CHAPTER XIII

BIRDS

[Illustration]

SUGGESTIONS.--The domestic pigeon, the =fowl=, and the English sparrow are most commonly within the reach of students. The last bird has become a pest and is almost the only bird whose destruction is desirable. The female is somewhat uniformly mottled with gray and brown in fine markings. The male has a black throat with the other markings of black, brown, and white, in stronger contrast than the marking of the female. As the different species of birds are essentially alike in structural features, the directions and questions may be used with any bird at hand. When studying feathers, one or more should be provided for each pupil in the class. The feet and bills of birds should be kept for study.

Does the =body of the bird=, like the toad and turtle, have a head, trunk, tail, and two pairs of limbs? Do the fore and hind limbs differ from each other more or less than the limbs of other backboned animals? Does any other vertebrate use them for purposes as widely different?

=Eye.=--Does the _eyeball_ have parts corresponding to the eyeball of a fish or frog; viz., cornea, iris, pupil? Which is more movable, the upper or lower _eyelid_? Are there any lashes? The bird (like what other animal?) has a third eyelid, or nictitating membrane. Compare its thickness with that of the other lids. Is it drawn over the eyeball from the inner or outer corner of the eye? Can you see in the human eye any wrinkle or growth which might be regarded as remains, or vestige, of such a membrane?

How many =nostrils=? In which mandible are they located? Are they nearer the tip or the base of the mandible? (Fig. 284.) What is their shape? Do the nasal passages go directly down through the mandible or do they go backward? Is the inner nasal opening into the mouth or into the throat?

The beak or =bill= consists of the upper and lower mandibles. The outside of the beak seems to be of what kind of material? Examine the decapitated head of a fowl or of a dissected bird, and find if there is a covering on the bill which can be cut or scraped off. Is the mass of the bill of bony or horny material? With what part of the human head are the mandibles homologous? (Fig. 284.)

[Illustration: FIG. 284.--SKULL OF DOMESTIC FOWL.

_q_, quadrate (“four-sided”) bone by which lower jaw is attached to skull (wanting in beasts, present in reptiles; see Fig. 277).]

=Ears.=--Do birds have external ears? Is there an _external opening_ leading to the ear? In searching for it, blow or push forward the feathers. If found, notice its location, size, shape, and what surrounds the opening. There is an owl spoken of as the long-eared owl. Are its ears long?

The =leg= has three divisions: the uppermost is the _thigh_ (called the “second joint” in a fowl); the middle division is the _shank_ (or “drumstick”); and the lowest, which is the slender bone covered with scales, is formed by the union of the _ankle_ and _instep_. (The bones of the three divisions are named the femur, tibiotarsus, and tarsometatarsus). The _foot_ consists entirely of toes, the bones of which are called phalanges. Is there a bone in each claw? (See Fig. 285.) Supply the numerals in this sentence: The pigeon has ____ toes, the hind toe having ____ joints; of the three front toes, the inner has ____ joints (count the claw as one joint), the middle has ____ joints, and the outer toe has ____ joints (Fig. 285). Is the thigh of a bird bare or feathered? The shin? The ankle? Where is the ankle joint of a bird? Do you see the remains of another bone (the splint bone, or fibula) on the shin bone of the shank? (Fig. 285 or 286.) Why would several joints in the ankle be a disadvantage to a bird?

[Illustration: FIG. 285.--LEG BONES OF BIRD.]

[Illustration: FIG. 286.--SKELETON OF BIRD.

_Rh_, vertebræ; _Cl_, clavicle; _Co_, coracoid; _Sc_, scapula; _St_, sternum; _H_, humerus; _R_, radius; _U_, ulna; _P_, thumb; _Fe_, femur; _T_, tibia. See Fig. 394.

=Questions:= Which is the stiffest portion of the vertebral column? How are the ribs braced against each other? Which is longer, thigh bone or shin? Compare shoulder blade with man’s (Fig. 399). Which is the extra shoulder bone? Compare tail vertebræ with those of extinct bird, Fig. 290.]

The _thigh_ hardly projects beyond the skin of the trunk, as may be noticed in a plucked fowl. The thigh extends forward from the hip joint (Figs. 286, 299) in order to bring the point of support forward under the center of weight. Why are long front toes more necessary than long hind toes? As the bird must often bring its head to the ground, the hip joints are near the dorsal surface and the body swings between the two points of support somewhat like a silver ice pitcher on its two pivots. Hence stooping, which makes a man so unsteady, does not cause a bird to lose steadiness.

The =wing= has three divisions which correspond to the upper arm, forearm, and hand of man (Fig. 286). When the wing is folded, the three divisions lie close alongside each other. Fold your arm in the same manner. The similarity of the bones of the first and second divisions to the bones of our upper _arm_ and _forearm_ is very obvious (Fig. 286). Explain. The _hand_ of a bird is furnished with only three digits (Fig. 287). The three palm bones (metacarpals) are firmly united (Fig. 287). This gives firmness to the stroke in flying.

[Illustration: FIG. 287.--HAND AND WRIST OF FOWL (after Parker).

_DG. 1-3_, digits; _MC. 1-3_, metacarpals; _CC. 3_, wrist.]

[Illustration: FIG. 288.--HAND, WRIST (_c_), FOREARM, AND ELBOW OF YOUNG CHICK (after Parker).]

That the bird is _descended from animals_ which had the fingers and palm bones less firmly united is shown by comparing the hands of a _chick_ and of an _adult_ fowl (Figs. 287, 288). The wrist also solidifies with age, the five carpals of the chick being reduced to two in the fowl (Figs. 287, 288). The thumb or first digit has a separate covering of skin from the other digits, as may be seen in a plucked bird. The degenerate hand of the fowl is of course useless as a hand (what serves in its place?) but is well fitted for firm support of the feathers in flying. The two bones of the forearm are also firmly joined. There are eighteen movable joints in our arm and hand; the bird has only the three joints which enable it to fold its wing. The wrist joint is the joint in the forward angle of the wing.

[Illustration: FIG. 289.--BREASTBONE AND SHOULDER BONES OF CASSOWARY.]

[Illustration: FIG. 290.--A FOSSIL BIRD (_archæopteryx_) found in the rocks of a former geological epoch.

=Question:= Find two resemblances to reptiles in this extinct bird absent from skeletons of extant birds.]

Since the fore limbs are taken up with locomotion, the =grasping function= has been assumed by the _jaws_. How does their shape adapt them to this use? For the same reason the _neck_ of a bird surpasses the necks of all other animals in what respect? Is the trunk of a bird flexible or inflexible? There is thus a _correlation_ between structure of neck and trunk. Explain. The same correlation is found in which of the reptiles? (Why does rigidity of trunk require flexibility of neck?) Why does the length of neck in birds correlate with the length of legs? Examples? (See Figs. 314, 315, 332.) Exceptions? (Fig. 324.) Why does a swan or a goose have a long neck, though its legs are short?

To make a firm support for the wings the vertebræ of the back are immovably joined, also there are three bones in each shoulder, the collar bone, the shoulder blade, and the coracoid bone (Fig. 286). The collar bones are united (why?) and form the “wishbone” or “pulling bone.” To furnish surface for the attachment of the large flying muscles there is a prominent ridge or keel on the breastbone (Fig. 286). It is lacking in most birds which do not fly (Fig. 289).

[Illustration: FIG. 291.--QUILL FEATHER.

_D_, downy portion.]

The =feathers= are perhaps the most characteristic feature of birds. The large feathers of the wings and tail are called _quill feathers_. A quill feather (Fig. 291) is seen to consist of two parts, the _shaft_, or supporting axis, and the broad _vane_ or web. What part of the shaft is round? Hollow? Solid? Is the shaft straight? Are the sides of the vane usually equal in width? Can you tell by looking at a quill whether it belongs to the wing or tail, and which wing or which side of the tail it comes from? Do the quills overlap with the wide side of the vane above or beneath the next feather? Can you cause two parts of the vane to unite again by pressing together the two sides of a split in the vane? Does the web separate at the same place when pulled until it splits again?

[Illustration: FIG. 292.--I, CONTOUR FEATHER. II, III, PARTS OF QUILL FEATHER, enlarged.]

The hollow part of the shaft of a quill feather is called the _quill_. The part of the shaft bearing the vane is called the _rachis_ (rā-kis). The vane consists of slender _barbs_ which are branches of the shaft (II, Fig. 292). As the name indicates (see dictionary), a barb resembles a hair. The barbs in turn bear secondary branches called _barbules_, and these again have shorter branches called _barbicels_ (III, Fig. 292). These are sometimes bent in the form of hooklets (Fig. 292, III), and the hooklets of neighboring barbules interlock, giving firmness to the vane. When two barbules are split apart, and then reunited by stroking the vane between the thumb and finger, the union may be so strong that a pull upon the vane will cause it to split in a new place next time.

[Illustration: FIG. 293.--A DOWN FEATHER, enlarged.]

There are =four kinds= of feathers, (1) the _quill_ feathers, just studied; (2) the _contour_ feathers (I, Fig. 292), which form the general surface of the body and give it its outlines; (3) the _downy_ feathers (Fig. 293), abundant on nestlings and found among the contour feathers of the adult but not showing on the surface; (4) the _pin_ feathers, which are hair-like, and which are removed from a plucked bird by singeing. The contour feathers are similar in structure to the quill feathers. They protect the body from blows, overlap so as to shed the rain, and, with the aid of the downy feathers retain the heat, thus accounting for the high temperature of the bird. The downy feathers are soft and fluffy, as they possess few or no barbicels; sometimes they lack the rachis (Fig. 293). The pin feathers are delicate horny shafts, greatly resembling hairs, but they may have a tuft of barbs at the ends.

A =feather grows= from a small projection (or papilla) found at the bottom of a depression of the skin. The quill is formed by being molded around the papilla. Do you see any opening at the tip of the quill for blood vessels to enter and nourish the feather? What is in the quill? (Fig. 291.) The rachis? A young contour or quill feather is inclosed in a delicate sheath which is cast off when the feather has been formed. Have you seen the sheath incasing a young feather in a molting bird?

There are considerable =areas= or tracts on a bird’s skin =without contour feathers=. Such bare tracts are found along the ridge of the breast and on the sides of the neck. However, the contour feathers lie so as to overlap and cover the whole body perfectly (Fig. 294).

[Illustration: FIG. 294.--DORSAL AND VENTRAL VIEW OF PLUCKED BIRD, showing regions where feathers grow.]

The shedding of the feathers is called =molting=. Feathers, like the leaves of trees, are delicate structures and lose perfect condition with age. Hence the annual renewal of the feathers is an advantage. Most birds shed twice a year, and with many the summer plumage is brighter colored than the winter plumage. When a feather is shed on one side, the corresponding feather on the other side is always shed with it. (What need for this?) A large _oil gland_ is easily found on the dorsal side of the tail. How does the bird apply the oil to the feathers?

[Illustration: FIG. 295.--WING OF BIRD.

_1_, false quills (on thumb); _2_, primaries; _3_, secondaries; tertiaries (dark) are one above another at right; _a_, _b_, coverts.]

[Illustration: FIG. 296.

_A_, point dividing primaries from secondaries; _B_, coverts.]

[Illustration: FIG. 297.--CEDAR WAXWING, with regions of body marked.

_S_, forehead; _Sc_, crown (with crest); _Hh_, nape; _K_, throat; _Br_, breast; _Ba_, lower parts; _R_, back; _Rt_, tail; _B_, tail coverts; _P_, shoulder feathers (scapulars); _T_, wing coverts; _HS_, primaries; _AS_, secondaries; _Al_, thumb feathers.]

In describing and classifying birds, it is necessary to know the names of the various external =regions= of the body and plumage. These may be learned by studying Figs. 295, 296, 297, 298. The quills on the hand are called primaries, those on the forearm are the secondaries, those on the upper arm are the tertiaries. Those on the tail are called the _tail quills_. The feathers at the base of the quills are called the _coverts_. The thumb bears one or more quills called the spurious quills. Is the wing concave on the lower or upper side? What advantage is this when the bird is at rest? When it is flying?

[Illustration: FIG. 298.--PLAN OF BIRD. _s_, center of gravity.]

[Illustration: FIG. 299.--POSITION OF LIMBS OF PIGEON.]

=Control of Flight.=--Did you ever see a bird sitting on a swinging limb? What was its chief means of balancing itself? When flying, what does a bird do to direct its course upward? Downward? Is the body level when it turns to either side? Birds with long, pointed wings excel in what respect? Examples? Birds with great wing surface excel in what kind of flight? Examples. Name a common bird with short wings which has a labored, whirring flight. Is its tail large or small? Does it avoid obstacles and direct its flight well? Why or why not? When a boat is to be turned to the right, must the rudder be pulled to the right or the left? (The rudder drags in the water and thus pulls the boat around.) When the bird wishes to go upward, must its tail be turned up or down? How when it wishes to go down? When a buzzard soars for an hour without flapping its wings, does it move at a uniform rate? For what does it use the momentum gained when going with the wind?

[Illustration: FIG. 300.

_a_, clambering foot of chimney sweep; _b_, climbing foot of woodpecker; _c_, perching foot of thrush; _d_, seizing foot of hawk; _e_, scratching foot of pheasant; _f_, stalking foot of kingfisher; _g_, running foot of ostrich; _h_, wading foot of heron; _i_, paddling foot of gull; _k_, swimming foot of duck; _l_, steering foot of cormorant; _m_, diving foot of grebe; _n_, skimming foot of coot. =Question:= Does any bird use its foot as a hand? (Fig. 320.)]

=Flying.=--When studying the quill feathers of the wing, you saw that the wider side of the vane is beneath the feather next behind it. During the downward stroke of the wing this side of the vane is pressed by the air against the feather above it and the air cannot pass through the wing. As the wing is raised the vanes separate and the air passes through. The convex upper surface of the wing also prevents the wing from catching air as it is raised. Spread a wing and blow strongly against its lower surface; its upper surface. What effects are noticed?

Study the =scales= on the leg of a bird (Fig. 300). Why is the leg scaly rather than feathered from the ankle downward? Which scales are largest? (Fig. 300.) How do the scales on the front and back differ? What can you say of the scales at the bottom of the foot; at the joints of the toes? Explain. How does the covering of the nails and bill compare in color, texture, hardness and firmness of attachment with the scales of the leg?

[Illustration: FIG. 301.--AN ALTRICAL BIRD, _i.e._ poorly developed at hatching. Young pigeon, naked, beak too weak for eating.]

[Illustration: FIG. 302.--A PRECOCIAL BIRD (well developed at hatching). Feathered, able to run and to pick up food. Precocity is a sign of instinctive life and low intelligence. A baby is not precocious.

=Question:= Is pigeon or fowl exposed to more dangers in infancy?]

=Draw= an outline of the bird seen from the side. Make drawings of the head and feet more detailed and on a larger scale.

Why does a goose have more feathers suitable for making pillows than a fowl? In what country did the domestic fowl originate? (Encyclopedia.) Why does a cock crow for day? (Consider animal life in jungle.)

=Activities of a Bird.=--Observe a bird _eating_. Does it seem to chew or break its food before swallowing? Does it have to lift its head in order to swallow food? To swallow drink? Why is there a difference? After feeding the bird, can you feel the food in the crop, or enlargement of the gullet at the base of the neck? (Fig. 304.)

Feel and look for any movements in _breathing_. Can you find how often it breathes per minute? Place hand under the bird’s wing. What do you think of its _temperature_; or better, what temperature is shown by a thermometer held under its wing? Do you see any connection between the breathing rate and the temperature? Test (as with the crayfish) whether a bird can _see_ behind its head? Notice the movements of the nictitating membrane. Does it appear to be transparent?

Watch a bird _fly_ around a closed room and review the questions on Control of Flight.

_Bend_ a bird’s leg and see if it has any effect upon its toes. Notice a bird (especially a large fowl) walk to see if it bends its toes as the foot is lifted. Pull the rear tendon in a foot cut from a fowl for the kitchen. Does the bird have to use muscular exertion to _grasp_ a stick upon which it sits? Why, or why not? When is this bending of the toes by bending the legs of special advantage to a hawk? To a duck? A wading bird? Why is a fowl safe from a hawk if it stands close to a tree?

[Illustration: FIG. 303.--HEAD OF WOODPECKER.

_c_, tongue; _a_, _b_, _d_, hyoid bone; _e_, _q_, windpipe; _f_, salivary gland.]

Do you see any signs of teeth in the bird’s jaws? Why are duck’s “teeth” (so called by children) not teeth? Can the tongue of a bird be pulled forward? (Fig. 303.) What is its shape? If there is opportunity, dissect and study the slender, bony (hyoid) apparatus to which the base of the tongue is attached (Fig. 303), the opening of the windpipe, or trachea, the slit-like opening of windpipe which is so narrow as to prevent food falling into the windpipe.

[Illustration: FIG. 304.--ANATOMY OF DOVE × ¹⁄₂.

_bk_, keel of breastbone; _G_, _g_, brain; _lr_, windpipe; _lu_, lung; _h_, heart; _sr_, gullet; _k_, crop; _dr_, glandular stomach; _mm_, gizzard; _d_, intestine; _n_, kidney; _hl_, ureter; _eil_, openings of ureter and egg duct into cloaca, _kl_.]

[Illustration: FIG. 305.--FOOD TUBE OF BIRD.

_P_, pancreas; _C_, cæca.

=Question:= Identify each part by means of Fig. 304.]

=The Internal Organs, or Viscera= (Figs. 304 and 305).--The viscera (vis′se-ra), as in most vertebrates, _include_ the food tube and its glands; the lungs, the heart, and larger blood vessels; the kidneys and bladder and the reproductive organs. The lower part, or gullet, is enlarged into a _crop_. It is largest in grain-eating birds. It is found in the V-shaped depression at the angle of the wishbone, just before the food tube enters the thorax. The food is stored and softened in the crop. From the crop the food passes at intervals into the glandular stomach. Close to this is the muscular stomach, or gizzard. Are the places of entrance and exit on opposite sides of the gizzard, or near together? (Fig. 304.) Is the lining of the gizzard rough or smooth? Why? Is the gizzard tough or weak? Why are small stones in the gizzard? Why do not hawks and other birds of prey need a muscular gizzard? The liver and pancreas empty their secretions into the intestines by several ducts a little way beyond the gizzard. Beyond the mouths of two cæca (Fig. 305) the many-coiled intestine empties into the straight rectum, which terminates in a widened part called the cloaca. Not only the intestine, but the two ureters of the urinary system and the two genital ducts of the reproductive system all empty into the cloaca (Figs. 304, 305).

[Illustration: FIG. 306.--POSITION OF LUNGS AND AIR SACS (Pigeon).

_Tr_, windpipe; _P_, lungs; _Lm_, sac under clavicle with prolongation (_Lh_) into humerus; _La_, sacs in abdomen.]

The =lungs= have their rear surfaces attached to the spinal column and ribs (_lu_, Fig. 304). They are connected with thin-walled, transparent _air sacs_ which aid in purifying the blood. When inflated with warm air, they probably make the body of the bird more buoyant. For the names, location, and shape of several pairs of air sacs, see Fig. 306. The connection of the air sacs with hollows in the humerus bones is also shown in the figure. Many of the _bones are hollow_; this adds to the buoyancy of the bird. The pulmonary artery, as in man, takes dark blood to the lungs to exchange its carbon dioxide for oxygen. Of two animals of the same weight, which expends more energy, the one that flies, or the one that runs the same distance? Does a bird require more oxygen or less, in proportion to its weight, than an animal that lives on the ground? Are the vocal cords of a bird higher or lower in the windpipe than those of a man? (Fig. 307.)

The heart of a bird, like a man’s heart, has four chambers; hence it keeps the purified blood separate from the impure blood. Since pure blood reaches the organs of a bird, oxidation is more perfect than in the body of any animals yet studied. Birds have higher temperature than any other class of animals whatsoever. Tell how the jaws, tail, and wings of the fossil bird Archæopteryx differed from living birds (Fig. 290).

[Illustration: FIG. 307.--POSITION OF VOCAL CORDS (_str_) OF MAMMAL AND BIRD.

=Question:= Does a fowl ever croak after its head and part of its neck are cut off? Explain.]

SUGGESTIONS.--In the field work, besides seeking the answers to definite questions, pupils may be required to hand in a record of the places and times of seeing a certain number of birds (20 to 40), with the actions and features which made each distinguishable. Also, and more important, each pupil should hand in a record of a careful and thorough outdoor study of one common species (see below) as regards habits, nesting, relation to environment, etc.

=Field Study of a Common Species.=--(_For written report._) Name of species. _Haunts._ Method of locomotion when not flying. _Flying_ (rate, sailing, accompanying sound if any, soaring).

What is the _food_? How obtained? _Association_ with birds of its own species. _Relation_ to birds of other species.

Where does it build its _nest_? Why is such a situation selected? Of what is the nest built? How is the material carried, and how built into the nest? Does the bird’s body fill the nest?

Describe the _eggs_. Does the male bird ever sit or otherwise assist female before hatching? Does it assist after hatching?

How long is taken to lay a sitting of eggs? How long before the birds are hatched? _When hatched_ are they helpless? Blind? Feathered? (Figs. 301, 302.) Do the nestlings require much food? How many times is food brought in an hour? How distributed? Even if the old birds sometimes eat fruit do they take fruit to the young? What do they feed to the young? How long before they leave the nest? Do the parents try to teach them to fly? Do the parents care for them after the nest is left? What songs or calls has the bird?

[Illustration: FIG. 308.--EUROPEAN TOMTIT’S NEST. What are the advantages of its shape?]

[Illustration: FIG. 309.--TAILOR BIRD’S NEST (India).

Instinct for nest building highly perfected.]

=General Field Study.=--(_For written report._) Name the best and poorest flyers you know; birds that fly most of the time; birds that seldom fly. Observe birds that pair; live in flocks. Does their sociability vary with the season? Do you ever see birds quarreling?

Fighting? What birds do you observe whipping or driving birds larger than themselves? Which parent do young birds most resemble? Name the purposes for which birds sing. Which senses are very acute? Why? Dull? Why? Can you test your statements by experiment? A partridge usually sits with 18 to 24 eggs in nest. About how long after laying first egg before sitting begins? Do several partridge hens lay in the same nest?

[Illustration: FIG. 310.--HOUSE WREN.]

_Haunts._--Name some birds that are found most often in the following localities: about our homes, in gardens and orchards, fields and meadows, in bushes, in the woods, in secluded woods, around streams of water, in thickets, in pine woods.

_Size._--Name birds as large as a robin or larger, nearly as large, half as large, much smaller.

_Colors._--Which sex is more brilliant? What advantage are bright colors to one sex? What advantage are dull colors to the other sex? Which have yellow breasts, red patch on heads, red or chestnut breasts, blue backs, black all over?

_Habits._--Name the birds that walk, jump, swim, live in flocks, sing while flying, fly in undulations, in circles, have labored flight.

Such books as Wright’s “Birdcraft” (Macmillan, N. Y.), Clark’s “Birds of Lakeside and Prairie” (Mumford, Chicago), and Pearson’s “Stories of Bird Life” (B. F. Johnson, Richmond), will be of great help. The last book is delightfully written, and is one of the few treating of bird life in the South.

=Economic Importance of Birds.=--Farmers find their most valuable allies in the class _aves_, as birds are the deadliest enemies of insects and gnawing animals. To the innumerable robbers which devastate our fields and gardens, nature opposes the army of birds. They are less numerous than insects and other robbers, it is true, but they are skillful and zealous in pursuit, keen of eye, quick, active, and remarkably voracious. The purely insectivorous birds are the most useful, but the omnivorous and graminivorous birds do not disdain insects. _The perchers and the woodpeckers should be protected most carefully._ The night birds of prey (and those of the day to a less degree) are very destructive to field mice, rabbits, and other gnawing animals. Some ignorant farmers complain continually about the harm done by birds. To destroy them is as unwise as it would be to destroy the skin which protects the human body because it has a spot upon it! It cannot be repeated too plainly that to hunt useful birds is a wrong and mischievous act, and it is stupid and barbarous to destroy their nests.

[Illustration: FIG. 311.--SCREECH OWL (_Megascops asio_).

=Question:= Compare posture of body, position of eyes, and size of eyes, with other birds.]

[Illustration: FIG. 312.--GOSHAWK, or chicken hawk.]

Injurious birds are few. Of course birds which are the enemies of other birds are enemies of mankind, but examples are scarce (some owls and hawks). Many birds of prey are classed thus by mistake. Sparrow hawks, for instance, do not eat birds except in rare instances; they feed chiefly upon insects. A sparrow hawk often keeps watch over a field where grasshoppers are plentiful and destroys great numbers of them. When a bird is killed because it is supposed to be injurious, the crop should always be examined, and its contents will often surprise those who are sure it is a harmful bird. The writer once found two frogs, three grasshoppers, and five beetles that had been swallowed by a “chicken hawk” killed by an irate farmer, but no sign of birds having been used for food. Fowls should not be raised in open places, but among trees and bushes, where hawks cannot swoop. Birds which live exclusively upon fish are, of course, opposed to human interests. Pigeons are destructive to grain; eagles feed chiefly upon other birds.

[Illustration: FIG. 313.--ROAD RUNNER, or chaparral bird (Tex. to Cal.). What order? (Key, p. 177.)]

If the birds eat the grapes, do not kill the birds, but plant more grapes. People with two or three fruit trees or a small garden are the only ones that lose a noticeable amount of food. We cut down the forests from which the birds obtain part of their food. We destroy insect pests at great cost of spraying, etc. The commission the birds charge for such work is very small indeed. (See pages 177-183.)

[Illustration: FIG. 314.--WOOD DUCK, male (_Aix sponsa_). Nests in hollow trees throughout North America. Also called summer duck in South. Why?]

The =English sparrow= is one bird of which no good word may be said. Among birds, it holds the place held by rats among beasts. It is crafty, quarrelsome, thieving, and a nuisance. It was imported in 1852 to eat moths. The results show how ignorant we are of animal life, and how slow we should be to tamper with the arrangements of nature. In Southern cities it produces five or six broods each year with four to six young in each brood. (Notice what it feeds its young.) It fights, competes with and drives away our native useful birds. It also eats grain and preys upon gardens. They have multiplied more in Australia and the United States than in Europe, because they left behind them their native enemies and their new enemies (crows, jays, shrikes, etc.) have not yet developed, to a sufficient extent, the habit of preying upon them. Nature will, perhaps, after a long time, restore the equilibrium destroyed by presumptuous man.

=Protection of Birds.=--1. Leave as many trees and bushes standing as possible. Plant trees, encourage bushes.

2. Do not keep a cat. A mouse trap is more useful than a cat. A tax should be imposed upon owners of cats.

3. Make a bird house and place on a pole; remove bark from pole that cats may not climb it, or put a broad band of tin around the pole.

4. Scatter food in winter. In dry regions and in hot weather keep a shallow tin vessel containing water on the roof of an outhouse, or out-of-the-way place for shy birds.

5. Do not wear feathers obtained by the killing of birds. What feathers are not so obtained?

6. Report all violators of laws for protection of birds.

7. Destroy English sparrows.

[Illustration: FIG. 315.--GREAT BLUE HERON. In flight, balancing with legs.]

=Migration.=--Many birds, in fact most birds, migrate to warmer climates to spend the winter. Naturalists were once content to speak of the migration of birds as a wonderful instinct, and made no attempt to explain it. As birds have the warmest covering of all animals, the winter migration is not for the purpose of escaping the cold; it is probably to escape starvation, because in cold countries food is largely hidden by snow in winter. On the other hand, if the birds remained in the warm countries in summer, the food found in northern countries in summer would be unused, while they would have to compete with the numerous tropical birds for food, and they and their eggs would be in danger from snakes, wild cats, and other beasts of prey so numerous in warm climates. These are the best reasons so far given for migration.

[Illustration: FIG. 316.--EUROPEAN SWALLOWS (_Hirundo urbica_), assembling for autumn flight to South.]

The =manner= and =methods of migration= have been studied more carefully in Europe than in America. Migration is not a blind, infallible instinct, but the route is learned and taught by the old birds to the young ones; they go in flocks to keep from losing the way (Fig. 316); the oldest and strongest birds guide the flocks (Fig. 317). The birds which lose their way are young ones of the last brood, or mothers that turn aside to look for their strayed young. The adult males seldom lose their way unless scattered by a storm. Birds are sometimes caught in storms or join flocks of another species and arrive in countries unsuited for them, and perish. For example, a sea or marsh bird would die of hunger on arriving in a very dry country.

[Illustration: FIG. 317.--CRANES MIGRATING, with leader at point of V-shaped line.]

The =landmarks of the route= are mountains, rivers, valleys, and coast lines. This knowledge is handed down from one generation to another. It includes the location of certain places on the route where food is plentiful and the birds can rest in security. Siebohm and others have studied the routes of migration in the Old World. The route from the nesting places in northern Europe to Africa follows the Rhine, the Lake of Geneva, the Rhone, whence some species follow the Italian and others the Spanish coast line to Africa. Birds choose the lowest mountain passes. The Old World martin travels every year from the North Cape to the Cape of Good Hope and back again! Another route has been traced from Egypt along the coast of Asia Minor, the Black Sea and Ural Mts. to Siberia.

=Field Study of Migration.=--Three columns may be filled on the blackboard in an unused corner, taking several months in spring or fall for the work. _First_ column, birds that stay all the year. _Second_ column, birds that come from the south and are seen in the summer only. _Third_ column, birds that come from the north and are seen in winter only. Exact dates of arrival and departure and flight overhead should be recorded in notebooks. Many such records will enable American zoologists to trace the migration routes of our birds. Reports may be sent to the chief of the Biological Survey, Washington, D.C.

[Illustration: FIG. 318.--APTERYX, of New Zealand. Size of a hen, wings and tail rudimentary, feathers hair-like.]

=Molting.=--How do birds arrange their feathers after they have been ruffled? Do they ever bathe in water? In dust? Dust helps to remove old oil. At what season are birds brightest feathered? Why? Have you ever seen evidence of the molting of birds? Describe the molting process (page 120).

[Illustration: FIG. 319.--GOLDEN, SILVER, AND NOBLE PHEASANTS, males. Order? (Key, p. 177.) Ornaments of males, brightest in season of courtship, are due to sexual selection (Figs. 321-7-9, 333).]

[Illustration: FIG. 320.--COCKATOO.]

[Illustration: FIG. 321.--BIRD OF PARADISE (Asia).]

=Adaptations for Flying.=--Flight is the most difficult and energy-consuming method of moving found among animals, and careful adjustment is necessary. For balancing, the heaviest muscles are placed at the lower and central portion of the body. These are the flying muscles, and in some birds (humming birds) they make half of the entire weight. Teeth are the densest of animal structures; teeth and the strong chewing muscles required would make the head heavy and balancing difficult; hence the chewing apparatus is transferred to the heavy gizzard near the center of gravity of the body. The bird’s neck is long and excels all other necks in flexibility, but it is very slender (although apparently heavy), being inclosed in a loose, feathered skin. A cone is the best shape to enable the body to penetrate the air, and a small neck would destroy the conical form. The internal organs are compactly arranged and rest in the cavity of the breast bone. The bellows-like air sacs filled with warm air lighten the bird’s weight. The bones are hollow and very thin. The large tail quills are used by the bird only in guiding its flight up and down, or balancing on a limb. The feet also aid a flying bird in balancing. The wing is so constructed as to present to the air a remarkably large surface compared with the small bony support in the wing skeleton. Are tubes ever resorted to by human architects when lightness combined with strength is desired? Which quills in the wing serve to lengthen it? (Fig. 296.) To broaden it? Is flight more difficult for a bird or a butterfly? Which of them do the flying machines more closely resemble? Can any bird fly for a long time without flapping its wings?

[Illustration: FIG. 322.--HERRING GULL. (Order?)]

=Exercise in the Use of the Key.=--Copy this list and write the name of the order to which each of the birds belongs. (Key, page 177.)

Cockatoo (Fig. 320) Sacred Ibis (Fig. 328) Screech Owl (Fig. 311) Nightingale (Fig. 325) Top-knot Quail (Fig. 329) Wren (Fig. 310) Apteryx (Fig. 318) Lyre bird (Fig. 327) Road Runner (Fig. 313) Ostrich (Fig. 332) Penguin (Fig. 330) Pheasant (Fig. 319) Wood Duck (Fig. 314) Jacana (Fig. 324) Sea Gull (Fig. 322) Heron (Fig. 315) Hawk (Fig. 312)

KEY, OR TABLE, FOR CLASSIFYING BIRDS (_Class Aves_) INTO ORDERS

ORDERS

A₁ =Wings not suited for flight=, 2 or 3 toes RUNNERS

A₂ =Wings suited for flight= (except the penguin)

B₁ _Toes united by a web for swimming, legs short_

C₁ Feet placed far back; wings short, tip not DIVERS reaching to base of tail (Fig. 300)

C₂ Bill flattened, horny plates under margin of BILL-STRAINERS upper bill (Fig. 323)

C₃ Wings long and pointed, bill slender SEA-FLIERS

C₄ All four toes webbed, bare sac under throat GORGERS

B₂ _Toes not united by web for swimming_

C₁ Three front toes, neck and legs long, tibia WADERS (shin, or “drumstick”) partly bare

C₂ Three front toes, neck and legs not long

D₁ Claws short and blunt (_e_, Fig. 300)

E₁ Feet and beak stout, young feathered, SCRATCHERS base of hind toe elevated

E₂ Feet and beak weak, young naked MESSENGERS

D₂ Claws long, curved and sharp, bill hooked ROBBERS and sharp

D₃ Claws long, slightly curved, bill nearly PERCHERS straight

C₃ Two front and two hind toes (Fig. 300)

D₁ Bill straight, feet used for climbing FOOT-CLIMBERS

D₂ Bill hooked, both bill and feet used for BILL-CLIMBERS climbing

=The Food of Birds.=--Extracts from Bulletin No. 54 (United States Dept. of Agriculture), by F. E. L. Beal.

The practical value of birds in controlling insect pests should be more generally recognized. It may be an easy matter to exterminate the birds in an orchard or grain field, but it is an extremely difficult one to control the insect pests. It is certain, too, that the value of our native sparrows as weed destroyers is not appreciated. Weed seed forms an important item of the winter food of many of these birds, and it is impossible to estimate the immense numbers of noxious weeds which are thus annually destroyed. If crows or blackbirds are seen in numbers about cornfields, or if woodpeckers are noticed at work in an orchard, it is perhaps not surprising that they are accused of doing harm. Careful investigation, however, often shows that they are actually destroying noxious insects; and also that even those which do harm at one season may compensate for it by eating insect pests at another. Insects are eaten at all times by the majority of land birds. During the breeding season most kinds subsist largely on this food, and rear their young exclusively upon it.

[Illustration: FIG. 323.--HEAD OF DUCK.]

[Illustration: FIG. 324.--JACANA. (Mexico, Southwest Texas, and Florida.)

=Questions:= What appears to be the use of such long toes? What peculiarity of wing? head?]

=Partridges.=--Speaking of 13 birds which he shot, Dr. Judd says: These 13 had taken weed seed to the extent of 63 per cent of their food. Thirty-eight per cent was ragweed, 2 per cent tick trefoil, partridge pea, and locust seeds, and 23 per cent seeds of miscellaneous weeds. About 14 per cent of the quail’s food for the year consists of animal matter (insects and their allies). Prominent among these are the Colorado potato beetle, the striped squash beetle, the cottonboll-weevil, grasshoppers. As a weed destroyer the quail has few, if any, superiors. Moreover, its habits are such that it is almost constantly on the ground, where it is brought in close contact with both weed seeds and ground-living insects. It is a good ranger, and, if undisturbed, will patrol every day all the fields in its vicinity as it searches for food.

[Illustration: FIG. 325.--NIGHTINGALE, × ¹⁄₃.

FIG. 326.--SKYLARK, × ¹⁄₃.

Two celebrated European songsters.]

=Doves.=--The food of the dove consists of seeds of weeds, together with some grain. The examination of the contents of 237 stomachs shows that over 99 per cent of the food consists wholly of vegetable matter.

=Cuckoos.=--An examination of the stomachs of 46 black-billed cuckoos, taken during the summer months, showed the remains of 906 caterpillars, 44 beetles, 96 grasshoppers, 100 sawflies, 30 stink bugs, and 15 spiders. Of the yellow-billed cuckoos, or “rain-crow,” 109 stomachs collected from May to October, inclusive, were examined. The contents consisted of 1,865 caterpillars, 93 beetles, 242 grasshoppers, 37 sawflies, 69 bugs, 6 flies, and 86 spiders.

[Illustration: FIG. 327.--LYRE BIRD, male.]

=Woodpeckers.=--Careful observers have noticed that, excepting a single species, these birds rarely leave any conspicuous mark on a healthy tree, except when it is affected by wood-boring larvæ, which are accurately located, dislodged, and devoured by the woodpecker. Of the flickers’ or yellow-hammers’ stomachs examined, three were completely filled with ants. Two of the birds each contained more than 3,000 ants, while the third bird contained fully 5,000. These ants belong to species which live in the ground. It is these insects for which the flicker is reaching when it runs about in the grass. The yellow-bellied woodpecker or sapsucker (_Sphyrapicus varius_) was shown to be guilty of pecking holes in the bark of various forest trees, and sometimes in that of apple trees, and of drinking the sap when the pits became filled. It has been proved, however, that besides taking the sap the bird captures large numbers of insects which are attracted by the sweet fluid, and that these form a very considerable portion of its diet. The woodpeckers seem the only agents which can successfully cope with certain insect enemies of the forests, and, to some extent, with those of fruit trees also. For this reason, if for no other, they should be protected in every possible way.

[Illustration: FIG. 328.--SACRED IBIS. (Order?)]

=The night hawk, or “bull bat,”= may be seen most often soaring high in air in the afternoon or early evening. It nests upon rocks or bare knolls and flat city roofs. Its food consists of insects taken on the wing; and so greedy is the bird that when food is plentiful, it fills its stomach almost to bursting. Ants (except workers) have wings and fly as they are preparing to propagate. In destroying ants night hawks rank next to, or even with, the woodpeckers, the acknowledged ant-eaters among birds.

[Illustration: FIG. 329.--TOP-KNOT QUAIL, or California Partridge. (West Texas to California.)]

=The kingbird, or martin=, is largely insectivorous. In an examination of 62 stomachs of this bird, great care was taken to identify every insect or fragment that had any resemblance to a honeybee; as a result, 30 honeybees were identified, of which 29 were males or drones and 1 was a worker.

=Blue Jay.=--In an investigation of the food of the blue jay 300 stomachs were examined, which showed that animal matter comprised 24 per cent and vegetable matter 76 per cent of the bird’s diet. The jay’s favorite food is mast (_i.e._ acorns, chestnuts, chinquapins, etc.), which was found in 200 of the 300 stomachs, and amounted to more than 42 per cent of the whole food.

[Illustration: FIG. 330.--PENGUIN OF PATAGONIA. Wings used as flippers for swimming.]

=Crow.=--That he does pull up sprouting corn, destroy chickens, and rob the nests of small birds has been repeatedly proved. Nor are these all of his sins. He is known to eat frogs, toads, salamanders, and some small snakes, all harmless creatures that do some good by eating insects. Experience has shown that they may be prevented from pulling up young corn by tarring the seed, which not only saves the corn but forces them to turn their attention to insects. May beetles, “dorbugs,” or June bugs, and others of the same family constitute the principal food during spring and early summer, and are fed to the young in immense quantities.

=Ricebird.=--The annual loss to rice growers on account of bobolinks has been estimated at $2,000,000.

=Meadow Lark.=--Next to grasshoppers, beetles make up the most important item of the meadow lark’s food, amounting to nearly 21 per cent. May is the month when the dreaded cut-worm begins its deadly career, and then the lark does some of its best work. Most of these caterpillars are ground feeders, and are overlooked by birds which habitually frequent trees, but the meadow lark finds and devours them by thousands.

[Illustration: FIG. 331.--Umbrella holding the nests of social weaver bird of Africa; polygamous.]

=Sparrows.=--Examination of many stomachs shows that in winter the tree sparrow feeds entirely upon seeds of weeds. Probably each bird consumes about one fourth of an ounce a day. Farther south the tree sparrow is replaced in winter by the white-throated sparrow, the white-crowned sparrow, the fox sparrow, the song sparrow, the field sparrow, and several others; so that all over the land a vast number of these seed eaters are at work during the colder months reducing next year’s crop of worse than useless plants.

=Robin.=--An examination of 500 stomachs shows that over 42 per cent of its food is animal matter, principally insects, while the remainder is made up largely of small fruits or berries. Vegetable food forms nearly 58 per cent of the stomach contents, over 47 per cent being wild fruits, and only a little more than 4 per cent being possibly cultivated varieties. Cultivated fruit amounting to about 25 per cent was found in the stomachs in June and July, but only a trifle in August. Wild fruit, on the contrary, is eaten in every month, and constitutes during half the year a staple food.

=Questions.=--Which of these birds are common in your neighborhood? Which of them according to the foregoing report are plainly injurious? Clearly beneficial? Doubtful? Which are great destroyers of weed seeds? Wood-borers? Ants? Grain? Why is the destruction of an ant by a night hawk of greater benefit than the destruction of an ant by a woodpecker? Name the only woodpecker that injures trees. If a bird eats two ounces of grain and one ounce of insects, has it probably done more good or more evil?

[Illustration: FIG. 332.--AFRICAN OSTRICH, × ¹⁄₂₀. (Order?)]