Birding - biology.

Birding - biology. I INTRODUCTION Birding, also known as bird watching, activity of observing and identifying birds in their natural environment for personal enjoyment or for educational purposes. Birders learn to recognize the distinctive feathers, colors, and structure of various bird species, as well as their calls, characteristic behaviors, and habitats. In the United States some 47 million people participate in birding, making it one of the most popular of all outdoor recreational activities. Birders often keep detailed lists of the bird species they have observed, the date the species was viewed, and the species' location, starting with those found in their own yards and neighborhoods. As their interest grows and their identification skills develop, many birders take pride in the growing list of species that they have viewed in locations further afield, such as other states or provinces, other countries, or even other continents. Many birders challenge themselves and one another to set records for the most species viewed in a 24-hour period, in an entire year, or over a lifetime. Collecting personal lists of identified birds can be more than just a pleasurable activity. In many cases these records also serve a scientific purpose. Skilled birders from around the world who participate as volunteers in research projects gather information on the health of bird populations. These studies often provide the best available data--sometimes the only data--about bird life in specific areas and during specific seasons. In this way data gathered by birders may play an important role in determining land use and wildlife-management policies aimed at preserving birds and their habitats. II HISTORY OF BIRDING Birding in North America has its origins in the first half of the 1800s. The discoveries and publications of pioneering American naturalists such as Alexander Wilson, John James Audubon, Thomas Nuttall, John Kirk Townsend, and John Cassin excited interest in the bird life of the Americas and prepared the way for the modern scientific study of birds, known as ornithology. In 1872 American naturalist Elliott Coues made a key contribution to the field when he developed one of the first systematic lists of North American birds. This comprehensive list, which provided a means to standardize bird classification and naming, became the basis of the Check-List of North American Birds, first published by the American Ornithologists' Union (AOU) in 1886. Periodically revised and updated by the AOU, this checklist remains a valued reference for birders. As the 19th century drew to a close, scientific interest in birds grew alongside a new fad for using bird plumage in high fashion, particularly for women's hats. In addition, bird eggs were collected as a hobby, and a wider variety of birds were considered tasty delicacies. As a result of these trends, birds were slaughtered at unprecedented rates, eventually resulting in the extinction of the great auk, passenger pigeon, and Eskimo curlew, and the near-extinction of many others, including the trumpeter swan and many species of herons, egrets, and terns. Appalled by the widespread slaughter of birds, in 1886 George Bird Grinnell, then editor of Forest and Stream magazine, formed the country's first bird preservation organization. Named the Audubon Society in honor of American naturalist and painter John James Audubon, the organization attracted more than 38,000 members in its first three months. Unable to keep up with the large membership, Grinnell disbanded the organization in 1888. However, from 1896 to 1899, 15 states formed local chapters of Audubon societies. Society members forged an environmental movement to create legislation that would protect birds. Among the laws passed as a result of this environmental movement was the New York State Audubon Plumage Law (1910), which banned the sales of plumes of birds native to New York. In 1918 the Federal Migratory Bird Treaty Act was enacted to protect all native birds in the United States and Canada. Some technological innovations helped transform the scientific study of birds into a recreational hobby. The introduction of the automobile in the early 1900s, followed by extensive road construction, made it easier for people to travel to wilderness areas for recreation and to view wildlife. At about the same time, improvement in the quality of optical lenses made lightweight binoculars with strong magnification more readily available. Before the advent of modern binoculars, scientists were only able to identify birds that they had captured. But modern binoculars made it easy for scientists and nonscientists alike to identify birds in their natural habitat. American ornithologist Frank Chapman correctly predicted that these innovations would help birding grow into a popular hobby when he wrote in his prototype of the modern field guide Color Key to North American Birds (1903), "Identification of the bird in the bush is its sole end; an end, however, which we trust will prove but the beginning of a new and potent interest in nature." Chapman founded Bird-Lore magazine in 1899 (still published today as Audubon magazine), and it became the first publication to unite skilled amateur observers with scientists in order to further bird conservation and education. Chapman also founded the annual Christmas bird count in 1900 as an alternative to an annual holiday bird hunt. Today the National Audubon Society sponsors the Christmas Bird Count. As the largest and longest-running wildlife survey, it provides crucial details about the health of North American bird populations and their environment. Each year over 45,000 volunteers from all 50 states, every Canadian province, the Caribbean, Central and South America, and the Pacific Islands, count every individual bird and bird species over one calendar day (from midnight to midnight), within well-defined geographic areas. By the early 20th century, birding had developed as an outgrowth of strong field research and the careful bird classification performed in museums. A birder's goal soon became twofold. One goal was to make identifications of living birds under field conditions as accurate as those made from museum specimens. The second goal was to document the occurrence of birds to better understand bird migration and distribution. During the first half of the century, American ornithologists Joseph Grinnell, director of the Museum of Vertebrate Zoology at the University of California at Berkeley, and Ludlow Griscom, curator at the Museum of Comparative Zoology at Harvard University in Cambridge, Massachusetts, inspired new generations of observers to search for unusual birds, perfect bird identification techniques, and accurately record findings. One of these young birders was American naturalist Roger Tory Peterson, whose pocket-sized Field Guide to the Birds (1934) made birding accessible with schematic illustrations that clearly portrayed color patterns and distinctive marks. Throughout most of the 20th century, museums or conservation groups such as the National Audubon Society sponsored the only birding organizations. With the founding of the American Birding Foundation (ABA) in 1969, birders acquired a new voice in the form of the ABA's Birding magazine, which provides major fieldidentification articles, publication and equipment reviews, and site guides for top birding locations. III WHERE BIRDS CAN BE VIEWED Birds are found throughout the world. They have adapted to an amazing variety of habitats. More than 800 species of birds live in North America north of Mexico. In the United States, areas with varied topography, such as the states of Texas and California, provide a number of different ecosystems that can support almost 600 species. Even the most heavily populated urban areas offer a fascinating array of bird life across the seasons. For example, more than 100 bird species regularly nest within New York City, and more than 350 species have been identified, at one time or another, in New York City's Central Park. Birds also flourish in some of the most remote and seemingly inhospitable regions of the world. Over 230 bird species occur in icy Greenland, and 272 species have been documented in Canada's Yukon Territory, where temperatures can plunge to -46°C (-50°F) during the winter. Intentionally and unintentionally, humans have shaped living environments in ways that are well suited to the needs of many bird species. Starlings, house sparrows, swallows, and rock doves nest on buildings in cities, towns, and farms. The chimney swift has abandoned hollow trees for chimneys as a nest site in urban areas. Mallards and Canada geese--once exclusively wild, migratory species--now live year-round in the open spaces found in city parks and golf courses. Nearly all purple martins, a songbird species that once used the abandoned nests of woodpeckers or the natural cavities of cliffs or dead trees, now live primarily in structures specifically constructed for them by humans. The peregrine falcon nests on tall buildings in many cities. IV BACKYARD BIRDING Some birders travel around the world to view a rare bird, but most birders are content to view the varied species seen in their own backyard and nearby neighborhoods. To attract birds to a backyard, birders provide some or all of a bird's three basic needs--water, shelter, and food. Birders often study the feeding and nesting behavior of the birds they wish to attract. They then design their backyard so that it will be attractive from a bird's point of view. Landscaping yards with familiar native plants provides protective cover for birds, along with edible fruits, nectar-bearing flowers, nesting sites and materials, and places to forage for insects. The sounds of trickling or dripping water from birdbaths and small, sheltered pools attract birds. These water sources offer a window into bird behavior as birds flock to them to drink and bathe. Wood ducks, woodpeckers, tree swallows, and wrens are among the many species that use birdhouses, also known as nest boxes. These humanmade wooden structures provide a safe nesting environment, particularly in urban areas, where natural nesting sites may be limited. Ideally nest boxes should provide adequate ventilation, so that heat can escape, and proper drainage, so that the nest remains dry. A nest box with a removable panel permits easy cleaning at the end of the season so that rodents and other pests will not move into the nest. The size of the entrance hole of a nest box will also determine the type of bird that uses it. For example, house wrens require an entrance hole that is 3 cm (1.25 in) in diameter while a northern flicker requires a 6.3 cm (2.5 in) hole. Birders use different bird feeders depending on the type of birds that they wish to attract. Bird-feeding systems include simple platforms on a post, hanging tubes that dispense seeds, and suet and sugar-water feeders. A platform feeder with millet seeds attracts doves and sparrows, while a tube feeder filled with black oil sunflower seeds attracts goldfinches, chickadees, nuthatches, and titmice. Birds such as woodpeckers and bushtits that eat insects and other invertebrates are drawn to suet feeders. Hummingbirds flock to sugar-water feeders, but many birders find it more satisfying to lure them to their backyards with colorful flowering plants, such as trumpet vine and honeysuckle. Backyard birders help birds by cleaning feeders and nest boxes regularly to prevent pest infestation and exposure to parasites and infectious agents such as Salmonella bacteria, which may live in discarded food. Domestic cats are perhaps the greatest menace for birds. The American Bird Conservancy, based in Washington, D.C., estimates that cats kill hundreds of millions of birds each year. Cat owners can make their backyards a safe haven for birds by keeping cats indoors or in an enclosed area. Food sources, such as garbage or outside pet food dishes, should be removed so as not to attract neighborhood cats or stray cats. Locate feeders, birdbaths, and nest boxes away from brushy vegetation or other structures that cats can use to conceal themselves and ambush unwary birds. V BEYOND THE BACKYARD Although it is possible to see and enjoy many species of birds in the backyard or in neighboring landscapes, many birds have not adapted well to urban conditions and prefer more natural habitats. Birding excursions to rural areas, forests, and shorelines open up many new bird-viewing possibilities. Some of the common, widespread species that birders look for in farmlands, grasslands, and other open country include vultures, kites, northern harriers, ring-necked pheasants, burrowing owls, bobolinks, meadowlarks, and goldfinches. Forests are home to broad-winged hawks, ruffed grouse, winter wrens, many finches, and most species of owls, woodpeckers, flycatchers, thrushes, warblers, and tanagers. Many birds prefer ponds, stream banks, marshes, and wet meadows, among them grebes, herons and egrets, ducks, sedge and marsh wrens, common yellowthroats, several kinds of sparrows, and red-winged and yellow-headed blackbirds. Coastlines, large rivers, bays, and lakes are home to water birds such as loons, pelicans, cormorants, geese, ducks, gulls, terns, auks, and puffins. Birders visit all of these habitats in all seasons to view these birds in the wild and build their bird lists. As winter approaches, some birds prepare for migration to warmer areas where food is more plentiful. Knowledgeable birders learn the migration routes for the birds they wish to view, and they seek out favored places where birds congregate along that route. These sites may include areas where birds gather in preparation for a long flight, known as staging areas. Other sites are known as resting or refueling stops, landing sites after long voyages over water, and winter-feeding grounds. Bays, estuaries, and wetlands may hold tens of thousands of migrating or wintering waterfowl. Arctic-nesting shorebirds move north across North America in April and May, then south again after breeding, from July to September. At such times they may gather in small flocks at ponds, mud flats, shorelines, and wet fields, and sometimes in huge numbers at rich feeding areas along the coasts. Many migratory birds follow well-established routes, reappearing year after year at the same localities. Thousands of sandhill cranes regularly visit Nebraska's Platte River Valley in March and early April. Raptors in fall migration sail past Hawk Mountain in eastern Pennsylvania or Hawk Ridge in northeastern Minnesota. The Delta Marsh Bird Observatory, located at the south end of Lake Manitoba near Ottawa, Canada, is a primary fall stopover site for migrating songbirds, including yellow warblers, song sparrows, and American redstarts. Many migrant birds collect at promontories and coastal islands in the spring and fall, including such well-known birding hotspots as High Island, Texas; the Dry Tortugas, Florida; Cape May, New Jersey; Point Reyes, California; and Point Pelee in Ontario, Canada. Birders often travel to find birds that live only in certain regions, especially birds whose ranges barely reach the borders of the United States and Canada. Popular sites include southeast Arizona and the lower Rio Grande Valley of Texas, where birders can view bird species native to Mexico; south Florida, which hosts birds from the West Indies; and western Alaska and the Atlantic coast provinces of Canada, where birders can view birds of Eurasian and Arctic distribution. Certain bird species with very small populations can be found only in restricted areas. Whooping cranes, for example, are best viewed only in their wintering grounds at Aransas National Wildlife Refuge on the Texas coast, while Kirtland's warblers are rarely seen except in northern Michigan where they breed in jack-pine stands. Many birders join special tours just to view these two species. Likewise, birders go on organized boat trips to see ocean-going bird species, such as albatrosses, shearwaters, and skuas, which cruise the open seas for most of the year. VI HOW TO IDENTIFY BIRDS Identifying birds is one of the most challenging tasks that birders face. Identification can be challenging because the traits that distinguish one species from another are often subtle and difficult to observe. Different species of birds sometimes look alike, while birds of the same species may show marked differences between males and females, juveniles and adults, or summer and winter plumage. Accurate bird identification should be based on several aspects of the bird's appearance and reinforced by other indicators such as vocalization, behavior, and habitat. A Appearance Bird identification often begins with what birders call jizz (the general impression of size and shape that a bird conveys at first sight). Jizz is not a definitive identification technique, however, and must be confirmed by close and careful examination of the bird's size, structure, color, and patterning. One way for beginners to gauge the size of a bird is to compare it to a nearby object of known size. Judging size can sometimes be tricky, however, especially when the bird is at a distance and there are no other objects nearby for comparison. The structure of a bird's body, wings, tail, bill, or feet can help distinguish a bird. For instance, body and bill shapes can distinguish a gull from a plover on the same stretch of ocean beach. Raptors such as ospreys, bald eagles, and broad-winged hawks can be identified from their distinctive silhouettes in flight. Ospreys have long wings with an angled leading edge. The large head of the bald eagle projects well forward of the straight leading edge of its wings, and the ends of the wings have a squared-off appearance. The broad-winged hawk has a small head and short tail and its broad, pointed wings have a smooth outline. The shape of a bird's bill has evolved as a consequence of the type of food the bird eats, and this characteristic is a powerful aid to identification. Hawks, owls, and eagles have strong, hooked bills for tearing the flesh of small animals. The straight, thick bills of herons, egrets, and kingfishers enable them to seize or spear frogs, fish, and crayfish, which they then swallow whole. Many ducks have broad bills that act as shovels to dredge up and strain out roots, seeds, and small water life. The hummingbird uses its long bill to collect nectar located deep within flowers. The short, stout cone-shaped bills of cardinals and sparrows are adapted for gathering and cracking seeds. The colors of a bird's bill, legs, and feet are often different from species to species, providing good field marks. In certain species the eyes and areas of bare skin around the face and throat may be distinctively colored. However, coloration of these parts can also vary within a single species as a result of different geographic populations, breeding conditions, diet, and other factors. Feather patterns are also unique for most species. The upper parts and underparts of wings may show combinations of colors, sometimes in a characteristic pattern. A folded wing often shows one or two bars of a different coloration. The head may be distinctively patterned with crown stripes, eyebrows, eye rings, eye lines, cheek patches, and mustache-like marks. Many species exhibit pronounced differences of plumage between sexes, ages, and molt phases. Others show a great range of geographic variation, and some (such as the red-tailed hawk) may have strikingly different color differences among individuals in the same locality. Birders learn the distinctive coloration and patterns of all these plumages as if they were separate species. Plumage fading or wear, as well as fog, rain, and certain lighting conditions at dusk or dawn, can sometimes distort the external appearance of birds, leading to erroneous bird identification. B Vocalizations Bird vocalizations provide strong clues to a bird's identity, although identifying distinctive songs and calls in the wild requires patience, experience, an excellent memory, and a finely tuned ear. Many birds rarely leave the cover of dense vegetation, and experienced birders can identify many of these birds by their vocalizations alone. Certain other species, although easy to see, may be visually indistinguishable in the field. For these birds, their song or call are the most reliable means of identification. Commercial recordings of bird songs can help birders become familiar with certain vocalizations, but they do not take the place of long and diligent field experience. Attempts at mimicking the sounds that birds make can be a useful aid to memory. The most successful are those that capture a distinctive rhythm and cadence, for example the "witch-i-ty witch-i-ty witch-i-ty" of the common yellowthroat. Ultimately, however, it is the quality of a song (for example, whether it is fluted, reedy, whistled, or buzzy) that makes it unique. These qualities are the most difficult aspect to describe in words. C Behavior Characteristic behaviors can be an important part of bird identification. Birds have different ways of nesting, courting, foraging for food, swimming, walking, and flying. For example, some birds search for insects or berries exclusively on the ground. Others search for food in low vegetation or in the highest tree canopies. Many birds feed underwater using distinctive diving patterns. Some birds jump-dive into the water from a floating position. Others put their head and neck under water and look around before propelling themselves deeper into the water with their wings and feet in pursuit of fish. Locomotion patterns can also distinguish bird species. Some birds walk along the ground, others hop. Other birds bob their hind ends or pump their tails ceaselessly. During flight, herons and egrets fly with bowed wings, measured beats, and necks usually tucked back. Cranes, in comparison, fly with necks extended using a faster wing beat on the upstroke. D Habitat Birds tend to live in a particular habitat, from grasslands or evergreen forests to shrubby thickets or marshes. Learning these habitat associations helps birders distinguish between similar-looking birds that prefer different habitats. Habitat is a good indicator, but it is not an infallible identification characteristic. Birds do show up in odd places. VII BIRDING ETHICS The ABA recommends that birders follow a code of ethics intended to protect birds and their habitats as well as the rights of property owners and outdoor enthusiasts. Birders should care for the welfare of birds by protecting important bird habitats, by staying on designated trails to avoid disrupting wild habitats, and by not frightening birds out of trees or exposing them to danger in order to obtain a better view. During group outings, birders need to lessen or prevent the impact of a large group of people on the wilderness environment. Birders should limit the use of bird sound recordings and other methods to attract birds, particularly in areas with many other birders. These methods should never be used to attract birds that are considered threatened or endangered because bringing these birds more into the open may needlessly stress them and negatively affect their breeding behavior. It may also place them at higher risk from predators. The presence of rare birds should only be advertised to other birders if the area can be accessed with minimal disturbance to the bird. The nesting sites of rare birds should not be made public. Instead, birders should report the site to conservation authorities, such as the state or provincial department of wildlife. Birders also need to respect other humans as well as birds. They should not enter private property without permission, and they need to follow all the laws and regulations governing the use of roads and public areas. Birders should behave courteously to other birders and people with whom they share the wilderness. VIII EQUIPMENT AND RESOURCES Birding requires only a few basic tools. Binoculars bring the physical details of a far-off bird into focus. Beginners can have good results with inexpensive binoculars, although the most exacting birders often select expensive high-performance models. When using binoculars, avoid searching trees with binoculars. Instead, first search for a bird without binoculars. When a bird comes into view, keep the head still and raise the binoculars to the eyes to bring the bird into focus. Practice this technique to locate stationary objects, such as a tree branch, first. Locate larger objects with binoculars and then try finding smaller objects. Intermediate and advanced birders may want to use a spotting scope--a small telescope mounted on a tripod. Spotting scopes are ideal for viewing birds on the ground or on water, such as shorebirds and waterfowl. Camera equipment is a must for those who have discovered the joys of bird photography. In learning about birds, nothing substitutes for field experience, but there are other useful aids. The one indispensable tool is a good field guide, featuring detailed illustrations or photos of birds, range maps, and descriptive text. A good field guide will also provide clear identification clues and characteristic bird behaviors. A birdfinding guide that focuses on birds living in the birder's geographic area during all seasons will help birders find the best places to view birds. Many organizations provide support, information, and volunteer opportunities for birders. Chapters of the National Audubon Society, state and local bird clubs, and adult education programs frequently offer bird identification classes, public lectures on birds and birding, publications, and field trips. The American Birding Association serves dedicated birders in both Canada and the United States through its publications, conferences, scholarships for young birders, directory of volunteer opportunities, research programs, and other activities. This organization helps birders develop identification skills, test these skills in the field, and learn to practice careful record keeping and sound birding ethics. Bird Studies Canada, based in Ontario, Canada, and the Cornell Laboratory of Ornithology recruit volunteers to participate in local, regional, national, and international programs of research and education in support of bird conservation. The data collected by these volunteers help scientists track movements of bird populations and long-term trends in bird distribution and abundance. Contributed By: Hal Opperman Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. All rights reserved.