Its name doesn't sound as nefarious as the red imported fire ant, as noxious as the giant hogweed or as pungent as the brown marmorated stink bug. In fact, a mention of the Canada goose conjures images of an innocuous, even beautiful, creature, especially in flight.

But like those other species, the Canada goose has been named Invader of the Month by the Maryland Department of Natural Resources, a designation given to a nonnative species wreaking havoc in the state.

To golfers, park managers and many suburbanites, Canada geese have become as nettlesome as the burgeoning deer population. The geese litter verdant lawns with feathers and droppings and can become aggressive while defending their turf.

Perhaps worst of all, they are damaging the environment, said Larry Hindman, the waterfowl project manager for the Maryland DNR. Some of the biggest problems they cause occur in the "destruction of wetlands, usually in the upper reaches of freshwater marshes," he said. "They've denuded important wetland plants and food sources of native wildlife."

There are "also safety problems during breeding season," he said, and the birds can be a road hazard. "But [they] are not nearly as dangerous to hit as deer."

The Canada goose population in Maryland jumped from about 25,000 in 1989 to 90,000 in 1998. Today, it's about 86,500, according to the department. "The sheer numbers of these birds have become intolerable, to say the least," Hindman said.

The Washington region got a sense of what an invasive species can do a couple of years ago when the northern snakehead fish, native to China and Korea, showed up in a Crofton pond. Since then, the snakehead has multiplied, and the aggressive species is feared to be disrupting the ecosystem and the delicate order of the food chain in some area rivers and creeks.

Invasive species "are plants and animals that are accidentally or intentionally introduced into the environment outside of their native habitat," according to a Department of Natural Resources brochure. In their new habitat, where they are often free of their natural predators and disease, they can cause all sorts of problems, such as killing native species.

Normally, Canada geese spend the spring and summer up north and then in the fall come south to the warmer climes around the Chesapeake Bay region. But now Marylanders "are seeing and hearing geese far too often -- and all year long," according to a department news release.

They are not just "lazy geese" that are too apathetic to return to Canada for the summer, the department said. Rather, they derive from pet geese used as live decoys in the 1930s for hunting. They may also be the descendants of geese brought in to repopulate the Eastern Shore around that time. Canada geese like to return to their birthplace and want to nest and feed in the same places, according to wildlife experts. That "makes it hard to eliminate geese once they become settled in a local area," Hindman wrote.

It's clear that the geese have laid claim to lots of places throughout the Washington region.

At the Jug Bay Wetlands Sanctuary in southern Anne Arundel County, the geese eat wild rice plants that are vital to native species, said Chris Swarth, the sanctuary's superintendent. The problem got so bad five years ago that workers put up four miles of wire fences to keep the geese out of sensitive areas.

"They damage the wetland ecosystem, and that in turn affects the other native animals that would depend on the habitat both for cover and food," Swarth said. "We'll have to manage the geese from here on out. It's going to be a constant issue."

The Maryland-National Capital Park and Planning Commission, which oversees parkland in Montgomery and Prince George's counties, has resorted to using two border collies to keep the geese away. Officials are also addling, or shaking, goose eggs so that they don't hatch, said Marion Joyce, a commission spokeswoman.

"If you remove the eggs or crush the eggs, the geese will either build another nest and reproduce or just reproduce more eggs," she said. With "egg addling, the geese are less likely to abandon the nest and make a new one."

Egg addling and euthanizing geese require a permit from the U.S. Fish and Wildlife Service because the geese are protected under the Migratory Bird Treaty Act. During the proper season, licensed hunters in Maryland are also allowed to kill Canada geese.

At the Needwood Golf Course in Rockville, a border collie named Daniel is used to chase off the big birds. In the early morning, he shoos them away, even jumping in the course's pond if necessary. And in the evening, after the geese have returned, he chases them again, said Brian Blake, the course superintendent.

Before the course had a dog, geese were everywhere, tearing up the greens and distracting the players. But the worst problem, Blake said, was the poop they left.

The Jug Bay Wetlands Sanctuary also appears to be making strides in fending off the geese. Thanks to hunts and the fencing, "the marsh is making a tremendous comeback," said Greg Kearns, a Patuxent River Park naturalist who has also worked with Jug Bay.

But the damage from the geese has been telling. Kearns said he had noticed that fewer birds, such as sora rail, redwing blackbirds and bobolinks, were nesting in the marshes. That's because the geese had taken over, devouring thousands of acres that would normally provide food and shelter to the other birds, Kearns said.

"It's just been incredible," he said. "We never dreamed they would cause this much damage. They have changed the entire composition of the marsh."

The Canada goose population in Maryland jumped from about 25,000 in 1989 to 90,000 in 1998, officials said. Canada geese have "denuded important wetland plants and food sources of native wildlife," said Larry Hindman, a DNR official.