The Grouse in Health and in Disease/Chapter III/Part III
Part III. — Local Variation in the Plumage of the Grouse.
The following notes are the outcome of an attempt to find some broad differences between Grouse from the Highlands, the Lowlands, the east coast and the west coast of Scotland, and from English, Welsh, and Irish moors.
It seemed possible that, with a large series of skins of a species peculiar to the British Isles and at the same time so variable, one might discover points in the coloration of the plumage or in the size of the birds which could be attributed to the varying physical conditions under which they live.
The artificial transportation of Grouse from one county to another, generally from the southern moors to the northern, often far removed from one another, with different food and climate, has no doubt to some extent Effect of
introducing
fresh
blood. confused the issue. But this is a difficulty which will increase rather than decrease, and it is possible that the purity of the British breed (at present the only species of bird peculiar to our islands), may before long be entirely lost by the introduction of a foreign species, the Willow Grouse, on the mistaken supposition that the latter is freer from the parasite of "Grouse Disease." The foreign species has already been introduced here and there, and there has been some interbreeding with our own Red Grouse. Hence there was some reason for thinking that, unless the opportunity for collecting a series of pure bred British Red Grouse skins had been taken by the Committee, the same wide opportunity might not have occurred again before the introduction of foreign species had become popular.
The Committee's collection contains five hundred and eighty skins of the Red Grouse, including five hundred and forty adult birds of both sexes and forty chicks and pullets. These, however, cannot be taken all together in one Method of
studying
subject. series. It is essential, for purposes of comparison, that the male birds in their two plumages should be taken separately in two lots, and the females in a similar manner. Therefore the skins have to be divided as follows: —
| No. of skins. | |
| Male birds in winter plumage | 241 |
| Male birds in autumn plumage | 120 |
| Female birds in autumn plumage | 108 |
| Female birds in summer plumage | 71 |
| Immature birds of the first six months | 40 |
The largest series of skins is therefore that of the male birds in winter plumage, and it so happens that this set, both as regards sex and plumage, is best adapted by its general uniformity to give some result when arranged map-wise over a large outline of Scotland and England.
An analysis of the greater part of the collection of skins is given in the Table on p. 55.
Having thus arranged the skins into lots which are sufficiently uniform Results of
comparison. to allow of comparison, and having arranged one of these lots, the cocks in their winter plumage, for instance, according to the localities from which they were obtained, it becomes possible to make the following deductions: —
- That the general uniformity is very much more marked than might have been expected considering the character for variability which has always been attributed to the bird; the variability is lost in the mass, though it is visible in individuals.
- That, allowing for a good many exceptions, there is certainly a greater tendency to blackness in the birds of the northern Highlands than in those of the south. Or, one may say that in passing from the north of Scotland southward and westward, there is an increasing tendency to the bright red and dark red types of Grouse, which culminate in the very characteristically bright red bird of Wales and of the Midlands of England, in which the predominating colour of the feathers of the breast and under parts generally is red with fine broken black cross-lines, while these cross-lines are sometimes almost absent.
- This gradual change from north to south of black, or red and black to dark red cocks, and farther south to bright red cocks is accompanied (speaking very broadly, for there are many exceptions) by a loss of the white terminal borders which characterise the feathers of the abdomen.
| ♂ | ♀ | Totals | |||
|---|---|---|---|---|---|
| Jan. to May | Jun. to Dec. | Nov. to April | May to Oct. | ||
| Caithness | 22 | 3 | 5 | 3 | 33 |
| Sutherland | 12 | 4 | 2 | 8 | 26 |
| Roes | 6 | 16 | 3 | 4 | 29 |
| Inverness | 30 | 14 | 5 | 8 | 57 |
| Nairn | 0 | 1 | 0 | 0 | 1 |
| Moray | 11 | 0 | 1 | 0 | 12 |
| Banff | 5 | 0 | 0 | 0 | 5 |
| Aberdeen | 3 | 3 | 0 | 3 | 9 |
| Kincardine | 2 | 0 | 2 | 0 | 4 |
| Forfar | 1 | 1 | 0 | 3 | 5 |
| Perth | 17 | 16 | 5 | 13 | 51 |
| Argyll and Mull | 19+1 | 5 | 0 | 9 | 34 |
| Dumbarton | 14 | 4 | 3 | 1 | 22 |
| Stirling | 1 | 3 | 0 | 4 | 8 |
| Fife | 1 | 0 | 0 | 0 | 1 |
| Haddington | 3 | 0 | 1 | 1 | 5 |
| Midlothian | 5 | 0 | 0 | 2 | 7 |
| Lanark | 1 | 1 | 0 | 1 | 3 |
| Ayr | 1 | 2 | 2 | 5 | 10 |
| Arran | 4 | 4 | 1 | 1 | 10 |
| Peebles | 2 | 1 | 0 | 0 | 3 |
| Selkirk | 7 | 4 | 0 | 4 | 15 |
| Roxburgh | 0 | 4 | 1 | 2 | 7 |
| Dumfries | 8 | 4 | 4 | 2 | 18 |
| Kirkcudbright | 5 | 3 | 1 | 0 | 9 |
| Wigtown | 0 | 1 | 0 | 3 | 4 |
| Northumberland | 9 | 1 | 4 | 2 | 16 |
| Cumberland | 1 | 0 | 0 | 4 | 5 |
| Durham | 0 | 0 | 1 | 0 | 1 |
| Westmorland | 8 | 1 | 2 | 1 | 12 |
| Lancashire | 2 | 1 | 1 | 0 | 4 |
| Yorks | 28 | 13 | 14 | 13 | 68 |
| Derbyshire | 1 | 0 | 0 | 1 | 2 |
| Wales | 10 | 0 | 3 | 0 | 13 |
| Ireland | 0 | 0 | 0 | 1 | 1 |
| 240 | 110 | 61 | 99 | 510 | |
There is no doubt that the blacker birds of the Highlands of the north of Scotland are more frequently white spotted beneath than the birds obtained farther south. Nevertheless, the white spotting is not confined to the blacker or to the darker birds, for it may be quite a conspicuous feature in the bright red birds of Wales and England, though in the lowlands and in the north of England, especially in Yorkshire, it is a rare character, only exceptionally met with.
Mr Ogilvie-Grant, in his "Handbook to the Game Birds," 189G, says: "The ordinary varieties of the male may be divided into three distinct types of plumage: a red form, a black form, and a white-spotted form."[1]
The red form, he says, "is mostly to be found on the low grounds of Ireland, the west coast of Scotland, and the Outer Hebrides";[2] and this Red type,
cocks. statement is borne out not only by the Committee's collection of Grouse skins, but by the interesting collection made by Mr T. E. Buckley now in the Cambridge Museum. Similar birds have been obtained in some numbers from Caithness, Sutherland, the Lewes, and Inverness-shire. From Stirling, Selkirk, Northumberland, and Wicklow only one or two have been examined, but in Wales the red type is almost always met with. Welsh birds are often most typically and uniformly very bright red. Dumfriesshire also undoubtedly produces a large proportion of the same red type.
Bright red birds are not commonly characteristic of Ross-shire, Stirlingshire, or Northumberland, notwithstanding the fact that an occasional example of this type may be found in these counties. Dumbartonshire, however, and Argyllshire are said to produce more birds of a bright red type than other counties, and both these counties fall in with Sutherlandshire as forming part of the west coast of Scotland.
The following specimens have been figured to illustrate the red type of the cock Grouse: —
Pl. v. Upper surface: red type in winter plumage.
Male Grouse, No. 630. Wales, 18.3.07.
Pl. iii. Under surface: red type in winter plumage.
Male Grouse, No. 407. Glendoe, Inverness-shire, 7.12.06.
Pl. vii. Under surface: red type, changing from winter to autumn plumage.
Male Grouse, No. 915. Forfarshire, 4.6.07.
Pl. xviii. Under surface: variety of red type in autumn plumage.
Male Grouse. Loch Sween, 19.8.92. C. C. S. Parsons.
British Museum (Natural History), 92.7.13.1.
The second or black form of cock Grouse is, according to Mr Ogilvie-Grant, rarely met with, most of the black birds being mixed with the red or white-spotted forms. In the Committee's collection there are a few very Black type,
cocks. good examples of the really black type, and they come from the following areas: — Caithness, Sutherland, Perthshire, Dumbartonshire, and Yorkshire. More or less typical examples have also been obtained from Ross-shire, Aberdeenshire, Morayshire, Kincardine, Stirling, Fife, and Lancashire. At Newcastleton the low-lying grassy moors are credited with the production of the black type of Grouse, while the other types are found on the higher heather ground.
The following specimen has been figured to illustrate the black type of Grouse cock:
Pl. ii. Under surface: black type in winter plumage.
Male Grouse, No. 723. Perthshire, 4.4.07.
"The third or white -spotted form has the feathers of the breast and belly, and sometimes those of the head and upper parts, tipped with white, white. White-
spotted
type
cocks. The most typical examples of this variety are found, as a rule, on the high grounds of the north of Scotland."[3]
This statement is again confirmed by the Committee's collection, although an occasional white-spotted bird makes its appearance farther to the south. It is, however, the exception in the south, whether it be on the red or black or intermediate type. The most marked examples of this white-spotted form have come from Caithness, Sutherland, and Inverness, while Dumfries, Perthshire, and Yorkshire have each provided one or two very fair examples. In Easter Ross birds are said to be most commonly dark red or black with white beneath. At Scrafton, Middleham, the majority have white beneath, and all are dark red or bright red. The predominance of white beneath is quite conspicuous in a geographical arrangement of a large number of skins, as a character of the north of Scotland, especially throughout the Highlands.
The following specimen has been figured, illustrating the white-spotted type of cock Grouse: — Pl iv. Under surface: white-spotted form.
Male Grouse, No. 1377. Morayshire, 24.4.08.
Turning next to the female Red Grouse, no less than five distinct types are described by Mr Ogilvie-Grant: a red form, a black form, a white- spotted form, a buff-spotted form and a buff-barred form.
The difficulty in sorting hen Grouse into these classes is that a single bird may fall under three headings at once. A hen Grouse may be at once buff-spotted, white-spotted, and red or black, for the white spotting is an independent character and may occur on any type in the autumn plumage of the breast and abdomen, and this may also be definitely of the red or the black type.
In the Committee's collection, the first or red form is well represented from all parts of the country, and follows very much the same distribution as the red type of the cock Grouse.
Red examples were procured from the following areas: — Sutherland (3), Argyll (9), Arran (1), Dumbarton (1), Cumberland (l), Westmorland (1), and Red type,
hens. Wales (3), all bright red birds; Ross-shire, all dark red; Inverness-shire (3), very bright red and (3) very dark red birds; Aberdeen (3), very dark red birds; Stirling (4), red birds, with very fine black markings on the breast. Perthshire, Moray, Kincardine, Dumfriesshire, Kirkcudbright, Northumberland, Durham, and Yorkshire were all represented by red hens, generally of the dark red type.
The following specimen has been figured, illustrating the red type of hen Grouse: —
Pl. ix. Under surface: red type changing from autumn to summer plumage.
Female Grouse, No. 226. Roxburghshire, 22.5.06.
The second or black form of hen is certainly, as Mr Ogilvie-Grant says, Black type,
hens. extremely uncommon, and only one or perhaps two of the Committee's birds should be included under this heading. Two others are, however, so dark as to come with difficulty under the category of red birds.
Caithness produced a really black hen bird (No. 418), the sex of which could not possibly have been determined from its plumage. It appears to be an old hen, which has assumed male plumage. Specimen No. 338 from Inverness is almost as dark a bird, and No. 559 is a very dark reddish-black bird. No. 414 from Dumbartonshire is similarly a case in which there seems to be more black than dark red.
The following specimen has been figured to illustrate the black type of female Grouse: —
Pl. viii. Under surface: black type in autumn plumage.
Female Grouse, No. 418. Caithness, 31.12.06.
The third or white-spotted form is less rare, and, according to Mr Ogilvie-Grant, occurs as often as in the male. In the Committee's collection White-
spotted
type,
hens. it is well represented by birds from Sutherland (No. 1336); Ross-shire, a bird of the red type (No. 176); and Inverness (No. 329).
It was less to be expected that examples both of the red type and of a darker type, bordering on the black, should have been met with in Yorkshire, Lancashire, and Westmorland. Single examples were also procured in Dumfries and Kincardine. There is a fine Irish example from co. Mayo in the British Museum (Natural History), No. 99 12.1.1.
The fourth or buff-spotted form of hen Grouse, said to be "much the commonest and most usually met with, has the feathers of the upper parts spotted at the tip with whitish buff."[4] This type is generally distributed, and Buff-
spotted
type,
hens. the Committee's collection includes examples from Caithness, Sutherland, Ross, Perthshire, Ayrshire, Kincardine, Dumfries, Northumberland, Yorkshire, Westmorland, and Lancashire.
The fifth orbuff-barred form, according to Mr Ogilvie-Grant, "is met with in the south of Ireland, and resembles in winter (autumn plumage) the ordinary female in breeding plumage, having the upper parts coarsely Buff-
barred
type,
hens. barred with buff and black. Very little is known of this last barred variety, owing to the difficulty of obtaining birds except during the shooting season."[5]
The repeated endeavours of the Committee to obtain specimens resulted in one hen only being obtained from Donegal. This bird (No. 1217) was a very typical example of the buff-barred type, and it certainly differed from anything procured either in Scotland, England, or Wales.
PI. xix. Under surface: buff-barred form in autumn plumage.
Female Grouse, No. 1217. Donegal, Ireland, 17.10.07.
The nearest approach to it was to be found in four hens from Selkirkshire, and in hens from Inverness-shire, which were more accurately described as buff-barred than as buff-spotted. Single examples from Lanark, Midlothian, Roxburgh, Haddington, and Northumberland might be classed in the buff-barred type, and the females from Yorkshire were all rather of the buff-barred type, but none of these birds had quite the same markings as the Irish example. See Pl. x., female Grouse, in full summer plumage, Scottish buff-barred type.
Pl. xviii., xx., xxi., and xxii. represent abnormal varieties of the Red Grouse, and are drawn from specimens in the British Museum (Natural History). They are described in the explanation of the plates.
Two points in connection with the practical distinction of old Grouse from young, and of cock Grouse from hens, are of perennial interest both to Method of
ascertaining
sex. the gamekeeper and to the sportsman. No discussion is more apt to produce different opinions than that which arises upon the age or the sex of Grouse in certain stages of moulting, either at the luncheon-hour upon the moor or in the game-larder when the day's bag has been overhauled, and hung upon the hooks. It must be admitted that there are individual cases occurring not rarely, in which it is almost impossible to tell the sex until the bird has been cut open and the internal anatomy examined. In these doubtful cases the only way to settle the point is to cut the bird open down the middle of the abdomen, carefully turn over the whole of the intestines from the right to the left — that is,
from the bird's left side to the bird's right side — without tearing the attachments, and then, having exposed to view the flattened reddish kidneys which lie closely packed into the inequalities of the backbone and pelvis, to see whether an ovary or a testis is revealed overlying the uppermost portion of them.
In the breeding season, and in a breeding bird, there can be no doubt whatever as to the sex, for the ovary is a conspicuous bunch of more or Ovaries
and testes.
less developed ova in the hen; and in the cock the testis is a conspicuous round, white object as large as the kernel of a good-sized hazel-nut on each side of the backbone.
There is but one ovary, and it lies always on the left side of the backbone of the bird. There arc two testes, one lying on each side of the backbone, the left one generally at a slightly lower level than the right. This development of the ovary only on one, the left side, is the reason for advising the examination to be made as described above, on the left side always. One testis or the ovary cannot then be missed.
If the bird examined thus is not breeding, as may often be the case Pl. XVIII.
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male grouse, showing abnormal erythrism.
Pl. XIX.
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female grouse, buff-barred type.
Pl. XX.
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female grouse, abnormal yellow variety.
Pl. XXI.
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female grouse, grey variety.
Pl. XXII.
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female grouse, grey variety
(Type of L. persicus, G. R. Gray.)
The oviduct in a breeding hen is a large and conspicuous duct, and may, of course, contain an egg with the shell in course of formation, being pigmented in preparation for laying. The oviduct in a barren bird, or in a hen at other times than the breeding season, is a very much less conspicuous object, and is less easily found than the small and undeveloped ovary.
If no ovary is seen, but a very small blackish, or whitish, or particoloured object is found in its place which is suspected of being a testis, the intestines must then be gently separated from their attachments about the middle line of the back, and the other testis must be sought for in about the same position on the opposite side. Even in a young bird the ovary shows ova with sufficient distinctness to make doubt as to its sex an impossibility; but in a very young male bird the testes may be so small, and, being very often black, may look so unlike what is expected that both should be sought for and found before arriving at a certain conclusion as to sex.
It is easy, if the intestines are roughly handled, and the attachments torn carelessly away, to carry away the testes or the ovary from their proper position, and to remove them with the intestinal attachments. The peritoneal folds are delicate and require careful handling, and they overlie the generative organs and the kidneys; but a very little practice will enable any one to do the necessary dissection with certainty, and to arrive at an irrefutable diagnosis as to sex.
It may be said that there is no other infallible means of arriving at the sex of a Grouse at certain times of the year, for it has so often happened that experienced and careful gamekeepers, who have handled Grouse for a lifetime, have certified a specimen as a cock, when the specimen has turned out to be a hen, and vice versa. The mistake is unavoidable and excusable, for in certain individual Grouse in the autumn-winter plumage there is no reliable characteristic in the feathering or in the supraorbital comb (PI. xvi., Figs. 3 and 4), or in any external part of the bird, by which the sex can be distinguished. In most Red Grouse, even in the vast majority, the confusion of sex is not possible, for it is a matter of common knowledge that for a great part of the year the cock and the hen are so wholly unlike one another as to make it difficult for any one who did not know the birds to believe them to be of the same species. Even in the summer months when the cock puts on a plumage closely simulating the breeding plumage of the hen, there is a difference in the general tone and colour, and confusion is not likely. But in the autumn and winter it is comparatively easy to mistake the sex of some individuals, for when the hen has put on her autumn plumage for the winter, and the cock has put on his winter plumage, certain individuals of opposite sex are then indistinguishable, even to the practised eyes of the experienced gamekeeper.
Generally speaking, the feathers of the head and neck give the best indication as to sex in the autumn-winter plumage. In the male the red colouring is, as a rule, far more uniform than in the female. In the male also there is, as a rule, an absence of black markings on these red feathers, except on the upper part of the head, on the crown, and nape of the neck. The cheeks are generally a clean bronze or chestnut-red colour; so are the feathers of the chin, throat, fore-neck, and upper breast, giving the bird a very rich uniform red colour all over the head and neck. In the hen, as a rule, the whole of the feathers of these parts are crossed by narrow black bars, which five her more of the mottled and broken colouring which the cock bird only begins to assume in the early summer when he puts on the first feathers of his autumn plumage.
The feathers of the chin are a very useful indication of sex from August to November, practically throughout the shooting season, for the chestnut-red feathers which can be found on the chin of the cock Grouse in every month of the year will be sought for in vain in the hen at this time. Even in December and January they are so imperfectly red as compared with the same red feathers in the male that one may almost say that red feathers are to be found on the chin of the hen only from February to July, when they become conspicuous on account of the contrast in colour with the increasing yellowness of the breeding plumage. These red feathers persist from her previous autumn-winter plumage exactly as do the feathers of the lower breast and abdomen.
This persistence of winter-plumage feathers on the chin, lower breast, and abdomen is common to both cock and hen; but in the cock they remain, as a rule, until replaced by the following winter plumage, persisting throughout the autumn plumage change; whereas in the hen they are persistent only to June or July, and are entirely replaced during the autumn change. Even when the autumn plumage is put on, the yellow feathers of the preceding breeding plumage are almost always to some extent persistent, and they are to be found in the chin of the hen bird even though the throat and neck may be unusually red and therefore unusually like those of a cock bird.
From January to May there is no possibility, as a rule, of confusing the sexes. In June and July confusion is unlikely, but in August and onwards to December the differentiation of the sexes by the plumage is sometimes a difficult thing, and the best guide is the persistence of feathers of the preceding plumage such as occurs upon the chin in particular. We must recollect that the dominating plumage of the male is the winter plumage, while that of the female is the summer or breeding plumage.
In the autumn, especially from September and October onwards, there is the additional difficulty of distinguishing old birds and young.Distinction
between
old and
young
birds.
"Young birds in July resemble the adult female in breeding between plumage in their general colour, but the flank feathers of the adult young plumage begin to appear about this time. By the month of November the young are generally not to be distinguished from the adults." This quotation is from Mr Ogilvie-Grant.
There is one sign of age in the majority of birds in the shooting season, if it has not become obliterated — namely, the mark across the claws of recent shedding. Very often one may find the nails or claws still adhering Groove
and claw. to the toes, though ready to drop off, so that a gentle application of on claw, force removes them like small caps, leaving the new shorter claws beneath, each marked by a groove where the old claw was attached. This groove persists often for some little time, and is an infallible sign that the bird is over a year old at least. Young birds of the year do not shed their claws, and therefore never have this groove.
There is another method of determining a bird's age which is often used as a rough indication upon the moor, namely, to pull out the third primary feather of the wing at its distal end. If blood can be squeezed from the quill Wing
feathers. it is considered as a sign that the bird is of the year. If no blood can be squeezed, and the feather is old and dry, it is considered as a sign that the bird is more than a year old.
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Diagrammatic Representation of the Growth of Primaries in the Young Grouse.
This reasoning is based upon the following facts: When the chick produces its first set of primary wing feathers they are all very thin and weak, and soon become frayed out; they have rather narrow pointed ends, arc blackish-brown, in colour mottled with incomplete buff bars. Nine of these little feathers can be counted in series, and the weakest of all is the ninth counting from the distal to the proximal end. The diagrams on page 64 show very roughly the sequence of growth in the primaries of chick and pullet.
The growing power, as judged by the size of the root sheaths of these feathers, increases from the ninth distally, so that at one period of growth (F) the feather No. 4 is the longest, then a little later (G) No. 3, then still later (H) No. 2. But No. 1 remains permanently shorter than No. 2.
By the time Nos. 1 and 2 are approaching full growth, the weak chicken feathers Nos. 9, 8, 7, and so on have been shed, and in their place have appeared strong feather -roots growing strong, round-ended, uniform black primaries, instead of the weak, mottled, more narrowly pointed chicken primaries.
This shedding and replacement continues as far as No. 3 of the chicken primaries, but when No. 3 falls out Nos. 2 and 1 are found to have grown into such long and strong feathers as to fall into the series of new replacement feathers, and so they remain, now fully grown, and they can be recognised (K) by their more pointed ends having rather more of the buff markings on them than have the remainder of the primaries just grown from No. 9 to No. 3. No. 3, moreover, being the latest of the whole series of primaries to emerge, is for a time the shortest one; and, even when as long as No. 2, will be still the last one grown, and will therefore upon withdrawal produce blood at the quill end when squeezed between the finger and thumb.
This sign of blood in the quill of the third primary is not an infallible sign of youth, for it is evident that as soon as the feather finishes its growth the quill becomes as hard and dry and bloodless as all the others. The only indication will then be a slight difference in the shape and contour of the two last feathers as indicated above.
Moreover, in September it is easy to find birds obviously adult with claws attached but on the point of being shed, and having all the primaries moulted except the two most distal ones. The third then will be found to be a short feather actively growing, and if it is pulled out the growing root will be full of blood. Therefore not every bird that gives this sign is necessarily a bird of the year. The condition of the ends of the primaries, and especially of the two most distal feathers will, however, be a fair indication of age.
Another sign often used to test the age of a bird is the strength of the lower jaw. The weight of the bird is allowed to hang without support by holding the tip of the lower bill only. The bone of an old bird's jaw easily Lower
bill. stands this test, but the soft jaw of a young bird of three or four months cannot carry its weight, and the jaw either bends or breaks.
Yet another test often used is that of trying to crush in the skull with the Skull. finger and thumb; in the young bird the soft skull gives way readily, in the old bird it requires very considerable force. In judging at a moment's notice whether a young Grouse chick which rises to the dogs on the 12tth is of a shootable age and growth or not, the usual Tail
feathers. rule is probably as good a one as can be found — namely, that there should be a very clear view of black tail feathers before the young bird is fit to kill.
It is only necessary, however, to look at a few young Grouse chicks of various ages to be convinced that more than a little of the black rectrices should appear before the bird is shot. Probably most sportsmen will be guided better by the strength of the bird upon the wing than by the black tail feathers,, however clearly visible in a half-grown chick.
In dissection, the age of an old bird is apparent, perhaps as plainly upon the table as elsewhere. The fibrous tissues all toughen with age and use, and the bones become harder. The grits of the gizzard in an old bird seem to be larger and more worn into rounded pebble shapes, the reason for this has been discussed elsewhere.[6] The question, therefore, of deciding whether a bird is less than a year or more than a year old, is possible, but it seems almost impossible to judge more exactly of the age of an older bird by any sign to be discovered either externally or internally.
- ↑ "Handbook to the Game of Birds," p. 27.
- ↑ Ibid., p. 28.
- ↑ "Handbook to the Game Birds," p. 28.
- ↑ "Handbook to the Game Birds," p. 28.
- ↑ Ibid.
- ↑ Vide chap. iv. p. 95.