Susan Young of Boynton Beach used to be a casual birdwatcher — until last weekend when she joined a group of more than 30 people on the inaugural free tour of one of the South Florida Water Management District’s manmade marshes near Wellington.

Like the rest of the group, Young spied numerous species of ducks and other birds flittering and calling among the cattails and hydrilla of Stormwater Treatment Area 1 East. The 6,500-acre former farm field off Southern Boulevard has been transformed into a wetland that uses plants to filter phosphorus from runoff flowing south into the Everglades. It also is a magnet for numerous birds — everything from bald eagles to blue-winged teal. It is one of six stormwater treatment areas constructed south of Lake Okeechobee.

“I think it’s wonderful,” Young said. “I’ve always enjoyed bird-watching, but only recently got into it seriously. The variety of ducks — I think this is fabulous. I’d like to get a little closer to these ducks.”

Young and other birders came prepared — with binoculars, spotting scopes, bird identification manuals and even apps for their cellphones. They were guided in a carpool along the levees surrounding the wetlands by Linda Humphries of the Audubon Society of the Everglades in West Palm Beach; water district recreation planner B.J. Kattel; and Channel 12 news reporter Chuck Weber, an avid birdwatcher.

“It’s a great place — you’ll see a lot of birds,” Kattel told the group as they set off.

STA 1 East is the second stormwater treatment area to be opened for public birding tours by the district. STA-5 in rural Hendry County opened to guided bird-watching in 2005, led by Margaret England of the Hendry-Glades chapter of the Audubon Society. Birders have flocked there by the busload ever since, identifying nearly 120 species in the 5,100-acre marsh.

Several of the STAs also are open to duck hunting — but not on the same days as the birding tours.

Almost from the moment the car caravan set off from the parking lot, birders observed a variety of species: red-shouldered and red-tail hawk, bald eagle, osprey, roseate spoonbill, white and glossy ibis, cormorant, great blue heron, egret, wood stork, limpkin, white and brown pelican and several kinds of ducks.

They also spotted several purple swamphens.