of late industriously investigated this portion of the country, will be able to supply some of these unaccountable deficiencies.

We may judge of what are politically known as the Central "Central Provinces" of India, as well as of Bundelcund, provinces Malwa, and Chota Nagpore, forming the "Gangetic" sub- of India. province of Mr Blanford, from observations made by that gentleman and Colonel M'Master, 10 wherein 190 species of Land-birds are enumerated, of which 38 have a very wide range, 57 belong to widely-ranging genera but are almost 3 Journal of the Asiatic Society of Bengal, 1870, pp. 335-376. Compare Dr Günther's remarks, Zoological Record, vii. p. 67. 5 The Birds of India. Calcutta: 1862-64.

6 Stray Feathers, i. pp. 44-49, 91-289, 419-421.

7 Journal of the Asiatic Society of Bengal, 1872, pp. 211-258.

8 Op. cit. 1868, pp. 208–218.

9 Stray Feathers, i. pp. 361-404.

10 Ibis, 1867, p. 461; Proc. As. Soc. Beng. 1869, p. 104; Jơưrn.

As. Soc. Beng. 1871, pp. 207-216.

eccan.

outhern dia.

eylon.

1

Pursuing our way southward we come to the Deccan or table-land of India, and our information respecting its ornis chiefly rests on the catalogue given by Sykes many years ago, which only contains about 150 species of Land-birds, of which about 105 belong to genera common to the Himalayan and Malayan Subregions, 27 to Himalayan but not Malayan genera, 30 to genera having Ethiopian or Palearctic affinity, and the rest to widely-ranging genera or to genera peculiar to the Indian Subregion.

The avifauna of Southern India seems to be small relatively to the extent and variety of the country, and most of its peculiar species are said to have a considerable range of latitude, though some, which are restricted to the highest hills, are only found to the southward of lat. 12° N., where several mountain-ranges reach the height of 8000 feet. No single comprehensive list of the Birds of this part of India seems lately to have been put together, and Mr Elwes gives us no statistics as the result of his investigations whereby we may compare its ornithic products with those of other districts.

Ceylon has profited by the residence of several competent naturalists-especially Mr Layard and Mr Holdsworth, and taking also its isolation into account, we are in a position to speak of this island with greater certainty than of the preceding portions of the Subregion. The latter of these gentlemen gives a list 2 numbering 323 species, of which 224 are Land-birds, and an analysis shews that, though 37 species are peculiar, only 4 belong to genera not found in Southern India, 22 belong to genera inhabiting the Himalaya but not the Malayan Subregion, and only 6 to Malayan but not Himalayan genera, while 14 are members of genera only found in India.

alayan (3.) The Malayan Subregion is the last of which we have bregion. to treat, and we have already hinted that it possibly has a connection with the Indian through the Nicobar Islands, but of course the most intimate communication between the two exists on the mainland. The birds of its conalay tinental portion, the Malay Peninsula, have never formed eninsula. the subject of a separate memoir, and to compile a complete list of them at present is a task which a more competent author has found impossible. Stoliczka has given us a catalogue of 95 species obtained in the Wellesley Province, lying opposite to Penang, and numerous species have been constantly described by various authors as coming from Malacca or Singapore, which in most cases probably means that the specimens have been purchased at one of those places. To enter into any details with respect to the Malay Peninsula, therefore, would here be impossible, but the case is different as regards the islands which form the greater part of the Subregion.

hilip

nes.

3

The Philippines, for more than a century, have supplied European ornithologists with materials of study, yet it is little more than ten years ago that any attempt to compile a complete list of their Birds was made, and that list, by Dr von Martens, was manifestly imperfect. It is only since the present article was begun that a satisfactory account of their avifauna has appeared. This is the work of Lord Walden,5 and we here avail ourselves of the results which he has so ably set forth. He enumerates 219 species, of which 150 are Land-birds; but in consequence

The

this number is really too small. Of these, 106 species are
peculiar to the archipelago-96 of them being Land-birds.
There is no species, he remarks, which is common to the
Philippines and the neighbouring island of Celebes which
does not also possess a more extended range, and there is
only one genus-Prioniturus, a very singular form of Psit-
taci-common to both and yet found nowhere else.
genera peculiar to the group are 11 in number-Pseudolalage
belonging to Campephagidae, Zeocephus to Muscicapidae,
Rhabdornis to Certhiida, Sarcops to Sturnidæ, Penelopides
to Bucerotida, Dasylophus and Lepidogrammus to Cucu-
lidæ, Pseudoptynx to Strigidæ, Phabotreron and Ptilocolpa
to Columbida, and Amaurornis to Rallida. There is also
only 1 species common to one of the Philippines-the island
of Negros-and to one other island. This is Xantholæma
rosea, which is also found in Java, and seems to be the
representative of the widely-spread X. hæmatocephala,
which ranges over India, Malacca, and Sumatra, but is not
found either in Java or Negros. It will thus be seen
that the amount of peculiarity exhibited by the avifauna
of the Philippines is very great, but it must be observed
that hardly anything is as yet known of Palawan or the
Sooloo cluster-islands which connect the Philippines with
Borneo.

Borneo is the next island to which our attention should be Borneo. directed, and this magnificent country, large enough as Mr Wallace has remarked for the whole of the United Kingdom to be set down in its midst and hidden, has lately had its avifauna carefully investigated by Dr Salvadori, the result of whose labours was published in 1874. The following may be given as a summary of them. There are 392 species, of which 325 are Land-birds, 27 belonging to the Order Accipitres, 4 to Psittaci, 99 to Picaria, 172 to Passeres, 14 to Columbæ, and 9 to Gallina. Yet there are only 3 unquestionably peculiar genera-Pityriasis, a most singular form, doubtfully referred to Laniida, Schwaneria belonging to Muscicapidae, and Heterococcyx to Cuculido. There are 58 or 59 peculiar species, all but 1 Land-birds, and at least 25, or perhaps as many as 32, which have no representatives elsewhere. Of Land-birds Borneo has, in common with Malacca and Sumatra, 226 species; in common with Java, 149; with the Philippines, 25; with the Indian Subregion, 53; with China, 72; and with Celebes, 28. A species of Megapodius (M. cumingi) is found in Borneo and also in the Philippines, and its presence in both, like that of a member of the same genus in the Nicobars already noticed, is a very remarkable fact. The comparatively little-known island of Banca, lying Banca. between Borneo and Sumatra, produces 2 peculiar species of Pittide, the one representing a species which inhabits the whole Subregion and extends to China and Siam, the other allied to two species, the first ranging from Nepal to Malacca, and the second inhabiting the Philippines, Borneo, and Sumatra.9

8

Sumatra must be considered next, or perhaps it ought Sumatra. to have been taken after Malacca, from which it is divided by so narrow a channel. The greater part of this island, its northern half especially, is unknown, and not more than 240 species can be assigned to it, of which about 20 appear to be peculiar. Its avifauna is much allied to that

6 Annali del Museo Civico di Storia Naturale di Genova, v. pp. 1-430.

7 A reputed fourth, Anais, referred to Artamide, is suspected to be founded on a manufactured specimen! Lobiophasis, since established by Mr Sharpe (Ann. and Mag. Nat. Hist. Ser. 4, xiv. p. 373), and belonging to Phasianida, probably makes another.

8 Mr Sharpe, however, considers the species distinct (Proc. Zool. Soc. 1875, p. 111).

9 But on this point compare Mr Hume's remark (Stray Feathers, ii,

p. 475).

Java.

Bali.

Uniformity and com.

We then have Java, the best-explored, the most thickly peopled, and, proportionately to its fauna, the most pecu liar, perhaps, of the Indo-Malay Islands. Here we find about 270 species of Land-birds, of which about 45 are peculiar-most of them being from the mountains in the western part of the island. The reappearance in Java of several Burmese species, as Crypsirhina varians, Picus analis, Pavo muticus, and others, which do not occur in the Malay Peninsula south of Penang, is very remark

able.

Of Bali, so interesting as the southern outpost of the Region, we only know from Mr Wallace that he saw there several Birds highly characteristic of Javan ornithology, and whether the island has any peculiar species nowhere appears. We are then brought to the brink of that remarkable strait through which runs "Wallace's Line," and erossing it find ourselves at once in the Australian Region, with which we began this protracted dissertation.

It is, of course, much to be regretted that at present our information does not allow of our treating all the Six Zoopleteness of logical Regions of the globe on a uniform plan, or of dealtreatment ing equally with their several component portions. That impossible. this will be possible in a few years, as materials are accumulated, none can doubt; but as yet we are far from the attainment of so desirable an end, and must be content to make the most of what we have. Want of space, also, has hindered the proper consideration here of many points that fully deserve notice, and especially the negative characteristics of the different Regions-often quite as important as those which are positive. Of the imperfections of the preceding sketch no one can be more painfully aware than its author, but its very imperfections may serve a useful purpose in drawing attention to the districts about which least is known. Yet it would be affectation for him not to believe that it has some actual merit, but that merit is greatly if not chiefly due to the kindness of Mr Wallace, who, in the manner already stated, has allowed his forth coming work to be laid under contribution, though in several respects its conclusions are not here adopted. That work, when published, will unquestionably form a foundation on which a noble superstructure will ultimately be erected, but it were vain to anticipate the ends which such a build-| ing will one day serve, and it would be beyond our scope to enter into any theoretical disquisition on the deductions which follow from the facts here advanced.

MIGRATION.

Most strangely and unaccountably confounded by many writers with the subject of Distribution is that of Migration. True it is that owing to the vast powers of locomotion possessed by nearly all Birds, we have individuals Migrations belonging in the main to certain groups, but by no means apparently always confined to them, straying from their proper quarirregular may yet conform to laws.

ters and occurring in places far removed, not only from the land of their birth, but from the country whither they are ordinarily bound in their journeys, to reach which is the object wherefore such journeys are undertaken. It may be that in some measure this erraticism is governed by fixed laws, and indeed indication is not wanting that such laws exist, though as yet we know much too little to lay them down with any approach to confidence. But it is obvious on reflection that granting the existence of most rigorous laws of this kind-determining the flight of every winged vagabond—they must be very different from those which are obeyed by Birds commonly called "Migratory," and migrating year after year according to a more or less

they roll. The former laws would seem to be created or controlled by purely external circumstances, which if they possess any periodicity at all possess a periodicity of cycles, and are most likely dependent in the main on cycles of the weather, but on this point observation has not yet supplied us with the means of avoiding speculation. We may indeed say almost without much risk of error that so many individuals of a foreign species-whether NorthAmerican or Asiatic-will occur in Great Britain so many times in the course of a term of years; but, though we may safely predict that if they appear at all they will do so at a certain season, it is impossible to make a forecast as to the year in which an example will turn up, or whether in one year some half-dozen may or may not occur. The matter thus becomes a matter of averages, and like all such is open to the influence of many perturbants, not that such may not well be subject to some law of which we are ignorant. Besides this, the average is hard to strike, depending as it must on the existence of favourably-placed and watchful observers. Moreover if we consider that the number of competent observers, though possibly greater in England than anywhere else in the world, has been at all times small, it is not surprising that little has been effected towards the compassing of any definite notion on this head. At present we can but attribute the appearance of foreign stragglers on our shores, and no doubt the same may be said of other countries, to the influence of storms which have driven the wanderers from their course, and though other more remote causes may possibly be assigned, there seems to be none but this on which we can safely rely. Consequently until the periodicity of storms is brought within our knowledge we must be content to abide in our ignorance of the laws which govern the appearance of the strangers. Still confining our remarks to the British Islands, the effect of these laws is in some degree constant. Singular as it may appear, the greatest number of North- AppearAmerican Birds--and especially of the Limicolæ, or Shore- ance of birds, which are recorded as having occurred in this country Birds in have been met with in the eastern part of England or Britain. Scotland. There are two ways of accounting for this fact, the first of which is the unfortunate scarcity of observing naturalists in Ireland and on its western coast especially, and this is by no means to be overlooked; but it may be remarked that in no part of the United Kingdom is the profession of the gunner more enthusiastically followed than in the sister island, and the men who pursue that vocation are all alive to the mercantile value of any strange bird which may fall in their way. Of course they have no

means of knowing what it is, yet as their spoils are sent for sale to the nearest market, it cannot but happen that if many examples of North-American species were procured by them, some proportion of these would find their way to the notice of the amateur naturalist and by him be recorded in the public prints. Now, as compared with Great Britain, this so rarely occurs in Ireland that it is by no means unfair to draw the inference that Transatlantic Birds are there far less frequently met with. The second mode of accounting for the fact above stated is that the majority of North-American Birds which occasionally visit Europe are of species which breed in somewhat high northern latitudes. On their way thence to their winterquarters, some are driven out to sea by violent westerly gales-the strongest winds, be it remembered, that prevail

1 It seems also not unlikely that the very scarcity of rare birds in Ireland is one reason why there are so few ornithologists in that

country, for here it is not uncommon for a man to have his attention bird, beetle, or butterfly, and for such a man afterwards to become

first called to zoology by meeting with some strange animal-be it beast,

no mean field-naturalist.

America

ligration roper.

Exploded

ancy of iberna

ion.

Chief facts

ion.

But returning to the subject of Migration proper, distinguished 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 Waterfowl 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 "ignorance is immense."

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 explanation 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 phænomena of Migration it will be of inigra 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 "Birds of Passage "-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).

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 reflection 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 temperate 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-ofpassage proper, like our winter-visitants have their breeding-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 migrants, 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 present2-and these species form the so-called "Partial Migrants." 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, Songboth of which species closer observation has proved to be Thrush. 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 Chasse 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, Redbreast. 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,

2 Whether these few be not migrants from another district is a point that would require further consideration.

the first sharp frost has a decided effect upon their distribution, and a heavy fall of snow drives them towards the homesteads for the larger supply of food they find there, while should severe and long-continued hard weather follow even these birds vanish, leaving only the few which have become almost domesticated.

These two species have been here chosen as illustrative cases because they are at once plentiful and familiar, and want of space only forbids us from citing others, but we shall find on inquiry that there is scarcely a Bird of either the Palearctic or Nearctic Region, whose habits are at all well known, of which much the same may not be said, and hence we are led to the conclusion that every Bird of the northern hemisphere is to a greater or less degree migratory in some part or other of its range. Such a conclusion brings us to a still more general inference-namely that Migration, instead of being the exceptional characteristic it used formerly to be thought, may really be almost universal, and though the lack of observations in other, and especially tropical, countries does not allow us to declare that such is the case, it seems very probable to be So. Before proceeding however to any further conclusions it is necessary to examine another class of facts which may possibly throw some light on the matter.

It must be within the experience of every one who has ever been a birds'-nesting boy that the most sedentary of Birds year after year occupy the same quarters in the breeding season.1 In some instances this may be ascribed, it is true, to the old haunt affording the sole or the most convenient site for the nest in the neighbourhood, but in so many instances such is not the case that we are led to believe in the existence of a real partiality, while there are quite enough exceptions to show that a choice is frequently exercised. The same may equally be said of the most migrant of Birds, and perhaps the strongest instance that has ever come to the knowledge of the writer refers to one of the latter. A pair of Stone-Curlews (Edicnemus crepitans)—a very migratory species, affecting almost exclusively the most open country-were in the habit of breeding for many years on the same spot though its character had undergone a complete change. It had been part of an extensive and barren rabbit-warren, and was become the centre of a large and flourishing plantation.

With these two sets of facts before us we may begin to try and account for the cause or causes of Migration. In some cases want of food would seem to be enough, as it is undoubtedly the most obvious cause that presents itself to our mind. The need which all animals have of finding for themselves proper and sufficient sustenance is allpowerful, and the difficulties they have to encounter in

1 Two remarkable instances of this persistency may be noticed. The nest of a Falcon (Falco peregrinus) on Avasaxa-a hill in Finland somewhat celebrated as one of the most southern points whence the midnight sun may be seen-is mentioned by the French astronomer

Maupertuis as having been observed by him in the year 1736. In 1799 it was rediscovered by Skjöldebrand and Acerbi. In 1853 Wolley found it tenanted, and from enquiries he made of the neighbours it was evident that such had yearly been the case so far as any one could remember, and so it was in 1855 as the writer can testify. In 1779 according to one account, in 1785 according to another, a pair of the Blue Titmouse (Parus cæruleus) built their nest in a large earthenware bottle placed in the branches of a tree in a garden at Oxbridge near Stockton-on-Tees. With two exceptions only, this bottle, or a second which has lately been placed close to it, has been tenanted by a pair of birds of this species from the year in which it was first occupied until 1873, when the writer saw it.-See Yarrell's British Birds, 4th ed. i. pp. 58, 486.

2 Far more so than variation of the temperature, though in popular belief that probably holds the first place. But Birds generally, as compared with other Vertebrates, are but slightly affected by extremes of heat or cold, and indeed (so far as we can judge) by most climatic influences, provided only their supply of food is not affected thereby. Cf. Max Schmidt, Zoolog. Garten, 1865, pp. 330-340.)

obtaining it are so great that none can wonder that those which possess the power of removing themselves from a place of scarcity should avail themselves of it, while it is unquestionable that no Class of animals has this facility in a greater degree than Birds. Even among many of those species which we commonly speak of as sedentary, it is only the adults which maintain their ground throughout the year. It has long been known that Birds-of-prey cus- Banishtomarily drive away their offspring from their own haunts ment of so soon as the young are able to shift for themselves. The young, reason generally, and no doubt truly, given for this behaviour, which at first sight appears so unnatural, is the impossibility of both parents and progeny getting a livelihood in the same vicinity. The practice, however, is not limited to the Birds-of-prey alone, but is much more universal. We find it to obtain with the Redbreast, and if we watch our feathered neighbours closely we shall perceive that most of them indulge in it. The period of expulsion, it is true, is in some Birds deferred from the end of summer or the autumn, in which it is usually performed, until the following spring, when indeed from the maturity of the young it must be regarded as much in the light of a voluntary secession on their part as in that of an act of parental compulsion, but the effect is ultimately the same. These cases, however, which make certainly Excepthe exception rather than the rule, we can account for in tional another manner. It is to be observed that they are confined to species having a peculiar mode of life, the individuals associating in family-parties to form small bands. The members of the Titmouse-family (Parida) offer a good instance of this peculiarity, but it requires no very abstruse reflection to perceive that the adoption of this habit is one eminently conducive to the easy attainment of their food, which is collected, as it were, into particular spots often far apart, but where it does occur occurring plentifully. plentifully. Thus a single Titmouse searching alone might hunt for a whole day without meeting with a sufficiency, while if a dozen are united by the same motive it is hardly possible for the place in which the food is lodged to escape their detection, and when discovered a few call-notes from the lucky finder are enough to assemble the whole company to share the feast. It is impossible to watch a band of any species of Titmouse, even for a few minutes, without arriving at this conclusion. One tree after another is visited by the active little rovers, and its branches examined: if nothing be forthcoming away goes the explorer to the next that presents itself, merely giving utterance to the usual twitter that serves to keep the body together. But if the object of search be found, another kind of chirp is emitted, and the next moment the several members of the band are flitting in succession to the tree and eagerly engaged with the spoil.*

cases.

food.

The mode in which the want of sustenance produces Outward Migration may best be illustrated by confining ourselves migration hemisphere. As food grows scarce towards the end of to the unquestionably migrant Birds of our own northern caused by scarcity of summer in the most northern limits of the range of a species, the individuals affected thereby seek it elsewhere. Thus doing, they press upon the haunt of other individuals: these in like manner upon that of yet others, and so on,

3 The only animals which approach Birds in the extent and character of their migrations are Fishes, of which there is no need here to say anything.

4 The case is altogether different with those species which in winter form themselves into large flocks, as most of the Finches (Fringillida) and Buntings (Emberizida). The discoverer of a favourite morsel perhaps by his actions betrays what he has obtained, and accordingly his fellows may repair to the place, but it is without invitation on his part, and the only particular bond of union not entirely selfish which keeps them together is the cry of alarm with which a stranger is greeted.