Walking his dog 10 days ago, Antioch resident George Niemasik spotted what he thought were swans on an inlet of Spring Lake near his home.
Getting closer, he realized the huge, exotic-looking birds were unlike anything he had seen.
"Really neat. Just so unusual," he said of what he later learned were American white pelicans on the northern Illinois stop of their spring migration to the Great Plains and southern Canada.
Among the largest birds in North America, the graceful fliers are known for a wingspan that can reach 9 feet. They have an improbably large bill and pouch that sets them apart from other waterfowl, such as loons that are on the same journey north.
"Together, they circle and rise. When the flock turns in the sky, it's a shimmery, silver white and it's stunning," said Sarah Surroz, director of conservation partnerships for Conserve Lake County.
Years ago, seeing the snowy white Gulf Coast birds on lakes in northern Lake County would almost have been like spotting a UFO. But their comings and goings have become part of an annual rite of spring.
Doug Stotz, a senior conservation ecologist at the Field Museum, said the birds were not seen in the Chicago area when he first arrived in Illinois in the 1980s.
"I think what we're seeing is an increase in the population, and with the increase in population, they're spreading out," Stotz said.
Like the bald eagle or sandhill crane, which have been making comebacks and now can be seen regularly along the Fox River and other locations, the American white pelican is no longer a stranger here. They are sparse in Cook County but are regulars on the Chain O' Lakes and lakes in McHenry, Kane and western Will counties, Stotz said.
There has been a clear increase in their numbers in the last two decades, he said.
And, the big birds provide stunning visuals as they fish in groups.
"It kind of looks like a ballet," Stotz said. "They're herding fish."
Steve Roche, who has lived on Spring Lake for 13 years, said he first saw the American white pelicans -- no more than a dozen of them -- about three years ago.
"This year, it seems to be thousands. It's been a lot of fun with the kids and my wife," he said.
Some birders have reported seeing some lakes blanketed with hundreds of the big birds.
Rena Cohen, president of the Lake-Cook chapter of the Illinois State Audubon Society, said she has seen 90 American white pelicans and 90 common loons on area lakes at the same time this year.
According to Stotz, other points of interest are that both sexes of the American white pelican have a plate on the top of their bills that is associated with getting in breeding condition. Their flight feathers are black and are visible only when their wings are spread.
Their migration is likely peaking and will end by early May, he said.
Several types of ducks, including the northern shoveler and bufflehead, also are passing through, as are land birds such as the yellow-bellied sapsucker, golden-crowned kinglet and yellow-rumped warbler, experts said.