BLACKWATER NATIONAL WILDLIFE REFUGE -- Glenn A. Carowan Jr. figures he's tried just about everything -- propane cannons, shotgun blasts, Mylar balloons. He's even looked into buying border collies to shoo away a flock of 5,000 Canada geese that have settled year-round at this 25,000-acre preserve in Dorchester County.
So far, nothing has fazed the squatters, which seem to know a good thing when they find it. And the voracious birds, whose numbers are increasing each year, are wreaking havoc on fragile marsh habitat and crops meant to provide a fall and winter feeding ground for tens of thousands of their migratory cousins who will begin arriving from northern Quebec in about a month.
Carowan, who's managed the sprawling expanse of marsh and water for nearly a decade, says he's down to his last resort -- rounding up and killing most of the resident birds. The plan has raised the hackles of the Humane Society of the United States, which disputes the need to kill resident birds and has threatened court action.
"Why is it necessary to brand this group of birds as villains?" asks John Hadidian, the Humane Society's director of urban wildlife programs. "I think that most of the people who visit the refuge would want something less Draconian. What we want to see in 10 years is an ecosystem that is sustainable."
In Carowan's view, the refuge needs immediate help. "When I came here in 1989, we counted 359 birds; now there are 5,000," he says. "We never, never expected they would increase like this. In another year or two, they are going to jeopardize the whole purpose of the refuge -- which Congress established in 1933 to provide habitat for migratory waterfowl."
This summer, more than half the 300 acres of crops (mostly corn and clover) planted by the park service to provide food for migrating waterfowl have been reduced to stubble and weeds. Several fields have been planted twice and twice gobbled by geese.
"Basically, all you see now is morning glory, velvet leaf or cockle burr -- all the junk they don't like," Carowan says. "They've eaten our crops and gone on to the smart weed, wild millet, fall Panicum and dwarf spike rush, all the favorable plant species."
Officials already are worrying that picked-clean fields, combined with a drought-ravaged corn crop at private farms that surround Blackwater, will force migratory birds -- the main lure for nearly half-a-million visitors to the refuge each year -- to winter somewhere farther south.
"The resident population has just gotten totally out of control," says Ladd Johnson, a member of the Maryland Waterfowl Commission, an appointed panel that advises state environmental agencies. "We don't necessarily have to eradicate them, but certainly we have to reduce the number."
The problem, officials say, is that while the birds are Canada geese -- "they all wear the same uniform" -- the residents at Blackwater have never migrated and never will.
Most were born at the refuge, the descendants of nonmigrating geese brought to Blackwater or those taken by state and federal game wardens from illegal flocks.
Some of the first resident geese were brought to the refuge in the 1950s by state and federal officials to serve as live decoys to attract migratory flocks heading south for the winter.
Resident geese are causing similar problems up and down the East Coast, according to waterfowl experts with the Maryland Department of Natural Resources. In Maryland there are as many as 60,000 birds that often make trouble in suburban areas. Scattered throughout the Atlantic flyway are 1 million resident geese, probably outnumbering migratory geese, says William Harvey, a DNR researcher.
"Every resident goose is a product of man," Harvey says. "They aren't migratory geese who decided they didn't want to fly. They are wild, but they are not natural."
Humane Society officials dispute the very notion of attempting to attract some geese while killing off others of the same species.
Refuge officials have received necessary state permits, but still need the go-ahead from the U.S. Fish and Wildlife Service, a step that might prompt court action, warns the Humane Society, which last month won a court order requiring federal agencies to get such permits.
The animal welfare organization is critical of the park service plan to round up the birds next summer when they are molting and cannot fly, then dispose of them with carbon monoxide. The dead birds would be sent to processing plants and then distributed to shelters and soup kitchens.
"We have a fundamental problem with the idea that they plant crops to attract migratory birds, then make a determination about which are good birds and which are bad," said Patricia Lawson, a Humane Society attorney.
State and federal officials are struggling with other non-native species that have been introduced here, including mute swans, a European variety brought to the United States in the 1930s, and nutria, a South American rodent that looks like a muskrat on steroids.
At Blackwater, Carowan says, as many as 80,000 nutria have combined with resident geese, forming a devastating team that strips away marsh grasses, causing erosion of large tracts of marshland. Nutria eat the critical grasses from the bottom up and the geese devour new spring growth.
Wildlife officials say they have come to expect protest whenever lethal methods are used, but they see few alternatives.
"Hunting has not been effective, especially since the geese feed near areas where most of our visitors congregate," Carowan says. "We've tried addling [shaking the eggs to kill the embryos] but that is time consuming, just to get enough people out to find the nests before the eggs hatch. If somebody comes up with something that's workable, we'd be willing to try. But we have to do something."