More than 5,600 geese in Seattle have been destroyed since 2000, when a federal judge ruled that the government could kill Canada geese in gas chambers set up on the back of trucks.

The killing means people can now "see and enjoy" the geese, but "not be slipping in poop everywhere," said Roger Woodruff, U.S. Department of Agriculture state director in Olympia.

While Woodruff and Seattle parks officials called the eradication program a success, some animal-rights activists have renewed their protests. They call the killings cruel and unnecessary, with nonlethal alternatives available.

Opponents, including the Humane Society of the United States and the Progressive Animal Welfare Society, or PAWS, advocate addling goose eggs, such as spraying them with vegetable or mineral oil which suffocates the embryos. Other control methods they suggest include planting thick shrubs to discourage the birds from coming ashore, and using dogs to chase the birds away.

"What they have never done in Seattle is a comprehensive program -- doing all of these things at one time for a long period of time," said Jennifer Hillman, a legislative coordinator for PAWS.

The city tried other methods before hiring federal wildlife agents to kill birds, said Seattle Parks and Recreation spokeswoman Dewey Potter.

"We hate having to do it," Potter said. "It's painful and we don't like it."

In years past, the city tried relocating birds, attaching a shiny fringe to docks to scare geese away and spraying a bitter-tasting grape-based substance to discourage birds from eating grass.

In downtown Seattle Tuesday, activists showed a video of federal agents shoving honking geese into a gas chamber in the back of a truck.

During June and July, agents herd the geese onto land at waterfront parks and into fenced pens. For the past three years, activists have staked out parks and chased the birds away if game agents appear.