A plan in New York state to eliminate all wild mute swans there by 2025 has drawn protests and petitions on all sides. While some see elegant white birds gliding across the water, others see a dangerous aggressor destroying the local ecosystem.
According to the state Department of Environmental Conservation, the swans — which don't honk but make hoarse, froglike grunts — are not native, and they destroy and attack native species. Amanda Rodewald, director of conservation science at Cornell University, says they've threatened loons in Michigan and least terns in Maryland.
"We are worried about them in New York because of the black tern population that we have," Rodewald says. Black terns there, she says, have only a few nesting colonies remaining.
The swans eat and pull out large amounts of submerged aquatic vegetation, destroying food sources for other birds. But what makes a nonnative species invasive?
Adam Welz, an ornithologist and filmmaker who lives in Brooklyn, says that when European songbirds were introduced in America, they failed to take. But in 1890, when a group of Shakespeare enthusiasts released 60 European starlings in Central Park, they multiplied into the millions.
"Most invasions, once they reached an explosive stage, are actually out of control," Welz says. "There is no way you can deal with them."
Stopping population growth before it explodes, he says, is "a prudent strategy to follow in general with invasive species."
Debating The Science
Mute swans were likely brought over in the late 1800s from Europe or Asia. In the 1970s, there were about 1,000 in New York; now there are 2,200. When the DEC studied the three places in New York where the swans are currently abundant, they found only one location, near Lake Ontario, where the species was growing rapidly.
David Karopkin, a defender of the swans and the founder of GooseWatch in Brooklyn, wonders how anyone can call that invasive.
"The science is faulty," Karopkin says. "It's weak at best."
Looking at the DEC proposal, Welz says he wishes the DEC had brought "a little more science to the party." Its approach has been tone deaf and legalistic, he says. Still, he is no defender of the swans. Just the other day, he says, he saw one knock over a toddler.
"No real harm done. He was a little dusty and upset, but we know that swans can be very dangerous," Welz says. "A man was drowned two years ago in Illinois by a swan — killed by a swan, a full-grown man."
Other critics of the DEC's plan wonder why it's focusing on 2,200 swans when there is so much natural habitat being destroyed by development. Rodewald agrees that ecosystems are facing huge problems — but, she says, we should act now before the swans are widespread.
"This is a situation where we can remove one of the threats, one of the stresses on these native ecosystems," Rodewald says.
There's another problem. If you go into a New York City park in May without a pair of binoculars, you may not see any of the more than 150 species of birds all around you. But a family taking a child to the park will see the swans and connect with them. They're big, they're visible, and they're full of romantic associations. They're important in people's lives, Karopkin says, "not just because they are beautiful; it is because people value and respect life."
Rodewald thinks it's just difficult for most people to think about large ecosystems, populations and habitats.
"The submerged aquatic vegetation," she says, "is inherently less charismatic than this beautiful swan."
Noting the thousands of comments and signatures on petitions, the DEC is revising its plan. It may decide to treat each area where the swans live differently, which may include nonlethal means of control.