Too many mute swans in Connecticut have conservationists calling for some control measures, according to this story. The large white birds are a threat, scientists say, because they devour vegetation needed by native crabs, fish and waterfowl and also uproot additional plants while feeding. All mute swans in this country are descendants of birds imported from England in the 19th century.

In New York, the state Department of Environmental Conservation has a number of research plans aimed at gauging the “impact of mute swans on people, wildlife, and ecosystems.”

The Wildlife Trust is in the midst of a study looking at the swans’ impact on Hudson River vegetation. Here’s an earlier post about their study and pasted below is a story from January. (The story link in the earlier blog post apparently expired.)
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Wednesday, January 31, 2007

City:
State:
Section: NEWS
Page: 1B
From:
Source: STAFF
Edition: GWPR
Publication: The Journal News
Study seeks information about Hudson River swans

YORKTOWN

Someplace on the Jersey Shore right now there’s a mute swan who possesses a bit of ready-made schtick.

Researchers captured the long-necked white bird in August in Verplanck and strapped a Global Positioning System transmitter to his back. The bird spent several months along the Hudson River before heading for Long Island Sound.

He’s now near Toms River, N.J., where he could regale his fellow waterfowl with something beginning, “I just flew in from Pelham and …” He’s Swan No. 507 and he’ll be there the rest of the winter – or maybe not. That’s one of the questions Fred Koontz, the executive director of Teatown Lake Reservation, and his colleague, Susan Elbin of the Wildlife Trust, are trying to answer.

“People haven’t been doing the behavioral observations. We don’t know what happens,” said Elbin, who heads the trust’s New York Bioscape Initiative. Her work focuses on ecological issues in the metropolitan area.

The two began studying mute swans in 2004, trying to determine their habits and effects on the Hudson River estuary. Like all mute swans in this country, they’re descendants of ones imported from England in the late 19th century for their aesthetic value. Mute refers to the birds’ propensity to not be very vocal, although they can hiss or grunt.

The birds have been deemed a problem in the Chesapeake Bay in Maryland, where they annually gobble more than 9 million pounds of aquatic plants and threaten native birds.

Underwater plants in the Hudson, as in the Chesapeake, provide homes and food for young fish, crabs and other creatures. Any long-term disruption of the shallow beds can lead to fewer fish in the river and other problems, eventually upsetting the river’s balance.

“Understanding the ecology of the submerged aquatic vegetation has important ecological and economic benefits,” Koontz said.

Their study is happening in conjunction with the state’s look at the big birds. About 2,500 swans call New York home and their numbers are increasing each year by about 9 percent. The birds, imported long ago to grace private estates, are a common sight throughout the Lower Hudson Valley.

“It’s a non-native species that does have some potential for impact on other wildlife,” said Bryan Swift, a waterfowl biologist with the state Department of Environmental Conservation.

Swift said fenced-off areas of the Hudson’s bottom showed the birds removed significant amounts of vegetation outside of the enclosures compared to within them. Their droppings, he said, carry more fecal bacteria than Canada geese and have a greater potential to contaminate drinking water.

Koontz and Elbin’s study started in 2004 from a small plane. They flew monthly from the Tappan Zee Bridge to Troy, mapping where on the river the swans congregated. Favored spots included the south side of Croton Point, Annsville Creek and Rockland Lake.

During the summer, they rounded up eight birds – four near Kingston, two in Lake Meahagh in Verplanck and two in Rockland Lake – and strapped solar-powered transmitters to their backs. Money for the undertaking came from the National Fish and Wildlife Foundation, a Washington-based nonprofit, and from the Wildlife Trust in Manhattan.

Three transmitters stopped working. Every three days, a satellite beams down the latitude and longitude of the other swans’ movements. Four have been relatively stationary -two on Rockland Lake, one on the New Croton Reservoir and one on Lake Taghkanic in Columbia County.

Swan No. 507, though, has been on the move. In the midst of his sojourn from the Hudson River to the Jersey Shore, he hopscotched one day earlier this month from near City Island in the Bronx, across Queens (stopping briefly at the site of the 1964-65 World’s Fair) and into Jamaica Bay.

“That was a flying day. He was trucking,” Koontz said.

Koontz and Elbin see their research providing a “proactive rather than reactive” response to any future swan dilemma on the Hudson. They hope to be able to predict which vegetation beds the birds prefer, where they spend their lives and why.

Koontz said they weren’t surprised with No. 507’s flight to New Jersey. Swans fitted with numbered neck collars by the state have shown up in New Jersey and off Long Island. Where he goes in the spring, he said, is the question – one the $4,000 transmitter he’s wearing should help answer.

“Right now, we don’t have a clue really, do we?” Koontz said.