Bird Smart A small flash of yellow and black alights on the willow branch in front of you. For a moment, you glimpse a bird''s cocked head and bright eyes, then it''s gone. You stop in your tracks and marvel that something could be that beautiful. Many of us see something grand in the body of a bird. A bird''s fascinating behaviors, melodic songs, and majestic colors add beauty and mystery to our lives. We marvel at birds'' ability to fly, the way they travel from south to north and back again to precise locations, and the way they build their intricate nests with just their bills. Bird-watching has a magic like no other type of nature observation. It brings many to the woods, wetlands, and prairies to see a new or rare species and to reconnect with the land.

In fact, bird-watching is a billion-dollar industry in this country. It is a wonderfully simple yet rewarding hobby that is a great family activity. The only expense involved is a pair of binoculars or camera and whatever traveling you wish to do. You needn''t go far. It is not uncommon for a bird-watcher to see as many as 50 kinds of birds in their backyard. Birds make up a distinct group of animals that have feathers covering their bodies and scales covering their legs, reproduce by laying eggs, and have bills. Even though all birds share these characteristics, there is tremendous variety in their size, shape, and color. They range from the tiny, iridescent hummingbird, weighing one-tenth of an ounce (3 grams), to the largest bird, the ostrich, often weighing up to 300 pounds (137 kilograms).

Worldwide, there are over 11,000 species of birds. Of those, about 2,000 live in North America. The first birds appeared in the middle of the Jurassic Period of the dinosaurs approximately 150 million years ago (humans have been around only 2 million years). They have adapted to every imaginable habitat. We find some birds soaring over the oceans and some living exclusively in the highest branches of a rainforest. They each have body parts that allow them to take advantage of the food available in their habitat. The long necks of geese and swans enable them to feed on plants deep in the water. The dagger-like bills of herons are adapted for catching fish.

And the broad, flat wings of hawks permit their soaring flights in search of mice and snakes. There is wide variety in the diets of different species of birds. Some are seed eaters, others eat insects, and still others eat mammals or even other birds. Seed- and berry-eating birds inadvertently act as important dispersers of seeds. In fact, some seeds, such as the sumac, won''t germinate unless the outer seed coat is softened by going through a bird''s digestive system first--a process called scarification. Insect-eating birds provide natural controls for abundant insects such as grasshoppers. Birds of prey such as hawks and owls help to keep populations of rodents in check. Each bird species plays an important role in the food chain.

There are also interesting differences in how birds mate and raise their young. For most species, such as the great horned owl or the Canada goose, parenting is a job for both parents. For others, such as the mallard duck or ruby-throated hummingbird, it is strictly a female task. For still others, such as some sandpipers, only the male cares for the young. Some species, such as the cliff swallow, breed in social units, often up to several hundred birds in a colony. There is even a bird, the brown-headed cowbird, that has other birds hatch and rear its young. The cowbird parents take no part in incubating or raising their young. Many birds in North America do share a common reproduction cycle.

They breed in northern regions, then migrate south to winter in warmer climates. People who study birds professionally are called ornithologists (or-ne-thol''e-jests), but many amateur bird-watchers are so into their hobby that their knowledge could earn them honorary college degrees. In fact, ornithology is one of the few scientific fields in which amateurs contribute greatly to our knowledge. Some have become involved in bird banding, which is a specialized skill of catching birds and placing tiny metal rings marked with a number around their legs. The bird is then released, and if it is captured by another bird bander, the location and habitat are recorded. This information helps in learning about their flight patterns and habits. If you happen upon a dead bird with a band, you can report your finding to the North American Bird Banding Program at usgs.gov/labs/bird-bandinglaboratory.

php. At this website, you can also print a certificate of appreciation for your efforts. There is much to learn and explore at this website, which includes a database going back to the mid 1900s. Like so many other creatures, birds are under pressure from humans. The population of some species has fallen sharply. Humans'' desire for the coveted eggs, feathers, and meat of birds have contributed to the demise of some. In the 1890s, thousands of birds were killed so their feathers could adorn hats. Today, the Migratory Bird Treaty Act of 1918 offers protection for many migratory bird species.

The threat to them is no longer unsustainable hunting, at least in our part of the world. Rather, it is the destruction of habitats as natural places give way to human development, fueled by the huge population growth of humans. For example, the US population increases by 3 million people each year, and worldwide increases are 70-80 million per year. People need resources, for example housing, that put them in competition with birds and other animals. Since the 1970s, North America has lost an estimated 3 billion birds, which is about one in four birds. This loss is across all ecosystems, including your own backyard. The filling in of wetlands for expanding cities and agriculture has created a downward slide in duck populations. Other threats include the pollution of waterways and the increased populations of raccoons, skunks, house cats, and other suburban predators of bird eggs and young.

Many options are available to us to preserve bird populations. Planting berry-producing trees and shrubs will help to provide much-needed nesting habitats and also food for birds. While backyard bird feeding will not directly affect the preservation of birds, it is a way to learn more about the birds in your area. The more informed you are, the more you''ll want to learn of their need for habitats. Supporting organizations that preserve land and joining your local Audubon Society will contribute to reversing the trend of dwindling habitats.