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IV. Decidedly Injurious Birds—i.e., those which certainly do very appreciable damage in woods and nurseries. The birds which fall under the heading of directly injurious species may be conveniently divided into four main classes—(1) Grouse, (2) Pigeons, (3) Jays, and (4) Finches.
1. Grouse (Tetraonido).—The game-birds coming under this category are all of the Grouse family (Tetraonide), and include the Capercaillie or Cock-ofthe-wood (Tetrao urogallus), not now a common bird even in the wildest parts of Scotland, the Blackcock (T. tetrix), and the Red Grouse (Lagopus scoticus).
The Capercaillie is only to be found occasionally in secluded mountainous tracts, where conifers form the ruling woodland crops. During the winter and spring it takes up its quarters in the neighbourhood of temporary nurseries or young plantations, and feeds on the buds and the foliage of the youngest shoots. As the birds keep very much to one feeding-ground circumscribed by narrow limits, the results of their destructiveness are more apparent than if they were spread over a larger area. When snow covers the ground, so that just the tips of the leading-shoots of young seedlings appear above it, they bite them off as cleanly as if they had been cut through with shears. Spruce and Silver Fir appear to offer this bird more toothsome attractions than the Scots Pine, the ordinary tree of our Highland tracts. When the advent of warmer days in spring awakens insects and worms to renewed activity, the cock-of-the-wood varies his diet to a certain extent, and feeds partially on these pests of the nurseries.
Where there are Capercaillie, conifer seed-beds can easily be protected by a light wooden framework, or by stretching wires along and across the beds, or by putting down rough branching top-ends and branches on the ground to interfere with the movement to and fro of the birds.
The Blackcock and the Common Red Grouse of Britain are both inhabitants of the heathery moors and the hill-slopes covered with heath, whortleberry, cranberry, and similar wild growth. When the supplies of food offered by these plants and by berry - bearing shrubs and trees like the Rowan or MountainAsh in autumn and early winter become exhausted, the birds are naturally forced to attack plantations or nurseries formed in the vicinity of their haunts. As they feed for the most part on the ground, their attentions are mainly confined to the needles of the lower branches, the loss of which is of no great consequence to the plant. Very often, however, they are forced to pick the buds of conifers and broad-leaved trees in order to obtain a sufficiency of food, and when thus driven by hunger they show little choice in the matter, taking Larch, Spruce, Silver Fir, Pines, Birch, Alder, Ash, Mountain - Ash, and Hazel indiscriminately, wherever they are within easy reach. They are fond of the male catkins of Birch, Alder, and Hazel in the early spring.–Moor-fowl or Ptarmigan often also damage young Scots Pine by picking out the buds of the leading-shoots.
In comparison with the damage done to plantations by hares, more especially by the blue hare (Lepus variabilis, p. 21) so common throughout the Highlands of Scotland, the injuries caused by grouse are comparatively slight, and call for no special measures of protection, which in any case it would be difficult to provide. So, too, the damage that may be done here and there to seed-beds by Pheasants is not generally very serious, although they can devour a good many acorns.
2. Pigeons (Columbide).—The Culvers or Pigeons include the Woodpigeon or Cushat (Columba palumbus), also called the Ring-dove from the dark ringlet edged with white which encircles its neck, the Wood-dove or Stock-dove (C. anas), and the Turtle dove (Turtur auritus). The two former
remain all the year in England, but the last-named is merely a summer visitor, coming in May and migrating again to warmer lands about September.
The Wood-pigeon is principally to be found in coniferous woods, where it consumes a large quantity of ripe seed, as well as buds, and the catkins of different kinds of trees at the time of flowering. Where numerous, they often do a good deal of damage by breaking the brittle leading-shoots of Douglas Fir, Silver Fir, and Spruce, by settling on them in spring and summer.—The Stock-dove takes up its quarters more frequently in mixed woods, where broad-leaved species of trees predominate, than in those stocked mainly with conifers, and it feeds to a large extent on the buds, flowers, and fruits of the former.—The Turtle dove usually takes up its abode in small patches of woodland occurring scattered here and there among fields and meadows, and feeds principally among the latter. During the spring-time all three species are wont to assemble in flocks, when they can do no small amount of damage to the sowings in fields and nurseries. And in the autumn, when the acorns and beech-nuts have ripened, the two larger kinds of pigeons love to feed off the mast, without, however, doing much damage of any really serious nature from a sylvicultural point of view.
The best preventive measure is to dip the seed in red-lead before sowing: 1 lb. of red-lead, costing about 6d., will coat at least 6 lb. of seed.
3. Jays (Corvida).- In the Common Jay (Garrulus glandarius) there is a great deal to remind one of the Magpie, and the Nutcracker (Nucifraga caryocatactes) is also mainly destructive.
The damage the Jay does to woodlands and nurseries by scratching up acorns (whence its specific name), beech-nuts, chestnuts, and similar seeds, and by.devouring the cotyledons of young seedlings, and the toll it levies on fruit of various kinds in gardens and orchards, are perhaps of less real importance than the indirect effects arising from its attacks on the eggs and young of insectivorous singing-birds. Nor is it by any means indifferent either to the attractions of the eggs and young of game-birds, or even to those of newly-born leverets. There can be little doubt that its natural tendencies of this description far outweigh any fortuitous benefits conferred by hiding acorns and other fruits that germinate later on, generally in places where they are not required, or by hunting up insects occasionally during winter and early spring, and by killing a few mice or voles now and again.—The Nut-cracker Crow adopts a very similar mode of life to our Common Jay, but shows a greater liking for coniferous seeds (which it also breaks out from the cone) than is exhibited by the latter. It is characterised by the same evil tendency towards the destruction of the eggs and young brood of birds, such as Thrushes, that are of real sylvicultural utility in keeping down the numbers of noxious insects. It is to be met with only in the wilder parts of the country, and more especially in rocky mountainous tracts, where it sometimes sows seeds by chance.
Jays can only be kept off nurseries by laying down thorny branches over the seedbeds, or using some sort of framework. Shooting them is, however, better.
4. Finches (Fringillidae).— The species of Finches that can unquestionably be classed as more beneficial in destroying insects than harmful in regard to their other habits of feeding have already been enumerated. Certain other species, however, must be regarded as committing direct damage to an extent that outweights the benefits conferred by them in helping to check the prolific tendencies of our insect enemies. To this noxious category belong the Chaffinch or Pie-finch (Fringilla coelebs), the Brambling or Mountain Finch (F. montifringilla), and the Hawfinch (Coccothraustes vulgaris); while the
Common Crossbill (Loscia curvirostra), the only species of the genus Losia that frequently visits Britain, must also be included along with them.
The damage done by the Chaffinch and the Mountain Finch is the more conspicuous owing to their habit of collecting in large flights in autumn, when they visit nurseries and areas on which sowings have been carried out, and in spring, when they feed on the cotyledons of the young seedlings. Whilst the latter pays, on the whole, most attention to the seed and seedlings of the broad-leaved species of trees, and particularly of Beech, the former exhibits a preference for conifers, among which Larch, Spruce, and Pine appear to be its favourite food.—The Hawfinch is a more varied feeder, the damage it does being more noticeable in gardens and orchards than in nurseries or woodland areas. It is difficult to keep the flocks of these small birds away from sowings to which they have once become attracted : even if frequently scared, they soon return to their feeding-ground, and by this persistency often do a considerable amount of damage to the autumn sowings. Sowings in spring are less exposed to their visitations, as at that time of the year larger and more varied supplies of food are available than is the case in late autumn and throughout the winter months.
Where Finches are very troublesome, the seed-beds may require the protection of a framework. Otherwise coating the seeds with red-lead (as above described for pigeons) is cheap and effective. Tying threads or twine across the beds, with white feathers, &c., knotted into them, is also serviceable, but scarecrows are merely of temporary use.
The voracious Crossbill feeds almost solely on tree-seeds and berries, although it sometimes devours Aphides. It is particularly partial to the seeds of conifers, although also feeding largely on the fruit of Maples, Ash, and orchard trees. After biting off the cones of Spruce or Pine, it uses its mandibles very dexterously in forcing up the bracts by first inserting the points evenly and then jerking them apart so as to displace the bracts and lay bare the seed. When this manœuvre is not quite successful, it splits open the scales of the cone from above downwards until the seed lying at the base becomes obtainable. The damage thus done is the more noticeable from the fact of this bird frequently settling down on the feedinggrounds in large flocks, and when the attentions of such flights have once been drawn to temporary nurseries, the havoc they commit may become considerable.
Arranging the above-described four classes in tabular form for convenience in overlooking them, the following are the birds of importance to the forester in Britain :
Italics.-Birds benefited by the close time prescribed in the Wild Birds' Protection Acts, 1880-1904. * Those marked with an asterisk are also of decided utility in keeping down mice and voles. | Protected under the Game Laws. Grouse have also a close time, but not Snipe or Woodcock.
It is of interest to note what has been done by legislation in the way of preserving the useful species of birds. Of the kinds that are on the whole injurious,though any damage caused is really often slight as compared with the ravages of noxious insects,—only Grouse receive any protection through a close time provided by law. But the eight months' rest provided for them is annually followed by a practical decimation during the other four months of the year. Of the rather useful species, Snipe and Woodcock also have the benefit of the protection of the game laws, without, however, any close time being prescribed, hence all they derive from that is the doubtful advantage of being shot only by certain privileged parties. But along with the other useful species printed in italics, they are specially mentioned in the Wild Birds' Protection Acts, 1880 to 1904, and thereby given protection annually from 2nd March to 31st July (both days inclusive), under a penalty of £l for each bird on each offence. For killing any other wild birds (except eighty-six specially mentioned at £1 for each offence) in the close time, the penalty is a reprimand and costs for first offence, and 5s. and costs for each bird for every subsequent offence.
Whilst we must be thankful to have any of our wild birds protected in this manner by law, the benefits have not yet been so widely conferred as they well might be ; for among the useful species there are many good friends both of the farmer and the forester against which no adequate reasons can be adduced that should debar them from obtaining protection of some sort at an early date.
Note.-In nurseries, Slugs (Limacide) and Snails (Helicidæ) are sometimes troublesome, and can best be kept down by useful birds.
Prevention and Extermination. —By far the greatest natural checks are birds, especially the Thrush, which not only eats many slugs, but is very partial to snails, breaking their shells against a stone and picking out the mollusc. Blackbirds and Starlings devour large numbers of sluga. Toads eat slugs and small snails, and moles and shrew-mice also feed on slugs. Poultry and ducks eagerly search for them. Centipedes attack slugs, and ants frequently kill snails; but only birds do any appreciable good in keeping down these molluscan pests.
The best artificial preventives are :-
2. Avoid long manure, or in fact any organic manure, where slugs are abundant in the soil ; artificial manure is preferable for a time.
3. Use dry-dressings of some irritant to kill the pests,-(a) soot and lime ; (6) salt and lime ; (c) lime and caustic soda ; or to act mechanically, (d) powdered coke. The lime must be very finely divided and quite fresh. Two or three dressings must be given, the second some 15 to 30 minutes after the first. Lime and caustic soda act best (4 parts of caustic soda to 96 of lime, well mixed). Dry-dressings, except powdered coke, should be applied very early in the morning. Heavy applications of soot are best to keep off snails, which should be dealt with mainly by hand-picking, and by trapping with cabbageleaves.
4. Heaps of bran-mash or moist oatmeal may be placed here and there as baits to attract the slugs, which may then be easily collected.
5. Rows of plants are best protected either by spreading barley-sweepings or cinders and lime along the rows, or by heavy dressings of slaked lime.
6. Hedge bottoms and rough herbage at the base of walls should be cleaned out in winter, and the masses of hibernating snails crushed.
7. Nursery-land that is thoroughly fouled with slugs should be treated with gaslime, and in the winter deeply trenched.
8. Wherever invasion is from a neighbouring wood, a deep trench should be dug and filled with lime or tar to trap the pests. Ducks and poultry in late autumn, and ducks in spring, greedily devour both kinds of pests (Board of Agriculture Leaflet No. 132— Slugs and Snails).
PROTECTION AGAINST INJURIOUS INSECTS.
Injurious Forest Insects often cause enormous damage to woodlands, though, owing to various reasons, this is not the case throughout Britain. When attacked, both young and maturing crops are damaged and often killed. Increment ceases for the time being, blanks are formed, and sometimes extensive crops are entirely destroyed. Insects that bore into the stem decrease the value of the timber greatly. The market becomes glutted with timber after any extensive destruction of woods by insects, and only reduced prices are obtainable, while perhaps no purchaser can then be found for small timber. Preventive measures and remedies may often cost a good deal; and it is sometimes necessary to let falls lie fallow for three to four years, to get rid of beetles. The extermination of swarms of insects is difficult, because they multiply enormously under favourable circumstances. Indeed, their extermination is then often next to hopeless without natural assistance in the way of epidemic fungous diseases among the larve.
Life-History of Insects.—Insects (Insecta) belong to the class of animals having jointed feet (Arthropoda). Their bodies consist of three main sections (1) head, containing organs of sense ; (2) thorax, to which the organs of locomotion are attached ; and (3) abdomen, containing organs of reproduction. They have six legs (three pairs), and generally also two pairs or one pair of wings; and they pass through various stages of development (Metamorphoses). Most insects pass through four such stages, each distinctly distinguishable from the preceding and the succeeding stages, namely—(1) Ovum or egg, (2) Larva or grub, (3) Pupa or chrysalis, and (4) Imago or mature insect. When all these separate stages are well defined, an insect is said to have a complete metamorphosis ; but in the insects forming the orders Hemiptera and Orthoptera there is merely an incomplete metamorphosis with no distinct pupal stage, because the larva gradually becomes transformed into the imago, the pseudo-pupa being then known as a nymph. The transformation of a nymph pupa into the perfect insect takes place by the already formed wings being liberated at the last moult or change of skin. The former class (comprising about 95 per cent of all insects) is called metabolic (insecta metabola) and the latter (containing only about 5 per cent) ametabolic (insecta ametabola). The Ova or eggs vary greatly in size, shape, and colour. Ovideposition sometimes takes place singly, and at others in clusters on differents parts of trees; sometimes the eggs lie naked and unprotected, and at others they are protected within the bark or else by some sort of special covering. The Larva usually hatches out in the course of a few weeks ; but in many cases it hibernates within the shell, and only emerges in the following spring. Special names are given to different kinds of larvæ. Those of most beetles are called grubs—e.g., as in the