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Birds of Yosemite National Park (1954, 1963) by Cyril A. Stebbins and Robert C. Stebbins


INTRODUCTION

bird in flight

parts of a bird
PARTS OF A BIRD

HOW TO USE THIS BOOK

Illustrations have been designed to emphasize the more conspicuous field marks which serve as clues to recognition. An effort has been made to place the birds in characteristic poses, and a suggestion of habitat has been included. The figures after the name of the bird in each description are a measure of total length—beak to tail —in inches.

Descriptions are in semi-scientific terms with distinctive features emphasized in italic type. The diagram opposite showing the parts of a bird will help to clarify certain of these terms. Statements in the descriptions that have bearing on the range or habitat of a species apply to the Yosemite region or the Sierra Nevada and are not to be applied more broadly.

Key to the Yosemite Birds will be found on pages 70-74. The birds are segregated, first, on the basis of some conspicuous color or other characteristic and, second, on the basis of size, comparing with certain well-known birds. Hawks, eagles, owls, and hummingbirds are not included since most people recognize these birds as to group. The many pictures including the plate (see page 17) showing the hawks, vultures, and eagles in flight should suffice for identification.

Seasonal status. —Throughout the descriptive accounts the status of each species is given for the Yosemite region. Status refers to the time and duration of occupancy of an area—whether the bird is present throughout the year (R.—resident), during the winter period only (W.V.—winter visitant), during the summer only (S.V.— summer visitant), or sporadically for brief periods (C.V.—casual visitant). In the latter category are birds that pass through the area only in fall and spring migration or enter it during postbreeding upmountain movements (M.—migrant). To shorten the text the abbreviations have been used.

Area covered. —The Yosemite region, as referred to in this book, is the area of Yosemite National Park, the foothills immediately west of the park, and the slope from the Sierran crest to the shores of Mono Lake east of the park. At the present time 221 species have been reported within the park boundaries. Most of these have been described in the following pages. Species not described are those that have been seen only once or but a few times or about which there is doubt as to accuracy of identification. These undescribed forms are listed on page 63. The California thrasher, seen at lower elevations outside the park but not recorded within the park boundaries, is also described.

HOW TO STUDY BIRDS

First learn this quotation: “A bird in the heart is worth more than a hundred in a notebook.” Second, learn repose. Third, learn to listen. Fourth, learn to see accurately.

To study birds most successfully, proceed with your notebook and, if possible, a good pair of binoculars, with six- or eight-power magnification, to a place frequented by birds. Choose bright mornings or late afternoons for your study. Sit quietly and patiently and you may be rewarded. When a bird comes into view take a detailed description, noting size, colors, type of beak, and other characteristics. Walk slowly and quietly through the region selected for field study, stopping now and then. Birds are frightened by quick movements. Try imitating the call of a bird in distress by sucking the back of your wrist. Birds may appear.

One of the greatest pleasures the birds may offer you is through their songs; learn to listen and to recognize the birds’ voices, whether bird hunting or not. Whenever a new note is heard, if possible, trace it to its maker. Accurate recognition is often dependent upon the bird’s song or call.

Learn to see correctly and to interpret wisely.

SOME BIRD GROUPS

Characteristics of some of the bird groups may aid identification. These are pictured on pages 64-69 and briefly described below:

Hawks, eagles, and owls are usually of large size, have powerful hooked bills, usually stout legs, and long talons. Some hawks soar when foraging, others dart through thickets to pounce on their prey.

Owls are large-headed birds with broad, rounded wings; they usually forage at night.

Thrushes are brown above, sometimes spotted below. They are trim, timid birds that forage near the ground.

Vireos are small, active birds frequently with short, slender bills. There is a predominance of gray in the plumage.

Flycatchers range in size from 5 1/2 to 9 inches. They may be dull or bright in plumage, sometimes have wing-bars, an eye-ring, or white outer tail feathers. They have a marked habit of taking flight from a perch to return to the starting point on capturing an insect in the air. This act is often repeated. Raised feathers on the head often give the effect of a crest.

Wrens, with few exceptions, are small, brown birds usually with dark bars on tail and wings and in some species a whitish line over the eye. As a rule, wrens, when foraging, hold the tail upward at a sharp angle to the body. They forage near the ground.

Woodpeckers have stout, chisel-like bills, two toes in front and two behind (one exception), and stiff, pointed tail feathers. Black, white, and red are dominant colors. These birds forage around trunks and large branches of trees, bracing themselves with the tail as food is sought.

Sparrows are generally grayish or brownish with rather short, conical bills and they forage close to the ground.

Warblers, as a rule, are small, active, brightly colored birds with short, slender bills. The line over the eye, characteristic of vireos, usually is wanting on warblers; their relatively bright colors aid one in distinguishing them from vireos.

CONSERVATION OF BIRDS

Why birds are protected. —Ignorance of the value of our birds is common. Inaccurate observation condemns many birds unjustly. The farmer sees the meadowlark gather a few grains during the time of planting but fails to see the same bird eat grasshopper after grasshopper at other seasons and so the birds are hunted. The selfish eye of a fruit grower may see a woodpecker peck a hole in the barn but fails to see the bird eat harmful insects in the orchard.

Bird authorities of Massachusetts estimate one day’s work by the birds in that state to be the destruction of at least 20,000 bushels of insects. In every state, millions of insects are destroyed each day. While great numbers are destroyed through other natural agencies, just think, for a moment, of the number of insects the birds in the whole United States destroy in one day and in one year.

Hawks and owls have an undeserved bad reputation, due largely to the fact that the hawks are known as flesh eaters and the owls are abroad at night. Owls generally are beneficial, and the great horned owl is a destroyer of such pests as jackrabbits, cottontails, and pocket gophers. Analyses of the stomachs of hawks and owls has given evidence that they eat a variety of ground squirrels, rabbits, and mice.

Some bird laws. —Federal laws prohibit the importation of the English sparrow and other injurious birds and make it illegal to hunt or kill any wildlife in the national parks. Among many other birds protected under the Federal Migratory Bird Treaty Act are blackbirds, house finches, and shrikes.

California state law provides that all wild birds, excepting the house sparrow, crow, yellow-billed and black-billed magpie, scrub jay, Steller’s jay and starling, are protected. Similar laws protect the birds in other states. Where a species is not protected by state law but is protected by federal law, federal law holds.

Game birds which are hunted for food and sport may be killed only during the open season established by law. Of course, in national parks, birds and other animals are protected from hunting.

MIGRATION OF BIRDS

With seasonal changes, many birds move southward or northward, mountainward or valleyward as the case may be. They travel singly or in small or large groups.

During migration, birds take certain general directions to their destinations, guided by celestial cues and topographical features. Much remains to be learned regarding the forces which guide them in their migratory flight.

During migrations many birds die or are killed. Thousands of weaklings drop from exhaustion when long flights are taken without a stop. Storms often carry great flocks out of their courses. High buildings take their toll. Dead birds are found often at the base of the Washington Monument. Thus, in a way, migration strengthens the race of birds. The weak die. The strong survive. It is a form of natural selection.

At least nineteen species of shore birds breed near the Artic Circle and visit South America in the winter. More than a hundred species leave the United States to spend the winter from Mexico to South America.


Next: DistributionContentsPrevious: Preface

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Online Library: Title Author California Geology History Indians Muir Mountaineering Nature Management

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