Warm-blooded Vertebrates, which breathe by lungs, are covered with
feathers, have no teeth but a horny beak, and lay hard-shelled eggs,
which are hatched by the warmth of their body. They are adapted for
movement in the air, though not all to the same degree. The fore limbs
are modified into wings, in which, however, the parts found in Mammals
can be recognized. We distinguish in the first place a small thumb, and
then in most cases a two-jointed forefinger and a small second finger.
_Secondary quills_ (Fig. 28, BB) are attached to the ulna, and _primary
quills_ (A, 1–10) to the two metacarpals and the finger joints, while
the thumb bears the bastard wing (C). The tail feathers, or _rectrices_,
are attached to the last joint of the tail. The body is clothed with
stiff, tolerably long _contour feathers_, which conceal the soft short
_down_ from view. The bones are hollow and filled with air. Their
cavities are connected with _air-sacs_, which are found in all parts of
the body, and fill themselves with air from the lungs when the bird
begins to fly. In this way its specific gravity is reduced. The body
firm, especially the hinder part of it, which is almost immovable; the
neck, which may consist of many vertebræ (even as many as twenty-two),
can, on the contrary, be turned in many directions. Birds walk entirely
on their toes; the metatarsals are fused with one of the rows of tarsals
into a “_tarsus_” bone. Tarsus and toes are covered with horny scales.
A bird’s egg (Fig. 29) consists of a germinal disc (_h_) from which the
young bird develops, and which rests on the yolk, made up of substances
serving for the nutriment of the developing bird: the yellow (_a_) and
the white (_b_) yolk, as well as the albumen (_c_, _c_^1, “white of
egg”) in which lie two twisted cords (_chalazæ_),—finally of protective
structures: the shell-membrane (_e_) and the calcareous shell (_f_); _g_
is the air-chamber.
[Illustration:
FIG. 28.—Wing of the Buzzard.
]
[Illustration:
FIG. 29.—A Bird’s Egg.
]
When the young escape from the egg, they are either able to at once look
after themselves more or less, at least to look for their food,—in which
case they can see and are clothed with feathers at hatching (_precocious
young_; _e.g._ fowls, ducks, gulls, and pewits),—or the young remain
some time in the nest, as they are, to begin with, both blind and naked,
and in this case they are fed for some time by the parents (_nestlings_;
_e.g._ birds of prey, sparrows, nightingales, pigeons). In the frigid
and temperate zones most species of birds do not remain in their native
country after the breeding season; those which go south in the autumn
are termed _migrants_; while birds which do not migrate, but remain in
the district where they have bred, are known as _residents_ (sparrow,
jay, magpie). _Gipsy migrants_ execute more or less extensive
wanderings, influenced by want of food or other causes (woodpecker,
titmouse, golden-crested wren, tree-creeper). The travels of such birds
are not, like those of migrants, undertaken at a definite time of year,
or in definite directions (N., S.), but many of their species collect
together in large flocks for the purpose of wandering, like migrants.
The following orders are usually distinguished:
[Illustration:
FIG. 30.—The Eagle Owl (_Otus maximus_).
]
I. _Raptores_ (Birds of Prey), II. _Scansores_ (Climbers), III.
_Passeres_ (Singing Birds), IV. _Gyrantes_ (Doves), V. _Rasores_
(Scratchers), VI. _Grallatores_ (Waders), VII. _Natatores_ (Swimmers),
VIII. _Cursores_ (Running Birds).
The Order Cursores includes the ostrich-like birds, and will not here
receive further notice.
ORDER: Raptores (BIRDS OF PREY).
Upper beak hooked, covered with a skin (_cere_) at its base; four toes
possessing strong claws, and provided with pads in their under side
(Fig. 31); wings powerful. Birds of prey live in pairs, and breed once a
year in nests composed of pieces of wood and branches. The young are
nestlings (p. 51). Sight keen. These birds feed almost exclusively on
vertebrates, principally mammals and birds. An idea of their food can be
gained by examination of their “pellets”—roundish balls composed of the
indigestible parts of their food, and disgorged from twelve to twenty
hours after feeding. Two groups are distinguished—_diurnal_ and
_nocturnal_ birds of prey. The first (Figs. 31, 32) have a laterally
flattened head, eyes directed laterally, and tolerably stiff feathers.
The nocturnal forms (“owls,” Figs. 30, 33) have a large head, flattened
in front, with large eyes facing to the front, soft plumage, and
hair-like feathers on the toes, of which two are directed forwards, one
backwards, and one outwards. The radiating feathers round the eye
constitute a “veil.”
[Illustration:
FIG. 31.—Head and Foot of Falcon.
]
Predominatingly harmful (from killing domestic mammals) are the
following species occurring in Britain: the =Sea Eagle= (_Haliaëtus
albicilla_), the =Golden Eagle= (_Aquila chrysaëtus_), the =Peregrine
Falcon= (_Falco peregrinus_), the =Merlin= (_F. œsalon_), the =Hobby=
(_F. subbuteo_), the =Sparrow Hawk= (_Accipiter nisus_), the =Kite=
(_Milvus regalis_), the =Goshawk= (_Astur palumbarius_), the =Harriers=
(_Circus cyaneus_ and _C. cinerarius_), and the =Honey Buzzard= (_Pernis
apivorus_). The last effects damage by catching honey bees.
[Illustration:
FIG. 32.—The Golden Eagle (_Aquila chrysaëtus_).
]
Useful in the main, being destroyers of field-voles, are the following:
the =Kestrel= (_Falco tinnunculus_), the =Buzzard= (_Buteo vulgaris_),
the =Barn Owl= (_Strix flammea_, Fig. 33), the =Brown Owl= (_S. aluco_),
the =Little Owl= (_Athene noctua_), a casual, the =Short-eared= or
=Woodcock Owl= (_Otus brachyotus_), the =Long-eared Owl= (_O.
vulgaris_), and the =Eagle Owl= (_Otus maximus_, Fig. 30), a rare
visitor.
A bird of prey cannot simply be classed as harmful or useful; a species
mainly injurious may sometimes destroy a field vole or a destructive
bird, while a useful species may sometimes attack domestic poultry.
Game-preserving is destructive of almost all the indigenous diurnal
birds of prey, and of the owls to a less extent.
ORDER: Scansores (CLIMBERS).
Birds with two toes directed forwards and two backwards. The young are
nestlings. Here belong toucans, parrots, cuckoos, and woodpeckers. The
first two groups are limited to the tropics; woodpeckers are only of
importance in the culture of fruit trees and in forestry. I describe
briefly—
[Illustration:
FIG. 33.—The Barn Owl (_Strix flammea_).
]
The =Cuckoo= (_Cuculus canorus_, Fig. 34). Fourteen inches long, tail
eight inches. The yellowish beak is slightly curved; feet yellow. Back
blue-grey in old birds, brownish in young ones. Belly white with dark
transverse lines. Ten tail quills, flecked with white. Shy; flies like a
bird of prey. The female lays her eggs at intervals of about fourteen
days, and cannot therefore hatch them out herself. She lays the egg on
the ground, and then takes it in her bill to the nest of a small bird
which feed its young with insects (wagtail, grasshopper warbler,
nightingale, robin, lesser whitethroat, wren, lark). The cuckoo’s egg is
generally hatched by the foster parent, and the true young often do not
come out from the egg, owing to lack of warmth; or, if hatched, they are
thrown out later on by the much larger, rapidly developing young cuckoo.
Every cuckoo, therefore, is so far harmful that it costs the lives of
several insect-eating birds. But it far more than compensates for this
by destroying insects. It is especially beneficial to fruit-tree culture
and forestry, since it eats an enormous number of caterpillars; but in
late summer it comes frequently from the woodland into the fields, and
then eats the caterpillars of the cabbage white, cabbage moth, and
silver Y moth, surface caterpillars, and the larvæ of the turnip
saw-fly. It also devours mole-crickets and (naturally in the spring)
cockchafers.
[Illustration:
FIG. 34.—The Cuckoo (_Cuculus canorus_).
]
ORDER: Passeres (PERCHING BIRDS).
This order is essentially constituted by all those birds with helpless
young (p. 51), which do not belong to the two preceding orders or the
one next following. Beak without a cere. Three toes forwardly, one
backwardly directed.
Group: =Hirundinidæ= (_Swallows_).
With short flat beak, broad at the base, with gape extending far back,
and triangular as seen from above. In flight the beak is opened as
widely as possible, serving for catching insects. Wings long and
pointed. Feet short and weak, entirely unsuited or only poorly adapted
for walking; their chief use is to enable the swallow to hold fast to
different objects. Swallows fly quickly and catch insects while on the
wing. The insects on which they prey are generally unimportant to
agriculture and forestry; but they may also do good by catching crane
flies (_Tipula_), and ribbon-footed corn flies (_Chlorops_), which often
fly about our fields in enormous swarms in order to lay their eggs. All
swallows are migratory birds. There belong here—
1. True =Swallows= (_Hirundo_), with forked tails; three toes directed
to the front, one to the back. Here may be reckoned—=Swallow= (_H.
rustica_), always broods in sheltered spots, _e.g._ inside a stable,
summer-house, or verandah; =House Martin= (_H. urbica_), nests against
buildings, under the eaves for example; the =Sand Martin= (_H.
riparia_), breeds in the neighbourhood of streams, especially in
vertical banks of loamy or coherent sandy soil, where it makes its nest
at the end of a passage a yard long. The =House Martin= is shining black
on the back, white on the entire under surface and rump. The =Bank
Martin= is brownish grey on the back, white on the under side, with
brownish-grey bands on the breast.
2. =Swifts= (_Cypselus_), with forked tails and four strong, curved,
forwardly directed claws. Only one British species belongs here—the
=Swift= (_Cypselus apus_), ten inches long, brownish black except for
white throat, and with very long curved wings.
3. =Night-jars= (_Caprimulgus_), with tail not forked, soft plumage,
large head and eyes; fly at night. One species belongs here—the
=Goatsucker= (_Caprimulgus europæus_, Fig. 35), twelve inches long, grey
on the upper side, spotted with blackish brown and rusty yellow,
yellowish whitey grey with dark wavy lines on the under side. In the day
it flies awkwardly and heavily, and usually keeps under cover; by night
it flies rapidly and boldly, especially in bare spots in woods, or in
gardens and on fields. It haunts especially the neighbourhood of
sheepfolds and cattle in the meadows, since it always finds flies and
gnats there. It also catches cockchafers and various moths.
[Illustration:
FIG. 35.—The Goatsucker (_Caprimulgus europæus_).
]
Group: =Magnirostres= (_Large-beaked Perching Birds_).
Beak strong, thick, often incurved near its apex. These birds eat almost
all kinds of food, both animal and vegetable. Here belong Starlings and
Raven-like Birds (crows, magpies, jays).
The =Starling= (_Sturnus vulgaris_).
Plumage black, with a violet sheen. The tips of the contour feathers,
however, are white or bright yellowish. These white patches become so
well marked after the autumn moult, that they almost completely cover
the shining metallic black of the feathers. They gradually become
smaller; in the next spring they are almost or entirely lost. Very
serviceable. Devours, especially in autumn, many field snails, also
cockchafer grubs, wireworms, grass caterpillars, grasshoppers,
leaf-lice; also many insects destructive to fruit trees and forest
trees. The starling, however, is able to do considerable damage to
garden fruit trees, since it eats cherries, currants, and sometimes even
pears. Starlings often settle on the backs of sheep and cows in order to
pick off the vermin.
Genus: =Corvus= (_Crow-like Birds_).
Here belong—1. The =Jackdaw= (_C. monedula_), with relatively short beak
and long tarsi. Black; side of the head and neck ashen grey. Breeds in
holes in trees, chimneys, ruins, and towers. 2. The =Hooded Crow= (_G.
cornix_); bright grey, except the head, throat, wings, and tail, which
are black. Breeds in all parts of Europe east of the Elbe; occurs in
Western Europe as a gipsy migrant in winter. 3. =Carrion Crow= (_C.
corone_); black, beak stout and strongly bent at its end. Breeds in
trees, but never (like the Rook) in large numbers together. 4. =Rook=
(_C. frugilegus_); black, beak rather long; in adult specimens the head
feathers are quite worn away at the base of the beak. 5. =Raven= (_C.
corax_); much larger than the other species; black, beak very strong,
strongly curved along its entire upper side. Nowhere in large numbers.
[Illustration:
FIG. 36.—Head of Rook (_Corvus frugilegus_).
]
_Food, Benefit conferred, and Damage done._ Ravens, and sometimes even
rooks, attack lambs and sick sheep, also ducks, geese, fowls, and
pigeons. Carrion crows and hooded crows rarely attack our domestic
animals. All crows, however, steal the eggs of our poultry. They also
injure sport, since they kill hares and rabbits, young fawns, quails,
pheasants, etc. They do a little good, however, by devouring
field-voles, but, as a rule, only catch the sick ones which are not able
to move quickly. They do harm by destroying useful insect-eating birds,
also eating their eggs and young. But as insect-eaters, they are
extremely useful; they devour cockchafers, wireworms, butterflies,
surface caterpillars, crane flies and their larvæ, and field snails;
also many earthworms. As to the vegetable part of their food, they
devour, in the first place, germinating seeds; grain, peas, beans. They
also pick grain from the ear, both when ripe and, to a larger extent,
when still soft; and in doing this pull down the ear so as to crack the
stalk, thus causing more damage than by the mere eating. They also
plunder the ripening peas, and feast upon cherries, plums, apricots, and
other juicy fruits; even potatoes and turnips. All crow-like birds do
some harm and some good, only the raven (which eats scarcely any
insects) is to be always reckoned as an enemy.
The =Magpie= (_Pica caudata_) and =Jay= (_Garrulus glandarius_) are
resident birds closely related to the crows. The first affects open
tracts of land (fields, meadows, gardens) in the neighbourhood of large
trees; the latter is a woodland bird. Both birds eat almost everything:
grain, acorns, beechnuts, cherries, berries; cockchafers, wireworms, and
similar insects; the eggs and young of useful insect-eating song-birds
(such as titmice), also these little birds themselves, ducklings and
chickens, young partridges, quails, pheasants, now and then field-voles.
More harmful than useful.
Group: =Conirostres= (_Conical_-_beaked Perching Birds_).
Beak conical, thicker and shorter than in the species of the following
group. They devour insects and seeds, a few species seeds exclusively.
Here belong first the =Titmice= (_Parus_), gipsy migrants which are
extremely serviceable both in fruit-tree culture and forestry. Then the
=Larks= (especially the =Skylark=, _Alauda arvensis_, a resident), which
nest on the ground, eating insects, seeds, and in winter even leaves;
they feed their young, however, with insects. They do both good and
harm, but the former mostly preponderates. In late summer and autumn,
skylarks collect in flocks, and wander here and there for a long time:
before this, they travel south; at this time many are caught and eaten.
The male skylark sings beautifully, rising meanwhile high in the air.
The =Buntings= (_Emberiza_) have a characteristic compressed and pointed
beak; they seek their food on the ground in fields and meadows, and on
roads. The food consists of grain and insects; but since these birds
never take grains from the ear, they only do damage by picking them up
at seed-time. They feed their young with insects. The damage is usually
very inconsiderable, but, on the other hand, the benefit conferred is
slight. (=Yellow Hammer=, _E. citrinella_, a yellow-coloured resident.
The =Common Bunting=, _E. miliaria_, a grey-coloured migrant, etc.) In
the family of =Finches= a number of species are included which are of
small agricultural importance: _e.g._ the =Bullfinch= (_Pyrrhula
vulgaris_), specially attacks fruit-tree buds in March; the =Goldfinch=
(_Carduelis elegans_); the =Siskin= (_Chrysomitris spinus_); the =Lesser
Redpoll= (_Linota linaria_); the =Greenfinch= (_Ligurinus chloris_). A
few species, however, must be dealt with more fully, and, first,—
[Illustration:
FIG. 37.—Head of Bullfinch.
]
The two =Sparrows=,
_i.e._ the =House Sparrow= (_Passer domestica_) and the =Tree Sparrow=
(_P. montana_).
=House Sparrow=: ear region bright grey. A rust-coloured or yellowish
streak behind the eye. The whole throat black in the male. Wings with a
yellowish white transverse band. =Tree Sparrow=: ear region black. A
black streak behind the eye, a white band round the neck, and a black
patch on the throat. Wings with two white transverse bands. The two
sparrows are very much alike in their habits, but the house sparrow
frequents more the neighbourhood of human dwellings, even in large
towns. Both sparrows are mainly harmful; where seeds (especially those
containing starch, _e.g._ corn) are available, they prefer this kind of
food to any other; and, besides this, they chiefly bring up their young
on soft unripe grain. Sparrows devour the germinating corn after
seed-time, and also pick the grain from the ear, in which process they
at the same time do damage by breaking down the haulms so that the grain
falls out. They pick the young peas from their pods; devour, too,
several juicy tree fruits, _e.g._ cherries and grapes; and destroy young
garden seedlings, _e.g._ lettuce, spinach, garden flowers. The house
sparrow eats more insects than the tree sparrow (among them—geometer
caterpillars, injurious roller caterpillars), but leaves the most
noxious kinds untouched. Both sparrows are residents, but in autumn and
winter often collect together in large flocks.
The =Linnet= (_Linota cannabina_),
with grey-brown darkly spotted back. Belly whitish, tail black with
broad white margins. During summer the top of the head and the breast of
the male are of a beautiful red. They are often found together in flocks
during September. In spring and summer they chiefly live on
oil-containing seeds, and may even do some good by eating the seeds of
charlock; usually, however, doing much more harm by devouring the seed
of rape, flax, linseed, and hemp.
The =Chaffinch= (_Fringilla cœlebs_).
A white patch on the two outermost tail feathers and the ones next them.
Wings with one white and one yellowish transverse band. Male: upper side
of head and neck bluish grey, back brown, breast reddish brown. Female:
back grey-brown, belly whitish, breast ash-grey. The chaffinch inhabits
forests, both those of ordinary foliage trees and those consisting of
conifers; it also nests in gardens and plantations. At the beginning of
September the males separate from the females, and both sexes collect in
large flocks which haunt gardens, avenues, and bushes. In mild winters
they remain resident, but travel away if the cold is greater. The
chaffinch devours oil-containing seeds by preference, but also eats
starchy ones, and seeks its food on the ground. It does a great deal of
damage in cornfields by picking the seeds out of the soil after they
have been sown; but does not take the grain from the ear. It also eats
young seedlings. But valuable services more than counterbalance the harm
done. When the chaffinches in autumn fly about in large flocks in the
fields, they eat an enormous number of weed seeds. The young are chiefly
fed with insects, especially with caterpillars. In the spring, when the
seeds have germinated and the young corn is not yet ripe, the chaffinch
feeds itself also on insects.
Group: =Subulirostres= (_Awl-beaked Perching Birds_).
Beak slender, awl-shaped, round in transverse section. A fully developed
organ of voice. Feed almost exclusively on insects; there are only a few
species which occasionally eat seeds. A few of them, however, sometimes
devour juicy fruits (cherries, bird-cherries, elder-berries,
juniper-berries, grapes). The birds belonging to this group, without
exception, feed their young on insects. They are of service; even those
species which occasionally do damage are useful on the whole.