Trumpeter swans surge back, face mute swan challenges

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Capital News Service

Credit: FWS

LANSING – Is it time to break out the brass band because trumpeter swans are surging back.
A 2005 Michigan survey, counted only 500, but wildlife experts say numbers are increasing.
Early settlers hunted the birds nearly to extinction in the 1800s — using them to make powder puffs and feathered hats. But lack of exact records makes it impossible to reliably estimate the original population.
Those settlers exported hundreds of thousands of carcasses, said Larry Gillette, wildlife manager of Minnesota’s Three Rivers Park District, where a successful restoration program started with five swans in 1973.
Standing up to 4-feet tall with an up-to-8-foot wingspan, trumpeter swans are the largest waterfowl in North America.
Their Great Lakes range includes neighboring Wisconsin, Ohio and Ontario, as well as New York and Minnesota.
There’s new evidence of the trumpeter come-back.
Preliminary results of a 2010 survey of Midwest states – from South Dakota to New York – are expected to yield 8,000 birds, said Joe Johnson, chief wildlife biologist emeritus of Michigan State University’s Kellogg Bird Sanctuary, who is compiling the findings.
The heart of their population is in the Great Lakes states, Ontario and Iowa, Johnson said, and numbers vary dramatically. For example, an early January survey tallied more than 5,000 migrating swans in Minnesota, but experts put the actual number at nearly 6,000 by taking migrating birds into account.
Yet the trumpeters’ continued resurgence faces a number of challenges, including competition in the natural world and habitat destruction.
In February, the Michigan Natural Resources Commission voted 3 to 2 to make it illegal to rehabilitate the invasive mute swan, a major rival of the trumpeter.
Johnson said mute swans were deliberately brought to the state “as ornamental birds, and they got away from us.”
The overpopulated invasive mutes compete with the trumpeters by taking up preferred nesting spots and bullying them, according to some experts.
A Department of Natural Resources and Environment report to the commission described the mutes as “voracious feeders, which has resulted in the disturbance and destruction of submerged aquatic vegetation, a valuable food source for native waterfowl and other wetland species,” including trumpeters, loons and Canada geese.
The report also cited state efforts to reduce the number of mutes, including egg and nest destruction.
Dave Sherman, a wildlife biologist at the Ohio Division of Wildlife, said, “They’re a definitely a problem and we’re trying to minimize their impact on the trumpeter’s success.”
However, MSU’s Johnson said the relationship between the two species is the other way around: “My experience has been that the trumpeter swans dominate the mute swan.”
In Michigan, Johnson said, trumpeters are intentionally released where no or few mute swans are present.
Another impediment is lack of sufficient trumpeter habitat – mainly wetlands.
Sherman said Ohio has lost 90 percent of its wetlands, limiting the swans that usually like large territories to themselves.
“We found that the birds are fairly adaptable and we’ve seen them in wetlands that are less than 20 acres,” he said, indicating they’ve adapted to the limited amount of suitable habitat in Ohio.
Ohio has listed the bird as endangered since 1996 and has about 150 to 200 trumpetersnow, including 30 nesting pairs, Sherman said.
Alice Rossignol writes for Great Lakes Echo.

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