Nothing wholly admirable ever happens in this country except the migration of birds. -- American drama critic and essayist Brooks Atkinson

Something tells them it is time to go. A change in the weather, less daylight, differences in the habitat, a diminishing food supply. Whatever the signals are, they start one of nature's most awesome spectacles: the annual bird migration.Not all birds migrate, but those that do seem to instinctively follow a grand design that takes them north to find food and breeding grounds in the summer and south toward more hospitable habitats in the winter.

The mystery of how they do this -- how they can travel thousands and thousands of miles and yet return to places with pinpoint accuracy -- is still not completely understood. Birds appear to navigate by using the sun and the stars and some internal biological magnetic compass, but they also follow visual cues such as mountains and coastlines and rivers.

While much mystery remains, however, scientists are sure of some things. And one is that the Great Salt Lake plays a major part in the migration of a large number of bird species.

It is part of the largest flyway corridor in the United States, says naturalist Stuart McCandless. Birds that have wintered in Alaska and Canada and are now heading to the Gulf of Mexico or Central and South America use the lake and its environs as a resting and feeding spot along the way. "It gives them a chance to refuel, build up energy for the rest of the trip," he says. Some may even spend the winter here.

Which was why McCandless was at lake shore on a recent Saturday morning with a group of both avid and budding bird-watchers. The outing was sponsored by Red Butte Gardens as part of its nature education program.

This was not one of what might be called the frequent flier days, but enough birds were at the lake to keep watchers busy, and the outing provided a chance to learn about some new developments designed to improve life for migrating birds passing through this corridor.

The group visited the Inland Sea Shorebird Reserve, a wetlands area developed by Kennecott along the south shore of the Great Salt Lake.

When Kennecott needed to expand its tailings pile, provisions of the Clean Water Act required the company to replace wetlands that would be affected in that move with a new wetland area that covers 3,900 acres along the south shore of the lake.

"Lee Creek had been rerouted way back when the railroad came through here," explained Ann Neville, wetlands manager for Kennecott. "What we did was bring the creek back to its original flow." And they used natural topography to create permanent ponds in a system that provides for environments ranging from fresh water to almost as saline as the lake.

"It's impressive what adding water to this environment does, what a difference it makes," she said. They have done studies and bird counts. In 1995 and '96, about 5,000 birds came through this particular area. In 1997, after the creek was rerouted and improvements made, some 50,000 birds stopped by. "And this year, our first full season with all the ponds operational, we've already had more than 100,000 birds."

Monitoring will continue until 2003, said Neville. By then, she hopes that things will be established and going well enough that the area can be opened to limited public access. "We included three to four miles of hiking trails and a couple of blinds in our design," but the public won't be allowed into the area until monitoring is completed.

The main objective of the reserve, she said, is to increase migratory bird activity. And that's something members of the entire ornithological community are watching. According to the World Wildlife Federation, the Great Salt Lake area is considered one of the internationally important wetland sites that may be among the most vulnerable to global warming, affecting populations of Wilson's phalarope, American avocet, California gull, white-faced ibis and American white pelicans.

Wetlands are very important, says McCandless. Where birds will be at any given time is determined by a number of factors. Chief among them are food and water provided by wetlands.

A key component of Red Butte Gardens' educational mission is to let people know about the critical relationships between people and wildlife, says Jaculynn Peterson, public relations manager at the gardens. So, visiting a place like this is really exciting, she says. "We all have to learn to value and to take care of our wildlife. It's wonderful to see these birds in their natural habitat. It's so peaceful and serene."

On this particular morning, a few American avocets are sunning themselves in the middle of a pond. Some Northern shovelers drift along the far shore. Farther on, the group comes across a couple of pintails. "Pintail ducks are my very favorites," notes McCandless, "they are so elegant looking."

Some Canadian geese, with their distinctive profile, fly overhead. Someone spots a blue heron, but it is quickly gone. A shrike is added to the list, too. And then, all of a sudden, the sky is filled with a hundred or so American white pelicans, flying in elegant formations, heading almost due south.

They have probably been resting at one of the lake's islands and are now heading off to the Gulf of California, says McCandless. The group watches the pelicans for as long as they can be seen, reluctant to let go of the awesome sight.

What they have witnessed on this morning is pretty representative of late fall migration, says Frank Howe, a migratory bird specialist with the Utah Division of Wildlife Resources, who has also come on the outing. Most of the birds coming through now are probably heading down to western Mexico for the winter, but it depends on the species. Some will even stay here, if they can find food. "The pintails will probably move on; the shovelers may stay."

As for the avocets, this is actually part of their Northern breeding ground. "They are one of the earliest to arrive back; they show up in early April," says Howe. In the spring, there may be 100,000 of them at the lake. A lot of them nest at Farmington Bay, he says.

In addition to the shorebirds and water birds, the lake's south shore is an important winter habitat for raptors. Harriers, falcons, rough-legged hawks. "They come down from the Arctic and will spend the winter feeding on rabbits," says Howe.

So, on this particular Saturday morning, some birds are coming, some are going. "Great Salt Lake is the largest staging area for some of the world's most incredible creatures," says Howe. "It's an important link in the chain for a number of species; there's nothing like it in the rest of the U.S."

Some of these birds put in an incredible number of miles in a year. And they fly with such accuracy, he says. Once when Howe was involved with netting and tracking migrating songbirds, "the same birds showed up at the very same net four years in a row."

Migration, he says, is simply amazing.