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from habits.

side of the structure with lumps of earth. Certain Warblers
(Aedon and Thamnobia) for some unascertained reason in-
variably lay a piece of snake's slough in their nests--to
repel, it has been suggested, marauding lizards who may
thereby fear the neighbourhood of a deadly enemy. The
clay-built edifices of the Swallow and Martin are known
to everybody, and the Nuthatch plasters up the gaping
mouth of its nest-hole till only a postern large enough for
entrance and exit, but easy of defence, is left. In South
America we have a family of birds (Furnariida) which
construct on the branching roots of the mangrove globular |
ovens, so to speak, of mud, wherein the eggs are laid and
the young hatched. The Flamingo erects in the marshes

it frequents a mound of earth some two feet in height,
with a cavity atop, on which the hen, having oviposited,
sits astride with dangling legs, and in that remarkable atti-
tude is said to perform the duty of incubation. The
females of the Hornbills, and perhaps of the Hoopoes,
submit to incarceration during this interesting period, the
males immuring them by a barrier of mud, leaving only a
small window to admit air and food, which latter is assidu-
ously brought to the prisoners.

Occasional But though in a general way the dictates of hereditary departure instinct are rigidly observed by birds, in many species a remarkable degree of elasticity is exhibited or the rule of habit is rudely broken. Thus the noble Falcon, whose ordinary eyry is on the beetling cliff, will for the convenience of procuring prey condescend to lay its eggs on the ground in a marsh, or appropriate the nest of some other bird in a tree. The Golden Eagle, too, remarkably adapts itself to circumstances, now rearing its young on a precipitous ledge, now on the arm of an ancient monarch of the forest and again on a treeless plain, making a humble home amid grass and herbage. Herons also shew the same versatility and will breed according to circumstances in an open fen, on sea-banks or (as is most usual) on lofty trees. Such changes are easy to understand. The instinct of finding food for the family is predominant, and where most food is there will the feeders be gathered together. This explains, in all likelihood, the associated bands of Ospreys or Fish-Hawks, which in North America breed (or used to breed) in large companies where sustenance is plentiful, though in the Old World the same species brooks not the society of aught but its mate. Birds there are of eminently social predilections. In Europe, excepting Sea-fowls-whose congregations are universal and known to all-we have perhaps but the Heron, the Fieldfare, and the Rook, which habitually flock during the breeding-season; but in other parts of the world many birds unite in company at that time, and in none possibly is this habit so strongly developed as in the Anis of the Neotropical Region, the Republican Swallow of North America, and the Sociable Grosbeak of South Africa, which last joins nest to nest until the tree is said to break down under the accumulated weight of the common edifice.1

Birds

breeding in societies

Parasitic

Birds.

In the strongest contrast to these amiable qualities is the parasitic nature of the Cuckows of the Old World and the Cow-birds of the New, but this peculiarity of theirs is so well known that to dwell upon it would be needless. Enough to say that the egg of the parasite is introduced

1 There are not many works on nidification, for "Caliology" or the study of nests has hardly been deemed a distinct branch of the science. A good deal of instructive matter (not altogether free from error) will be found in Rennie's Architecture of Birds (London: 1831), and there is Mr Wallace's most interesting dissertation, "A Theory of Birds' Nests," originally published in the Journal of Travel and Natural History (1868, p. 73), and reprinted in his Contributions to the Theory of Natural Selection (London: 1870). Mr Andrew Murray's and the Duke of Argyll's remarks on this essay are contained in the same volume of the Journal named (pp. 137 and 276).

into the nest of the dupe, and after the necessary incubation by the fond fool of a foster-mother the interloper successfully counterfeits the heirs, who perish miserably, victims of his superior strength. The whole process has been often watched, but the reflective naturalist will pause to ask how such a state of things came about, and there is not much to satisfy his enquiry. Certain it is that some birds whether by mistake or stupidity do not unfrequently lay their eggs in the nests of others. It is within the knowledge of many that Pheasants' eggs and Partridges' eggs are often laid in the same nest, and it is within the knowledge of the writer that Gulls' eggs have been found in the nests of Eider-Ducks, and vice versa; that a Redstart and a Pied Flycatcher will lay their eggs in the same convenient hole -the forest being rather deficient in such accommodation; that an Owl and a Duck will resort to the same nest-box, set up by a scheming woodsman for his own advantage; and that the Starling, which constantly dispossesses the Green Woodpecker, sometimes discovers that the rightful heir of the domicile has to be brought up by the intruding tenant. In all such cases it is not possible to say which species is so constituted as to obtain the mastery, but it is not difficult to conceive that in the course of ages that which was driven from its home might thrive through the fostering of its young by the invader, and thus the abandonment of domestic habits and duties might become a direct gain to the evicted householder. This much granted, all the rest will follow easily enough, but it must be confessed that this is only a presumption, though a presumption which seems plausible if not likely.

EGGS.

This

The pains bestowed by such Birds (incomparably the most numerous of the Class), as build elaborate nests and the devices employed by those that, not doing so, display no little skill in providing for the preservation of their produce, invite some attention to the eggs which they lay. attention will perhaps be more cheerfully given when we think how many naturalists, not merely ornithologists, have been first directed to the study of the animal kingdom by the spoils they have won in their early days of birds' nesting. Birds' With some such men the fascination of this boyish pursuit nesting. has maintained its full force even in old age-a fact not so much to be wondered at when it is considered that hardly any branch of the practical study of Natural History brings the enquirer so closely in contact with many of its secrets. It is therefore eminently pardonable for the victims of this devotion to dignify their passion by the learned name of "OOLOGY," and to bespeak for it the claims of a science. Yet the present writer-once an ardent follower of the practice of birds'-nesting, and still on occasion warming to its pleasures-must confess to a certain amount of disappointment as to the benefits it was expected to confer on Systematic Ornithology, though he yields to none in his Its uses high estimate of its utility in acquainting the learner with the most interesting details of bird-life—without a knowledge of which nearly all systematic study is but work that may as well be done in a library, a museum, or a dissecting-room, and is incapable of conveying information to the learner concerning the why and the wherefore of such or such modifications and adaptations of structure. To some-and especially to those who are only anatomiststhis statement may seem preposterous, but it is in truth no such thing. What engineer can be said to understand his business if he knows not the purpose to which the machines he makes are to be applied and is unacquainted with their mode of working? We may investigate thoroughly the organs of any animal, we may trace them from the earliest moment in which they become defined, and

Discoveries f oolo

ists.

watch them as they develop to maturity, we may compre- | who early in the eighteenth century explored, chiefly for
hend the way in which every part of a complicated struc-
ture is successively built up, but if we take not the trouble
to know their effect on the economy of the creatnre we as
naturalists have done but half our task and abandon our
labour when the fulness of reward is coming upon us.
The field-naturalist, properly instructed, crowns the work
of the comparative anatomist and the physiologist, though
without the necessary education he is little more than an
empiric, even should he possess the trained cunning of the
savage on whose knowledge of the habits of wild animals
depends his chance of procuring a meal.

Perhaps the greatest scientific triumph of oologists lies in their having fully appreciated the intimate alliance of the Limicola (the great group of Snipes and Plovers) with the Gavia (the Gulls, Terns, and other birds more distantly connected with them) before it was recognized by any professed taxonomist, L'Herminier, whose researches have been much overlooked, excepted; though to such an one was given the privilege of placing that affinity beyond cavil (Huxley, Proc. Zool. Soc. 1867, pp. 426, 456-458; cf. Ibis, 1868, p. 92). In like manner it is believed that oologists first saw the need of separating from the true Passeres several groups of birds that had for many years been unhesitatingly associated with that very uniform assemblage. Diffidence as to their own capacity for meddling with matters of systematic arrangement may possibly have been the cause which deterred the men who were content to brood over birds' eggs from sooner asserting the validity of the views they held. Following the example furnished by the objects of their study, they seem to have chiefly sought to hide their offspring from the curious eye-and if such was their design it must be allowed to have been admirably successful. In enthusiastic zeal for the prosecution of their favourite researches, however, they have never yielded to, if they have not surpassed, any other class of naturalists. If a storm-swept island, only to be reached at the risk of life, held out the hope of some oological novelty there was the egg-collector (Faber, Isis, xx. pp. 633-688; Proctor, Naturalist, 1838, pp. 411, 412). Did another treasure demand his traversing a burning desert (Tristram, Ibis, 1859, p. 79) or sojourning for several winters within the wildest wastes of the Arctic Circle (Wolley, Ibis, 1859, pp. 69-76; 1861, pp. 92-106; Kennicott, Rep. Smithson. Inst. 1862, pp. 39, 40), he endured the necessary hardships to accomplish his end, and the possession to him of an empty shell of carbonate of lime,1 stained or not (as the case might be) by a secretion of the villous membrane of the parent's uterus, was to him a sufficient reward. Taxonomers, however, have probably been right in not attaching too great an importance to such systematic characters as can be deduced from the eggs of birds, but it would have been better had they not insisted so strongly as they have done on the infallibility of one or another set of characters, chosen by themselves. Oology taken alone proves to be a guide as misleading as any other arbitrary method of classification, but combined with the evidence afforded by due study of other particularities, whether superficial or deep-seated, it can scarcely fail in time to conduct us to an ornithological arrangement as nearly true to Nature as we may expect to achieve.

The first man of science who seems to have given any special thought to oology, was the celebrated Sir Thomas Browne, of Norwich, who already in 1681, when visited by John Evelyn (from whose diary we learn the fact), had assigned a place in his cabinet of rarities to a collection of birds' eggs. The next we hear of is that Count of Marsigli

1 A small proportion of carbonate of magnesia and phosphate of lime and magnesia also enters into its composition.

this kind of investigation, the valley of the Danube-a region at that time, it is almost unnecessary to remark, utterly unknown to naturalists. But there is no need to catalogue the worthies of this study. As they approach our own day their number becomes far too great to tell, and if very recently it has seemed to dwindle the reason is probably at hand in the reflection that most of the greatest prizes have been won, while those that remain to reward the aspiring appear to be just now from one cause or another almost out of reach. Perhaps at the present time the Birdsof-Paradise and their allies form the only group of any recognized distinctiveness and extent of whose eggs we know absolutely nothing-though there are important isolated forms, such as Atrichia, Heterolocha, and others, concerning the eggs as well as the breeding habits of which our ignorance is absolute, and the species of many families that have hitherto defied the zeal of oologists are very numerous. These last, however, though including some common and some not very uncommon British birds, possess in a general way comparatively little interest, since, the eggs of their nearest allies being well known, we cannot expect much to follow from the discovery of the recluses, and it is only to the impassioned collector that the obtaining of such desiderata will afford much satisfaction.

The first thing which strikes the eye of one who be- Varied holds a large collection of egg-shells is the varied hues of hues of the specimens. Hardly a shade known to the colourist is eggs. not exhibited by one or more, and some of these tints have their beauty enhanced by the glossy surface on which they are displayed, by their harmonious blending, or by the pleasing contrast of the pigments which form markings as often of the most irregular as of regular shape. But it Forms of would seem as though such markings, which a very small markings. amount of observation will shew to have been deposited on the shell a short time before its exclusion, are primarily and normally circular, for hardly any egg that bears markings at all does not exhibit some spots of that form, but that in the progress of the eggs through that part of the oviduct in which the colouring matter is laid on many of them become smeared, blotched, or protracted in some particular direction. The circular spots thus betoken the deposition of the pigment while the egg is at rest, the blurred markings show its deposition while the egg is in motion, and this motion would seem often to be at once onward and rotatory, as indicated by the spiral markings not uncommonly observable in the eggs of some Birds-of-prey and others—the larger end of the egg (when the ends differ in form) making way for the smaller.2 At the same time the eggs of a great number of birds bear, beside these last and superimposed markings, more deeply-seated stains, generally of a paler and often of an altogether different hue, and these are evidently due to some earlier dyeing process. The peculiar tint of the ground-colour, though Groundcommonly superficial, if not actually congenital with the colour. formation of the shell, would appear to be suffused soon after. The depth of colouring whether original or supervening is obviously dependent in a great measure on the constitution or bodily condition of the parent. If a bird, bearing in its oviduct a fully-formed egg, be captured, that. egg will speedily be laid under any circumstances of inconvenience to which its producer shall be subjected, but such an egg is usually deficient in coloration-fright and

2 That the larger end is protruded first was found on actual experiment by Mr Bartlett, Superintendent of the Gardens of the Zoological Society, to be the case commonly, but as an accident the position may

be sometimes reversed, and this will most likely account for the occasional deposition of markings on the sinaller instead of the larger end as not unfrequently shown in eggs of the Sparrow-hawk (Accipiter nisus). The head of the chick is always formed at the larger end.

Effect of age on

colour.

Varieties

clutch.

captivity having arrested the natural secretions. In like | Oorhodeine, Oocyan, Banded Oocyan, Yellow Ooxanthine, manner over excitement or debility of the organs, the con- Rufous Ooxanthine, a substance, giving narrow absorptionsequence of ill health, give rise to much and often very bands in the red, the true colour of which he has not yet curious abnormality. It is commonly believed that the been able to decide, and lastly Lichenoxanthine. It would older a bird is the more intensely coloured will be its eggs, be out of place here to particularize their chemical properand to some extent this belief appears to be true. Certain ties, and it is enough to say that they are closely connected Falconidae, which ordinarily lay very brilliantly-tinted eggs, either with hæmoglobin or bile-pigments, and in many and are therefore good tests, seem when young unable to respects resemble the latter more than do any other group secrete so much colouring-matter as they do when older, of colouring-matters, but do not actually agree with them. and season after season the dyes become deeper, but there The first is perhaps the most important of all the seven, is reason to think that when the bird has attained its full because it occurs more or less in the shells of so great a vigour improvement stops, and a few years later the inten- number of eggs that its entire absence is exceptional, and sity of hue begins to decline. It would be well if we had it is of a very permanent character, its general colour being more evidence, however, in support of this opinion, which of a peculiar brown-red. The second and third seem when is chiefly based on a series of eggs of one species the pure to be of a very fine blue, but the spectrum of the Golden Eagle (Aquila chrysaetus), in the writer's possession, former shows no detached bands, while that of the latter among which are some believed on good grounds to have has a well-marked detached absorbent-band near the red been the produce in the course of about twelve years of end, though the two are closely related since they yield the one and the same female. The amount of colouring-matter same product when oxidized. The fourth and fifth subsecreted and deposited seems notwithstanding to be gene- stances supply a bright yellow or reddish-yellow hue, and rally a pretty constant quantity-allowance being made for the former is particularly characteristic of eggs of the individual constitution; but it often happens-especially Emeus (Dromaus), giving rise when mixed with oocyan in the same in birds that lay only two eggs-that nearly all the dye will to the fine malachite-green which they possess, while the be deposited on one of these, leaving the other colourless; latter has only been met with in those of the Tinamous it seems, however, to be a matter of inconstancy which of (Tinamide), in which it should be mentioned that oorhothe two is first developed. Thus of two pairs of Golden deine has not been found, or perhaps in those of a CassoEagles' eggs also in the possession of the writer, one speci- wary (Casuarius), and when mixed with oocyan produces a men of each pair is nearly white while the other is deeply peculiar lead-colour. The sixth substance, as before stated, coloured, and it is known that in one case the white egg has not yet been sufficiently determined, but it would seem was laid first and in the other the coloured one. When birds in combination with others to give them an abnormally ly many mottled, and a fortiori plain, eggs, there is gene- browner tint; and the seventh appears to be identical with rilly less difference in their colouring, and though no two one which occurs in greater or less amount in almost all ein hardly ever be said to be really alike, yet the family classes of plants, but is more especially abundant in and resemblance between them all is obvious to the practised characteristic of lichens and fungi. There is a possibility It would seem however to be a peculiarity with some however of this last being in part if not wholly due to the species--and the Tree-Sparrow (Passer montanus) which growth of minute fungi, though Mr Sorby believes that lys five or six eggs may be taken as a striking example-- some such substance really is a normal constituent of the that one egg should always differ remarkably from the rest shell of eggs having a peculiar brick-red colour. That of the clutch. In addition to what has been said above gentleman is further inclined to think that oorhodeine is as to the deposition of colour in circular spots indicating in some way or other closely related to cruentine, being a pause in the progress of the egg through one part of the probably derived from the red colouring-matter of the blood oviduct, it may be observed that the cessation of motion at by some unknown process of secretion, and likewise that that time is equally shewn by the clearly defined hair-lines there is some chemical relation between the oocyans and or vermiculations seen in many eggs, and in none more the bile. commonly met with than in those of the Buntings (Emberizida). Such markings must not only have been deposited while the egg was at rest, but it must have remained motionless until the pigment was completely set, or blurred instead of sharp edges would have been the result.1

Nature of

eye.

The composition of this pigment has long excited much pigment. curiosity, and it has been commonly and rather crudely ascribed to secretions of the blood or bile;2 but very recently unexpected light has been shed upon the subject by the researches of Mr Sorby (Proc. Zool. Soc. 1875, p. 351), who, using the method of spectrum-analysis, has now ascertained the existence of seven well-marked substances in the colouring-matter of eggs, to the admixture of which in certain proportions all their tints are due. These he names

1 The principal oological works with coloured figures are the follow-
ing:-Thienemann, Fortpflanzungsgeschichte der gesammten Vögel (4to,
Leipzig: 1845); Lefèvre, Atlas des œufs des oiseaux d'Europe (8vo,
Paris: 1845); Hewitson, Coloured Illustrations of the Eggs of British
Birds (8vo, Ed. 3, London: 1856); Brewer, North American Oology (4to,
Washington: 1859); Taczanowski, Oologia Ptaków Polskich (8vo,
Warszawa: 1862); Bädeker, Die Eier der Europäischen Vögel (fol. Leip-
zig: 1863); Wolley, Ootheca Wolleyana (8vo, London: 1864)-some of
which have never been completed; but a great number of rare eggs
are also figured in various journals, as the Proceedings of the Zoologi-
cal Society, Naumannia, the Journal für Ornithologie, and The Ibis.
2 Cf. Wilke, Naumannia, 1858, pp. 393-397, and C. Leconte, Revue
et Magasin de Zoologie, 1860, pp. 199-205.

4

The grain of the egg-shell offers characters that deserve Grain of far more consideration than they have received until lately, the shell when the attention of Herr von Nathusius having been directed to the subject by some investigations carried on by Dr Landois3 and Herr Rudolf Blasius, he has brought out a series of remarkable papers in which he has arrived at the conclusion that a well-defined type of shell-structure belongs to certain families of birds, and is easily recognized under the microscope. In some cases, as in the eggs of certain Swans and Geese (Cygnus olor and C. musicus, Anser cinereus and A. segetum) even specific differences are apparent. The bearing of these researches on classification generally is of considerable importance and must be taken into account by all future taxonomers. Here we cannot enter into details, it must suffice to remark that the grain of the shell is sometimes so fine that the surface is glossy, and this is the case with a large number of Picarice, where it is also quite colourless and the contents of their eggs seen through the semi-transparent shell give an

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opalescence of great beauty; but among the Tinamous (Tinamide) colour is invariably present and their opaque eggs present the appearance of more or less globular balls of highly-burnished metal or glazed porcelain. Most birds lay eggs with a smooth shell, such as nearly all the Gavice, Limicole, and Passeres, and in some groups, as with the normal Gallina, this seems to be enamelled or much polished, but it is still very different from the brilliant surface of those just mentioned, and nothing like a definite line can be drawn between their structure and that in which the substance is dull and uniform, as among the Aleida and the Accipitres. In many of the Ratite the surface is granulated and pitted in an extraordinary manner,' and in a less degree the same feature is observable in the eggs of some other birds, as the Storks (Ciconiida). Many Water-fowls, and particularly the Ducks (Anatidae), lay eggs with a greasy or oleaginous exterior, as the collector who wishes to inscribe his specimens with marks of their identity often finds to his inconvenience; but there are other eggs, as those of the Anis (Crotophaga), the Grebes (Podicipedidae), and all of the Steganopodes, except Phaeton, which are more or less covered with a cretaceous film, often of considerable thickness and varied by calcareous protuberances.

In form eggs vary very much, and this is sometimes observable in examples not only of the same species but even from the same mother, yet a certain amount of resemblance is usually to be traced according to the natural group to which the parents belong. Those of the Owls (Strigida) and of some of the Picaria-especially those which lay the glossy eggs above spoken of-are often apparently spherical, though it is probable that if tested mathematically none would be found truly so-indeed it may be asserted that few eggs are strictly symmetrical, however nearly they may seem so, one side bulging out, though very slightly, more than the other. The really oval form, with which we are most familiar, needs no remark, but this is capable of infinite variety caused by the relative position and proportion of the major and minor axes. In nearly all the Limicole and some of the Alcide the egg attenuates very rapidly towards the smaller end, sometimes in a slightly convex curve, sometimes without perceptible curvature, and occasionally in a sensibly concave curve. The eggs having this pyriform shape are mostly those of birds which invariably lay four in a nest, and therein they lie with their points almost meeting in the centre and thus occupying as little space as possible and more easily covered by the brooding parent. Other eggs as those of the Sand-Grouse (Pterocleida) are elongated and almost cylindrical for a considerable part of their length terminating at each end obtusely, while eggs of the Grebes (Podicipedidae) which also have both ends nearly alike but pointed, are so wide in the middle as to present a biconical appearance.2

The size of eggs is generally but not at all constantly in proportion to that of the parent. The Guillemot (Alca troile) and the Raven (Corvus corax) are themselves of about equal size; their eggs vary as ten to one. The Snipe (Scolopax gallinago) and the Blackbird (Turdus merula) differ but slightly in weight, their eggs remarkably. The eggs of the Guillemot are as big as those of an Eagle; and those of the Snipe equal in size the eggs of a Partridge (Perdix cinerea). Mr Hewitson, from whom these instances

1 It is curious that Ostriches' eggs from North Africa are to be readily distinguished from those from the Cape of Good Hope by their smooth ivory-like surface, without any punctures, whereas southern specimens are rough as though pock-marked (Ibis, 1860, p.74), yet no difference that can be deemed specific has as yet been established between the birds of the north and of the south.

2 A great deal of valuable information on this and other kindred subjects is given by Des Murs, Traité général d'Oologie ornithologique (8vo, Paris: 1860).

are taken, remarks:- "The reason of this great disparity is, however, obvious; the eggs of all those birds which quit the nest soon after they are hatched, and which are consequently more fully developed at their birth, are very large." It must be added, though, that the number of eggs to be covered at one time seems also to have some relation to their size, and this offers a further explanation of the fact just mentioned with regard to the Snipe and the Partridge -the former being one of those birds which are constant in producing four, and the latter often laying as many as a dozen--for the chicks of each run as soon as they release themselves from the shell.

Incubation is performed, as is well known, by the female Incubation. of nearly all Birds, but with most of the Passeres and many others the male seems to share her tedions duties, and among the Ratito, apparently without exception, the cock takes that office wholly on himself. There are a few groups or perhaps species in which the same practice is suspected to obtain certain of the Limicolæ for instance, the Godwits (Limosa), the Phalaropes (Phalaropus), and the Dotterel (Eudromias morinellus)—and in these it is to be remarked that the hen is larger and more brightly coloured than her mate. Owing to the unfortunate neglect of those who have the opportunity of making the needful observations the period of Incubation has been ascertained in comparatively few birds, and it is here possible to deal with that subject only in the most vague and general language. It may be asserted that most of the smaller Passeres of Europe hatch their young in about thirteen days, but in a few species the term is believed to be shortened to ten or eleven days, while in the largest of that Order, the Raven, it is lengthened to some twenty-one days. This also is the period which the Barndoor-fowl ordinarily takes, but the Pheasant, though so very nearly allied, takes about twentyeight. Most Water-birds, so far as is known, and the smaller Birds-of-prey seem to require as long a time, but in the Swan incubation is protracted to six weeks. The temperature of the air is commonly credited with having something to do either in hastening or retarding exclusion from the egg, but to what extent, or even whether justly so or not, seems in the absence of precise experiments to be doubtful. be doubtful. Certain birds occasionally begin brooding as soon as the first egg is laid, and this plan unquestionably has its advantages, since the offspring being of different ages thereby become less of a burthen on the parents which have to minister to their wants, while the fostering warmth of the earlier chicks can hardly fail to aid the development of those which are unhatched, during the absence of father and mother in search of food; but most birds, and it need scarcely be said, all those the young of which run from their birth, await the completion of the clutch before sitting is begun. The care bestowed, by almost every species, on the infant-brood, is proverbial, and there is hardly any extremity of danger which one at least of the anxious parents will not incur to ward off injury from their progeny.

4

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Annual Moult.

of proper or even any food does. Important however as are its bearings on every individual of the whole Class, the subject is one which has been sadly neglected by ornithological writers and, with one exception,1 we are not aware of any connected series of observations on Moult within the whole range of their literature. The structure and mode of growth of feathers has been very well studied and described by several investigators, and must be especially treated in introducing the subject of Pterylography-or the disposition of the various plumed patches on the bird's body-which, having been found to be a most useful auxiliary in Classification, is deferred until that comes to be discussed under the article "ORNITHOLOGY." For the present we have briefly to consider the different phases which the process of Moulting offers.

As a general rule all Birds are subject to an annual Moult, and this as above stated, commonly begins immediately on the close of the breeding-season, but, as will be explained further on, there are some which undergo in addition a second or even a third partial change of plumage, and it is possible that there may be others still more exceptional, our information respecting these, however, is too meagre to make it worth while saying anything here about them. It must be acknowledged that with regard to the great majority of forms we can only judge by analogy, and though it may well be that some interesting deviations from the general rule exist of which we are altogether ignorant, yet when we consider that the Ratitæ, so far as observed, moult exactly in the same manner as other birds,2 the uniformity of the annual change may be almost taken for granted.

It is not intended here to describe the way in which a feather dies and a new one succeeds it, nor need we compare Necessity the process of moulting with the analogous shedding of the of moult. hair in Mammals or of the skin in Reptiles. Enough for our present purpose to see that such renovation is required in Birds, which nearly all have to depend upon their quills for the means of locomotion and hence of livelihood. It is easy to understand that durable as are the flight-feathers, they do not last for ever and are besides very subject to accidental breakage, the consequence of which would be the crippling of the bird. It is obviously to provide against what in most cases would be such a disaster as this last that we find the remiges, or quill-feathers of the wings, to be always shed in pairs. They drop out not indeed absolutely at the same moment, though this sometimes seems to happen, but within a few days of each other, and, equilibrium being thus preserved, the power of flight is but slightly deteriorated by their temporary loss. The same may be observed in a less degree, since there is less need of regularity, with the rest of the plumage, as a little attention to any tame bird will show, and the new feathers grow at an almost equal rate. In the young of most species the original quills are not shed during the first year, nor in the young of many does there seem to be an entire moult during that time, but in the typical Gallina, which are able to fly at a very early age, often, before they are one-third grown, the original quills, being proportioned to the duties required of them, are shed before the bird has attained its full size and are succeeded by others that serve it when it has reached maturity. In the Duck-tribe (Anatidae), however, we have a very singular exception to what has been above stated. Most of these birds shed their quillfeathers all at once, and become absolutely incapable of

1 This is a valuable paper by Herr Meves, of Stockholm (Efvers. K. Vet. Akad. Förhandl. 1854, p. 258), of which a German translation with some additions by the author may be found in Journ. für Ornith. 1855, pp. 230–238.

For the knowledge of this fact the writer is indebted to the vast experience of Mr Bartlett.

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flight for a season,3 during which time they generally seek the shelter of thick, aquatic herbage, and it is further to be particularly remarked that the males of most of two sections of the family (Anatina and Fuligulina) at the same period lose the brilliantly-coloured plumage which commonly distinguishes them and "go into eclipse," as Waterton happily said, putting on for several weeks a dingy garb much resembling that of the other sex, to resume their gay attire only when, their new quills being grown, it can be safely flaunted in the open air. Here Addition we have the first instances of Additional Moult to be men- moult. tioned. Another is not less interesting, though ornithologists must confess with shame that they have not sufficiently investigated it. This is that of the Ptarmigan (Lagopus mutus), both sexes of which not only moult after the breeding-season is over into a grey suit, and then again as autumn passes away into their snowy winter-clothing, but, divesting themselves of this last in spring, then put on each a third and most distinctive dress-these changes, however, do not extend to the quills either of the wings or tail.4

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The number of Birds which undergo a more or less entire Variatio Double Moult is very considerable, and the peculiarity is of moult not always characteristic of families or even, unless in a restricted sense, of genera. Thus while the Garden-Warbler (Sylvia salicaria) is said to moult twice in the year the Blackcap (S. atricapilla) does so but once. The same may be said of the Emberizida, in which family both practices. seem to obtain, but on the other hand the distinction in this respect between the Larks (Alaudida) and the Pipits (Anthina), belonging to the family Motacillida, appears, so far as our knowledge goes, to be invariable, though the habits and general appearance of both groups are so much alike— the Alaudide moulting but once and the Anthina, conforming to the practice of the normal Motacillida (Motacillina), twice a year-the quills, be it understood, excepted. But it would be impossible here to give more than these few examples, and indeed we scarcely know anything of the subject outside of groups belonging to the Northern hemisphere.5

In a large number of species the Additional Moult is very Partial partial, being often limited to certain portions of the plumage, moult. and it is yet an unsolved problem how far some of the changes to be observed are due to actual Moult and how far to the alteration of colour in the feathers themselves, as also the way by which this alteration of colour is produced, whether, as certainly happens in many instances, by the dropping off of the "barbicels "the fine filaments that fringe the "barbicels" which are arranged on the upper surface of each "barb" composing the web of the feather or in some other manner. With either of these last considerations we need not now concern ourselves. It is unquestionable that there are innumerable species of birds, the males at least of which put forth in spring decorative plumes unknown at any other season, and it would appear that in the majority of them the feathers which before clothed the parts whence the newly-donned ornaments grow are doffed to make room for these paraphernalia of marriage.

The subject of Additional Moult is thus intimately connected with the seasonal adornment of Birds, and as that of flight thus lost. Cf. Cunningham, Proc. Zool. Soc. 1871, p. 262. 3 One species, Micropterus cinereus, seems never to regain the power

Macgillivray (Brit. Birds, i. p. 196, London: 1837; and Nat. Hist. of Deeside, p. 405, London: 1855) thought there were four moults in this species, but that seems to be one too many. Herr Meves (loc. cit.) and the Abbé Caire (Rev. Zool. 1854, p. 494) independently made the discovery of the Triple Moult, and almost simultaneously announced it. Cf. Gloger, Journ. für Orn. 1856, p. 461.

5 The fullest list as yet published is that of Herr Meves (ut supra), but it is not entirely free from error.

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