Thanks to the springlike temperatures, I've begun sleeping with my windows open. Each morning, I am awakened by the boisterous songs of birds returning  from their winter homes in the tropics.

More than 360 species of birds make this annual migration between winter grounds in southern North America and Central and South America and breeding grounds in North America and the Arctic. Some of these birds are common - the ruby-throated hummingbird, gray catbird, purple martin and chimney swift. Others, such as the red-eyed vireo, scarlet tanager, wood thrush and Cape May warbler, may be familiar only to bird watchers.

The importance of migratory birds cannot be overlooked. Birds are our best natural insect control, eating tons of insects annually. As green leaves emerge each spring, so do millions of caterpillars and insects. Coinciding with this event, an array of birds - orioles, vireos, flycatchers, warblers and swallows - return to  feast upon the abundant insects.

With the arrival of songbirds and other migratory shorebirds, waterfowl and raptors comes the emergence of a particular breed of person - the bird watcher. Bird watching is becoming a leading recreational industry.

According to the 1996 National Survey of Fishing, Hunting and Wildlife-associated Recreation, almost 63 million Americans participated in wildlife-watching activities, including wildlife observation, feeding and photography. People participated in these activities around their homes or during trips. Ninety six percent of all residential wildlife watchers spent their time observing birds.

Seventy-five percent of all Americans who took trips specifically for wildlife-watching activities were checking out birds. They spent $29 billion on activities related to wildlife watching - buying goods or such services as travel, lodging and meals. Of that, $17 billion was spent on equipment, $9 billion on trip-related expenses and $3 billion on other items.

Despite their importance to our environment and economy, many bird species are declining. Large tracts of fields, forests and wetlands are disappearing to development. Today, many birds must nest in smaller, fragmented habitats. This leaves eggs and chicks vulnerable to predation by other birds, such as blue jays and crows, and mammals, such as raccoons and cats. Fewer chicks are surviving to replace adults killed by natural causes, including the perilous winter and spring migrations.

Although public land such as National Wildlife Refuges and National Parks are extremely important for wildlife, especially migrating birds, we cannot depend upon the small amount of federal land to provide all of the food and habitat birds need. Nationwide, 71 percent of the land is privately owned.

In the eastern United States that figure is closer to 90 percent.

To maintain the glorious diversity of songbirds, shorebirds, raptors and waterfowl, private landowners and state and local governments are needed to provide habitat. Private land in the United States is almost equally divided between range (27%), forest (27%) and crops (26%). The rest of the land is pasture and other land uses (20%). All of these lands can be managed to increase their value for wildlife while maintaining their current use.

Landowners can restore, enhance or protect habitat beneficial to birds and wildlife. Planting native vegetation provides wildlife with badly needed food and cover. For information, contact federal and state wildlife agencies for programs or information to assist with habitat enhancement and wetland restoration projects.

Winter habitats in Central and South America are also being altered and are disappearing, in some cases, faster than breeding habitats. If you're a coffee lover, consider buying shade-grown coffee. Coffee grown on clearcut plantations not only destroys rainforest, but also critical winter habitat for migratory birds. To learn about shade-grown coffee, contact the National Fish & Wildlife Foundation at: 202-857-0166, or the American Bird Conservancy at: 888-BIRD-MAG.

Cats that are allowed to roam free can also be a problem. Studies have shown that 20 percent to 30 percent of cats' prey is birds. There are at least 68 million pet cats in United States,  not including millions of stray and feral cats. Owners can reduce the number of birds maimed and killed by  keeping their cats indoors. This is also beneficial to cats.

Indoor cats are generally healthier and live longer and require fewer vet visits than those who roam outdoors.

Even with the ban on toxic pesticides like DDT, birds are still being exposed to harmful pesticides. Although most pesticides are intended to control specific pests, some harm or kill  nontarget species. Forty active ingredients in pesticides, the majority of which target insects, have been linked to bird die-offs. Most of the active ingredients known to be toxic to birds belong to one of three classes of chemicals: organochlorines, organophosphates and carbamates. To reduce the risk to wildlife, use pesticides very carefully.  If you must use a pesticide, choose one targeted specifically for your pest problem. If possible, use low-impact pesticides like dormant oils, insecticidal soaps or repellents free of organic solvents. Contact a local cooperative extension service for information.

To increase awareness of migratory birds, the second Saturday in May is designated as International Migratory Bird Day (IMBD). Here are a few activities celebrating these long distance fliers: o May 9: Blackwater National Wildlife Refuge, Cambridge, MD. Bird walks, displays and lectures. Call: 410-228-2693 o May 9: Patuxent Research Refuge, Laurel, MD. Bird & animal tours, Junior Duck Stamp Contest winners display, concert. Call: 301-497-5582.

  • May 9: Bombay Hook National Wild-life Refuge, Smyrna, DE. Bird counts, birding tour & slide shows. Call: 302-653-9345.
  • May 9-10: Chincoteague National Wildlife Refuge, Chincoteague VA. Tours, lectures by bird experts, junior birder and junior refuge manager programs, wildlife art contest, birdhouse building, decoy painting. Call: 757-336-6122.
  • May 9-10: Eastern Shore of Virginia National Wildlife Refuge, Cape Charles, VA. Wildlife walks, songbird census, exhibits and videos. Call: 757-331-2760.
  • May 16: Camden Yards, Baltimore. Baseball fans attending the Baltimore Orioles game that day can participate in an IMBD celebration and receive migratory bird posters, trading cards and other information. Fans will also get a chance to sample shade-grown coffee.

For information on IMBD events, contact the U.S. Fish &Wildlife Service, Office of Migratory Bird Management: 703-358-2318; the National Fish & Wildlife Foundation: 202-857-0166; American Bird Conservancy: 888-BIRD-MAG or your state's Partners in Flight Program (associated with state natural resource agencies). Check out the IMBD homepage at: www.americanbirding.org