Elementary Zoology Part 22

=The ostriches, ca.s.sowaries, etc. (Rat.i.tae).=--The ostriches, familiar to all from pictures and to some from live individuals in zoological gardens and menageries, or stuffed specimens in museums, together with a few other similar large species, are distinguished from all other birds by having the breast-bone flat instead of keeled. There are about a score of species of ostriches and ostrich-like birds all confined to the southern hemisphere. In them the wings are so reduced that flight is impossible, but the legs are long and strong, and they can run as swiftly as a galloping horse. They are said to have a stride of over twenty feet. They use their legs also as weapons, kicking viciously when angered. The true ostriches (_Struthio camelus_) (fig. 135) live in Africa. They are the largest living birds, reaching a height of nearly seven feet and weighing as much as two hundred pounds. They are hunted for their feathers, and are now kept in captivity and bred in South Africa and California for the same purpose. About five million dollars'

worth of ostrich-feathers are used each year. The eggs, which are from five to six inches long and nearly five inches thick, are laid in shallow hollows scooped out in the sand of the desert. The male undertakes most of the incubation, although when the sun is hot no brooding is necessary. The young (fig. 136) hatch in from seven to eight weeks, and can run about immediately.

[Ill.u.s.tration: FIG. 135.--Ostriches on ostrich farm at Pasadena, California. (Photograph from life.)]

The rheas, found in South America, and the ca.s.sowaries of Australia are the only other living ostrich-like birds. Their feathers are of much less value than those of the true ostrich.

[Ill.u.s.tration: FIG. 136.--Young ostriches just from egg; on ostrich farm at Pasadena, California. (Photograph from life.)]

=The loons, grebes, auks, etc. (Pygopodes).=--The loons, grebes, and auks are aquatic birds, living in both ocean and fresh waters. Their feet are webbed or lobed, and their legs set so far back that walking is very difficult and awkward. But all the birds of this order are excellent swimmers and divers. They are distinctively the diving birds.

They have short wings and almost no tail. The dab-chick or pied-billed grebe (_Podilymbus podiceps_) is common in ponds over all the country.

Its eggs are laid in a floating nest of pond vegetation and are often covered with decaying plants. The horned grebe (_Colymbus auritus_) is common west of the Mississippi in lakes and ponds. The loon or great northern diver (_Gavia imber_), found all over the United States in winter, is the largest of this group, reaching a length (from bill to tip of tail) of three feet. It is black above with many small white spots, and with a patch of white streaks on each side of the neck and on the throat; it is white on breast and belly. The female is duller, being brownish instead of black.

[Ill.u.s.tration: FIG. 137.--Murres, _Uria troile californica_, on Walrus Island, (Pribilof Group) Behring's Sea. Note the eggs scattered about over the bare rocks. (Photograph from life by the Fur Seal Commission.)]

The auks, guillemots, puffins, and murres (fig. 137) are ocean birds which gather, in the breeding season, in countless numbers on the bleak rocks and inaccessible cliffs of the northern oceans. Each female lays a single egg (in some cases two or at most three) on the bare rock or in a crevice or sort of burrow. These birds mostly fly well, but are especially at home in the water, feeding exclusively on animal substances found there. A famous species is the great auk (_Alca impennis_), which has become extinct in historical times. The last living specimen was seen in 1844.

=The gulls, terns, petrels, and albatrosses (Longipennes).=--The Longipennes are water-birds, mostly maritime, with webbed feet and very long and pointed wings. They are all strong flyers, and most of them are beautiful birds. Their prevailing colors are white, slaty or lead-blue, black, and, in the young, mottled brownish. They subsist chiefly on fish, but any animal substance will be eagerly picked up from the water; some of the gulls forage inland. Occasionally great flocks may be seen following a plow near the sh.o.r.e and feeding on the grubs and worms exposed in the freshly-turned soil. Some of the gulls, like the great black-backed gull (_Larus marinus_), attain a length of two and one-half feet. The terns (_Sterna_) are mostly smaller than the gulls, have a bill not so heavy and not hooked, and have the tail forked.

The fulmars, shearwaters, petrels, and albatrosses are strictly maritime. The albatrosses are very large, the largest being three feet long with a spread of wing of seven feet. They are often found flying easily over the open ocean at great distances from land. Like the auks and puffins, the fulmars and shearwaters gather in extraordinary numbers on rocky ocean islets or cliffs of the coast to breed.

=The cormorants, pelicans, etc. (Steganopodes).=--The Steganopodes are water-birds with full-webbed feet, and prominent gular pouch, swimmers rather than flyers like the Longipennes. The cormorants (_Phalacrocorax_) inhabit rocky coasts and are green-eyed, large, heavy, black birds with greenish-purple and violet iridescence; they are among the most familiar of seash.o.r.e birds. They feed chiefly on fish and dive and swim under water with great ability. Cormorants are rather gregarious, keeping together in small groups when fis.h.i.+ng, migrating often in great flocks, and in the breeding season gathering in immense numbers on certain rocky cliffs or islets. They build their nests of sticks and sea-weed; the eggs are three or four, and usually bluish green with white, chalky covering substance.

The pelicans are large, long-winged, short-legged water-birds with enormous bill and large gular sac which is used as a dip-net to catch fish. There are three species in North America, the white pelican (_Peleca.n.u.s erythrorhynchus_) occurring over most of the United States, the brown pelican (_P. fuscus_) of the Gulf of Mexico, and the California brown pelican (_P. californicus_) of the Pacific coast.

An interesting member of this order is the famous frigate or man-of-war bird (_Fregata aquila_), with very long wings and tail and feet extraordinarily small. The frigates have the greatest command of wing of all the birds. They cannot dive and can scarcely swim or walk.

=The ducks, geese, and swans (Anseres).=--The familiar wild ducks, of which there are forty species in North American fresh and salt waters; the geese, of which there are sixteen species, and the three species of wild swans const.i.tute the order Anseres. The bill in these birds is more or less flattened and is also lamellate, i.e. furnished along each cutting-edge with a regular series of tooth-like processes; the feet are webbed, and the body is heavy and flattened beneath. Of the fresh-water or inland ducks, the more familiar are the mallard (_Anas boschas_), a large duck with head (male) and upper neck rich glossy green; the blue-winged teal (_Querquedula discors_) and green-winged teal (_Nettion carolinense_); the shoveller (_Spatula clypeata_) with spoon-shaped bill; the beautiful crested wood-duck (_Aix sponsa_); the expert diver, the plump little ruddy duck (_Erismatura rubida_), and others. Of the coastwise ducks, the canvas-back (_Aythya vallisneria_) is famous because of its fine flavor, while among the strictly maritime ducks the eiders (_Somateria_), which live in Arctic regions, are well known for their fine down. Of the geese, the commonest is the well-known Canada goose (_Branta canadensis_), while the pure-white snow-goose (_Chen hyperborea_), with black wing-feathers and red bill, is not unfamiliar. The wild swans (_Olor_) are the largest birds of the order, and are less familiar than the ducks and geese.

=The ibises, herons, and bitterns (Herodiones).=--The tall, long-necked, long-legged, wading birds, known as herons and ibises, compose a small order, the Herodiones, of which but few representatives are at all familiar. Perhaps the most abundant species is the green heron (_Ardea virescens_) or "fly-up-the-creek," one of the smaller members of the order. The crown, back, and wings are green, the neck purplish cinnamon, and the throat and fore neck white-striped. This bird is commonly seen perching on an overhanging limb, or flying slowly up or down some small stream. The great blue heron (_Ardea herodias_) is common over the whole country. It is four feet long and grayish blue, marked with black and white. It may be seen standing alone in wet meadows or pastures, or flying heavily, with head drawn back and long legs outstretched. It breeds singly, but oftener in great heronries, in trees or bushes. Its large bulky nests contain three to six dull, greenish-blue eggs about two and one-half inches long. The white egrets of the Southern States are shot for their plumes and have been locally exterminated in some places. The night-herons (_Nycticorax_) differ from the other forms in having both the neck and legs short. The bittern (_Botaurus lentiginosus_), Indian hen, stake-driver, or thunder-pumper, as it is variously called, is a familiar member of the order, found in marshes and wet pastures, and known by its extraordinary call, sounding like the "strokes of a mallet on a stake." In color it is brownish, freckled and streaked with tawny whitish and blackish. Its nest is made on the ground; its eggs, from three to five in number, are brownish drab and about two inches long.

=The cranes, rails, and coots (Paludicolae).=--The cranes, of which three species are known in North America, are large birds with long legs and neck, part of the head being naked or with hair-like feathers. The rare whooping crane (_Grus americana_) is pure white with black on the wings, and is fifty inches long from tip of bill to tip of tail. The sand-hill crane (_G. mexicana_) is slaty gray or brownish in color, never white, and although rare in the East is quite common in the South and West. Cranes build nests on the ground, and lay but two eggs, about four inches long, brownish drab in color with large irregular spots of dull chocolate-brown.

The rails are smaller than the cranes, with short wings and very short tail. They live in marshes and swamps, and in flying let the legs hang down. Their legs are strong, and for escape they trust more to speed in running than to flight. They are hunted for food. The most abundant rail is the "Carolina crake" or "sora" (_Porzana carolina_), small and olive-brown with numerous sharp white streaks and specks. Many of these birds are shot each year during migration in the reedy swamps of the Atlantic States. The American coot or mud-hen (_Fulica americana_), dark slate-color with white bill, is one of the most familiar pond-birds over all temperate North America. Its nest consists of a ma.s.s of broken reeds resting on the water; the eggs number about a dozen, and are clay-color with pin-head dots of dark brown.

=The snipes, sandpipers, plover, etc. (Limicolae).=--The large order Limicolae, the sh.o.r.e-birds, includes the slender-legged, slender-billed, round-headed, rather small wading birds of sh.o.r.es and marshes familiar to us as snipes, plovers, sandpipers, curlews, yellow-legs, sandpeeps, turnstones, etc. Most of them are game-birds, such forms as the woodc.o.c.k and Wilson's or English snipe being much hunted. The food of these birds consists of worms and other small animals, which are chiefly obtained by probing with the rather flexible, sensitive, and usually long bill in the mud or sand. The killdeer (_aegialitis vocifera_), familiar to all in its range by its peculiar call and handsome markings, the upland or field plover (_Bartramia longicauda_), with its long legs and melodious quavering whistle, the tall, yellow-shanked "telltale" or yellow-legs (_Tota.n.u.s melanoleucus_) of the marshes and wet pastures, are among the most widespread and familiar species of the order. On the seash.o.r.e the dense flocks of white-winged, whisking sandpipers and the quickly running groups of plump ring-necked plover are familiar sights. One of the largest birds of this order is the long-billed curlew (_Numenius longirostris_) of the upland pastures. The bill of the curlew is long and curved downwards. The nests of these sh.o.r.e-birds are made on the ground and are usually little more than shallow depressions in which the few spotted eggs (four is a common number) are laid. The young are precocial.

=The grouse, quail, pheasants, turkeys, etc. (Gallinae).=--The Gallinae include most of the domestic fowls, as the hen, turkey, peac.o.c.k, guinea-fowls, and pheasants, and the grouse, quail, partridges, and wild turkeys. The chief game-birds of most countries belong to this order. They have the bill short, heavy, convex, and bony, adapted for picking up and crus.h.i.+ng seeds and grains which compose their princ.i.p.al food. Their legs are strong and usually not long, and are often feathered very low down. The Gallinae are mostly terrestrial in habit and are sometimes known as the Rasores or "scratchers." Among the more familiar wild gallinaceous birds are the quail or "Bob white"

(_Colinus virginia.n.u.s_), abundant in eastern and central United States, the ruffed grouse (_Bonasa umbellus_) of the Eastern woods, and the prairie-chicken (_Tympanuchus america.n.u.s_) of the Western prairies. The sage-hen (_Centrocercus urophasia.n.u.s_), the largest of the American grouse, reaching a length of two and one-half feet, is an interesting inhabitant of the sterile sagebrush plains of the West.

The ptarmigan (_Lagopus_) or snow-grouse, represented by several species, are found either among the rocks and snow-banks above timber line on high mountains, or in the Arctic regions. In summer their plumage is brown and white; in winter they turn pure white to harmonize with the uniform snow-covering. On the Pacific coast are several species of quail, all differing much from those of the East.

These Western species have beautiful crests of a few or several long plume-feathers, the body-plumage being also unusually beautiful. The eggs of all the Gallinae are numerous and are laid in a rude nest or simply in a depression on the ground. In many of the species polygamy is the rule. The young are precocial.

=The doves and pigeons (Columbae).=--The doves and pigeons const.i.tute a small order, the Columbae, closely related to the Gallinae. A distinguis.h.i.+ng characteristic of the Columbae lies in the bill, which is covered at the base with a soft swollen membrane or cere in which the nostrils open. The members of this order feed on fruits, seeds, and grains. Our most familiar wild species is the mourning-dove or turtle-dove (_Zenaidura macroura_) found abundantly all over the country. It lays two eggs in a loose slight nest in a low tree or on the ground. The beautiful wild or pa.s.senger pigeon (_Ectopistes migratorius_) was once extremely abundant in this country, moving about in tremendous flocks in the Eastern and Central States. But it has been so relentlessly hunted that the species is apparently becoming extinct. In the Rocky and Sierra Nevada mountains is a rather large dove, the band-tailed pigeon (_Columba fasciata_), which subsists chiefly on acorns. The domestic pigeon represented by numerous varieties, pouters, carriers, ruff-necks, fan-tails, etc., is the artificially selected descendant of the rock-dove (_Columba livia_). The young of all pigeons are altricial.

[Ill.u.s.tration: FIG. 138.--Screech-owl, _Megascops asio_. (Photograph by A. L. Princeton permission of Macmillan Co.)]

=The eagles, owls, and vultures (Raptores).=--The "birds of prey"

compose one of the larger orders, the members of which are readily recognizable. In all the bill is heavy, powerful, and strongly hooked at the tip. The feet are strong, with long, curved claws (small in the vultures) and are fitted for seizing and holding living prey, such as smaller birds, fish, reptiles, and mammals which const.i.tute the princ.i.p.al food of the true raptorial species. The vultures feed on carrion. The turkey buzzard (_Cathartes aura_) is the most familiar of the three species of carrion-feeding Raptores found in the United States. The buzzard nests on the ground or in hollow stumps or logs, and lays two white eggs (sometimes only one) blotched with brown and purplish. The largest North American vulture is the California condor (_Pseudogryphus california.n.u.s_), which attains a length of four and one-half feet, with a spread of wing of nine and one-half feet. Of the eagles, the most widespread and commonest is the bald eagle (_Haliaetus leucocephalus_). It is three feet long and when adult has the head and neck white. The golden eagle (_Aquila chrysaetos_) has the neck and head tawny brown. Of the many species of hawks, the marsh harrier (_Circus hudsonius_), abundant all over the country and readily known by its white rump, is one of the most familiar. The name "chicken-hawk" is given to two or three different species of large broad-winged hawks of the genus _Buteo_. The stout little sparrow-hawk (_Falco sparverius_), common over the whole country, is familiar and readily recognizable by its p.r.o.nounced bluish and black wings and black-and-white banded chestnut tail. Altogether fifty species of hawks and eagles are found in this country. Of the owls, the barn-owl (_Strix pratincola_) with its long triangular face and handsome mottled and spotted tawny coat is more or less familiar; the great horned owl (_Bubo virginia.n.u.s_), the snowy owl (_Nyctea nyctea_), and the great gray owl (_Scotiaptex cinerea_) are the common large species, while the red screech-owl (_Megascops asio_) (fig. 138), the most abundant owl in the country, and the strange burrowing owl (_Speotyto cunicularia_), which lives in the holes of prairie-dogs and ground-squirrels in the West, are familiar smaller ones. Thirty-two species of owls are recorded from North America.

=The parrots (Psittaci).=--The parrots, of which only one species is native in the United States, const.i.tute an interesting order of birds, the Psittaci. They are abundant in tropical America. They have a very thick strongly hooked bill, with a thick and fleshy tongue. The feet have two toes pointing forward and two backward. The plumage is usually brightly and gaudily colored. The natural voice is harsh and discordant, but many of the species can imitate with surprising cleverness the speech of man. Parrots are long-lived and usually docile, and are much kept as pets. The single native species, the Carolina paroquet (_Conurus carolinensis_), is about a foot in length, is green, with yellow head and neck and orange-red face. Its range once extended from the Gulf of Mexico north to the Great Lakes, but it has been nearly exterminated in all the States but Florida.

=The cuckoos and kingfishers (Coccyges).=--The cuckoos and kingfishers are regarded as const.i.tuting an order, Coccyges, a small group whose members are without any definite bond of union. Only ten species of North American birds belong to this order. The yellow-billed and black-billed cuckoos (_Coccyzus_) or "rain-crows" are long-tailed, slender, l.u.s.trous drab birds, which lay their eggs in the nests of others. They are notable for their peculiar rolling call. On the plains and hills of California and the southwest lives the road-runner or chaparral c.o.c.k (_Geococcyx california.n.u.s_), a strange bird belonging to the cuckoo family. It is nearly two feet long, of which length the tail makes half. These birds run so rapidly that a horse is little more than able to keep up with them. They feed on fruits, various reptiles, insects, etc. The one common kingfisher of this country, the belted kingfisher (_Ceryle alcyon_), a thick-set, heavy-billed, ashy blue-and-white bird, is familiar along streams. As it flies swiftly along it gives its rattling cry. It nests in deep holes in the stream-banks, and lays six or eight crystal-white spheroidal eggs.

=The woodp.e.c.k.e.rs (Pici).=--The familiar woodp.e.c.k.e.rs and sap-suckers compose a well-defined order, Pici, which is represented in North America by twenty-five species. The bill of the woodp.e.c.k.e.r is stout and strong, usually straight, fitted for driving or boring into wood; the tongue is long, sharp-pointed, and barbed, fitted for spearing insects. The feet have two toes turned forward and two backward; the tail-feathers are stiff and sharp-pointed and help support the bird as it clings to the vertical side of a tree-trunk or branch (fig. 139).

The food of most woodp.e.c.k.e.rs consists chiefly of insects, usually wood-boring larvae (grubs). These birds do much good by destroying many noxious insect pests of trees. A few species, the true sap-suckers, probably feed on the sap of trees. Their nests are made in holes in trees, and the eggs are pure white and rounded. The harsh and shrill cries of the woodp.e.c.k.e.rs are familiar to all.

[Ill.u.s.tration: FIG. 139.--The yellow-hammer, _Colaptes auratus_.

(Photograph by W. E. Carlin; permission of G. O. s.h.i.+elds.)]

The largest and one of the most interesting woodp.e.c.k.e.rs is the ivory-billed (_Campephilus princ.i.p.alis_), twenty inches long, glossy blue-black, with a high head-crest which is scarlet in the male. This bird lives in the heavily wooded swamps of the Southern States. Among the more abundant and widespread, and hence better known, woodp.e.c.k.e.rs are the yellow-hammers (fig. 139) or flickers (_Colaptes auratus_ in the East, _C. cafer_ in the West), the red-headed woodp.e.c.k.e.r (_Melanerpes erythrocephalus_), with its crimson head and neck and pure-white "vest"; and the black-and-white downy (_Dryobates p.u.b.escens_) and hairy (_D. villosus_) woodp.e.c.k.e.rs or "sap-suckers."

The California woodp.e.c.k.e.r (_M. formicivorus_), a near relative of the red-headed woodp.e.c.k.e.r, has the curious habit of boring small holes in the bark of oak- or pine-trees and sticking acorns into these holes.

Sometimes thousands of acorns are put into the bark of one tree, to which the birds come occasionally to break open some acorns and feed on the grubs inside.

=The whippoorwills, chimney-swifts and humming-birds (Macrochires).=--All the birds of this order are remarkable for their power of flight. They have long and pointed wings; their feet are small and weak and used only for perching or clinging. All feed on insects, which are caught on the wing by the short-beaked, wide-mouthed swifts and whippoorwills and extracted from flower-cups by the humming-birds with their long and slender bills. The whippoorwill (_Antrostomus vociferus_) is common in the woods of the East and is readily known by its call. Its two brown-blotched white eggs are laid loose on the ground or on a log or stump. The night-hawk (_Chordeiles virginia.n.u.s_), common over the whole country, is seen at twilight flying vigorously about in its search for insects. Its nesting habits are like those of the whippoorwill. The sooty-brown chimney-swifts (_Chaetura pelagica_), popularly confused with the swallows, are the common inhabitants of old chimneys, in which they build their curious saucer-shaped open-work nests. Their eggs are pure white and number four or five. Of the humming-birds but one species, the ruby-throat (_Trochilus colubris_), is to be found in the Eastern States, but in the western and especially southwestern parts of the country several other species occur. In all seventeen species have been found in the United States. The nests (fig. 140) of the hummers are very dainty little cups lined with hair or wool or plant-down. The ruby-throat lays two tiny pure-white eggs.

[Ill.u.s.tration: FIG. 140.--Nest and eggs of ruby-throat humming-bird, _Trochilus colubris_, seen from above, in apple-tree. (Photograph by E. G. Tabor; permission of Macmillan Co.)]

[Ill.u.s.tration: FIG. 141.--Horned larks, _Otocoris alpestris_, and snowflakes, _Plectrophenax nivalis_. (Photograph from life by H. W.

Menke; permission of Macmillan Co.)]

=The perchers (Pa.s.seres).=--Nearly one-half of the birds of North America belong to the great order Pa.s.seres, and of all the known birds of the world more than half are included in it. The Pa.s.seres or perching birds include the familiar song-birds and a great majority of the birds of the garden, the forest, the roadside, and the field. The feet of these birds always have four toes and are fitted for perching. The syrinx or musical apparatus is, in most, well developed. The nesting and other domestic habits are various, but the young are always hatched in a helpless condition and have to be fed and otherwise cared for by the parents for a longer or shorter time. The North American species of this order are grouped into eighteen families, as the fly-catcher family (Tyrannidae), the crow family (Corvidae), the sparrows and finches (Fringillidae), the swallows (Hirundinidae), the warblers (Mniotiltidae), the wrens (Troglodytidae), the thrushes, robins and bluebirds (t.u.r.didae), etc. In this book nothing can be said of the various species which belong to this order. However, as the pa.s.serine birds are those which most immediately surround us and which, by their familiar songs and nesting habits, most interest us, the out-door study of birds by beginning students will be devoted chiefly to the members of this order, and many species will soon be got acquainted with. The robin and bluebird will introduce us to the shyer and less familiar song-thrushes; the study of the kingbird or bee-martin will interest us in some of the other fly-catchers; from the familiar chipping sparrow and tree-sparrow we shall be led to look for their cousins the swamp-sparrows and song-sparrows, and the larger grosbeaks and cross-bills, and so on through the order.

=Determining and studying the birds of a locality.=--To identify the various species of birds in the locality of the school it will be necessary to have some book giving the descriptions of all or most of the species of the region, with tables and keys for tracing out the different forms. Such manuals or keys are numerous now; the study of birds is one of the most popular lines of nature study, and a host of bird books has been published in the last few years. The best general manual is Coues's "Key to the Birds of North America," which includes not only keys for tracing and descriptions of all the known species of birds on this continent, but also accounts of the distribution, of the nesting and eggs, and of the plumage of the young birds, besides a thorough introduction to the anatomy and physiology of birds, and directions for collecting and preserving them. Jordan's "Manual of Vertebrates" gives keys and short descriptions of the birds found east of the Missouri River; Chapman's "Handbook of the Birds of Eastern North America" is excellent. To be able to use these manuals it is necessary to have the bird's body in hand; and that means usually death for the bird. Recently there have been published several bird-keys which attempt to make it possible to determine species, the commoner ones at any rate, without such close examination. The birds in these books are usually grouped wholly artificially (without any reference to their natural relations.h.i.+ps) according to such salient characteristics as color, markings, size, habit of perching, or running, or flying, etc. These characteristics are such as can presumably be made out in the living bird by aid of an opera-gla.s.s or often with the unaided eye. Such books make no pretence to be scientific manuals nor to include any but the more usual and strongly marked species. They are usually limited to the birds of a restricted region. Such books are readily obtainable. There are several popular ill.u.s.trated "bird-magazines" devoted to accounts of the life and habits of birds. Of these "Bird-lore" is the organ of the Audubon Society for the Protection of Birds.

[Ill.u.s.tration: FIG. 142.--Western chipping sparrow, _Spizella socialis arizonae_. (Photograph from life by Eliz. and Jos. Grinnell.)]

In trying to become acquainted with the birds of a locality it must be borne in mind that the bird-fauna of any region varies with the season. Some birds live in a certain region all the year through; these are called _residents_. Some spend only the summer or breeding season in the locality, coming up from the South in spring and flying back in autumn; these are _summer residents_. Some spend only the winter in the locality, coming down from the severer North at the beginning of winter and going back with the coming of spring; these are _winter residents_. Some are to be found in the locality only in spring and autumn as they are migrating north and south between their tropical winter quarters and their northern summer or breeding home; these are _migrants_. And finally an occasional representative of certain bird species whose normal habitat does not include the given locality at all will appear now and then blown aside from its regular path of migration or otherwise astray; these are _visitants_. As to the relative importance, numerically, of these various categories among the birds which may be found in a certain region and thus form its bird-fauna we may ill.u.s.trate by reference to a definite region. Of the 351 species of birds which have been found in the State of Kansas (a region without distinct natural boundaries and fairly representative of any Mississippi valley region of similar extent), 51 are all-year residents; 125 are summer residents, 36 are winter residents, 104 are migrants, and 35 are rare visitants.

It must also be kept in mind in using bird-keys and descriptions to determine species that the descriptions and keys refer to adult birds and in ordinary plumage. Among numerous birds the young of the year, old enough to fly and as large as the adults, still differ considerably in plumage from the latter; males differ from females, and finally both males and females may change their plumage (hence color and markings) with the season. The seasonal changes of plumage accomplished by molting may be marked or hardly noticeable. "All birds get new suits at least once a year, changing in the fall. Some change in the spring also, either partially or wholly, while others have as many as three changes--perhaps, to a slight extent, a few more.... It is claimed by some that now all new colors are acquired by molt, and by others that in some instances (young hawks) an infusion or loss, as the case may be, of pigment takes place as the feather forms, and continues so long as it grows."

There is much lack and uncertainty of knowledge concerning the molting and change of plumage by birds, and careful observations by bird-students should be made on the subject.

In connection with learning the different kinds of birds in a locality, together with their names, observations should be made, and notes of them recorded, on their habits and on the relation or adaptation of structure and habit to the life of the bird. Some of the special subjects for such observation are pointed out in the following paragraphs. A suggestive book, treating of the adaptive structure and the life of birds is Baskett's "The Story of the Birds."

=Bills and feet.=--The interesting adaptation of structure to special use is admirably shown in the varying character of the bills and feet of birds. The various feeding habits and uses of the feet of different birds are readily observed, and the accompanying modification of bills and feet can be readily seen in birds either freshly killed or preserved as "bird-skins." Such skins may be made as directed on p. 467, or may be bought cheaply of taxidermists. A set of such skins, properly named, will be of great help in studying birds, and should be in the high-school collection. In some cases the general structure of feet and bills may be seen in the live birds by the use of an opera-gla.s.s. The characters of bills and feet are much used in the cla.s.sification of birds, so that any knowledge of them gained primarily in the study of adaptations will have a secondary use in cla.s.sification work.

[Ill.u.s.tration: FIG. 143.--Russet-backed thrush, _t.u.r.dus ustulatus_.

(Photograph from life by Eliz. and Jos. Grinnell.)]

Note the foot of the robin, bluebird, catbird, wrens, warblers and other pa.s.serine or perching birds. It has three unwebbed toes in front, and a long hind toe perfectly opposable to the middle front one. This is the _perching_ foot. Note the so-called _zyG.o.dactyl_ foot of the woodp.e.c.k.e.r, with two toes projecting in front and partly yoked together, and two similarly yoked projecting behind. Note the webbed swimming foot of the aquatic birds; note the different degrees of webbing, from the _totipalmate_, where all four toes are completely webbed, _palmate_, where the three front toes only are bound together but the web runs out to the claws, to the _semi-palmate_, where the web runs out only about half way. Note the _lobate_ foot of the coots and phalaropes. Note the long slender wading legs of the sandpipers, snipe and other sh.o.r.e birds; the short heavy strong leg of the divers; the small weak leg of the swifts and humming-birds, almost always on the wing; the stout heavily nailed foot of the scratchers, as the hens, grouse, and turkeys; and the strong grasping talons, with their sharp long curving nails, of the hawks and owls and other birds of prey. In all these cases the fitness of the structure of the foot to the special habits of the bird is apparent.

Similarly the shape and structural character of the bill should be noted, as related to its use, this being chiefly concerned of course with the feeding habits. Note the strong hooked and dentate bill of the birds of prey; they tear their prey. Note the long slender sensitive bill of the sandpipers; they probe the wet sand for worms.

Note the short weak bill and wide mouth of the night-hawk and whippoorwill and of the swifts and swallows; they catch insects in this wide mouth while on the wing. Note the flat lamellate bill of the ducks; they scoop up mud and water and strain their food from it. Note the firm chisel-like bill of the woodp.e.c.k.e.rs; they bore into hard wood for insects. Note the peculiarly crossed mandibles of the cross-bills; they tear open pine-cones for seeds. Note the long sharp slender bill of the humming-birds; they get insects from the bottom of flower-cups.

Note the bill and foot of any bird you examine, and see if they are specially adapted to the habits of the bird.

The tongues and tails of birds are two other structures the modifications and special uses of which may be readily observed and studied. Note the structure and special use of the tongue and tail of the woodp.e.c.k.e.rs; note the tongue of the humming-bird; the tail of the grackles.

=Flight and songs.=--The most casual observation of birds reveals differences in the flight of different kinds, so characteristic and distinctive as to give much aid in determining the ident.i.ty of birds in nature. Note the flight of the woodp.e.c.k.e.rs; it identifies them unmistakably in the air. Note the rapid beating of the wings of quail and grouse; also of wild ducks; the slow heavy flapping of the larger hawks and owls and of the crows; and the splendid soaring of the turkey-buzzard and of the gulls. This soaring has been the subject of much observation and study but is still imperfectly understood. The soaring bird evidently takes advantage of horizontal air-currents, and some observers maintain that upward currents also must be present. The princ.i.p.al hopes for the invention of a successful flying-machine rest on the power of soaring possessed by birds. The speed of flight of some birds is enormous, the pa.s.senger-pigeon having been estimated to attain a speed of one hundred miles an hour. The long distances covered in a single continuous flight by certain birds are also extraordinary, as is also the total distance covered by some of the migrants. "It is said that some plovers that nest in Labrador winter in Patagonia, their long wings easily carrying them this great distance."