OAK HARBOR, Ohio - Growing flocks of majestic swans are delighting visitors to the marsh region of Northwest Ohio, but there is a dark side to the large, white birds enjoying a population explosion in Ohio, and many places around North America.
The swans in question are not native tundra swans or trumpeter swans whose once-abundant numbers in North America dwindled precipitously due to overhunting and habitat loss. They are mute swans, an invasive species from Europe brought to America by the decorative garden trade as early as the 1800s. Unlike native swans, the mute swans are aggressive, territorial and are gobbling native marsh plants at an alarming rate. They often overgraze an area to the detriment of plant diversity, fish habitat, water quality, erosion control and vegetation needed by native fish and waterfowl.
Mute swans are the largest, most aggressive waterfowl species in the world. They're easy to identify, with orange bills with a black knob, unlike the black bills of native swans. More facts about them can be found here.
You can hear the difference between the invaders and native swans. The hiss and bark of a mute swan can't begin to match the melodious song of a tundra swan, or the deep, resonant, trumpet-like cry of the larger trumpeter swan. But mute swans are beautiful. Killing them raises the ire of animal lovers everywhere, a reason Ohio and other states have been quietly reducing mute swan numbers through egg addling and culling programs.
Mute swans are the largest, most aggressive waterfowl in the world. They are very territorial, attacking other water birds and even people. The big, white male birds even attack other mute swans as males try to establish dominance among the flock.
"The number of mute swans has increased substantially in the marshes around Sandusky Bay and East Harbor," said Jim McCormac, an avian education specialist with the Ohio Division of Wildlife. "Mute swans didn't jump the garden fence for a long time, just sort of sat in limbo. They're not just a Lake Erie problem now. We're seeing growing numbers of mute swans on wetlands and ponds around Columbus."
The culling programs have been severely criticized around Maryland's Eastern Shore and the Chesapeake Bay region, and now in Michigan. Critics have condemned a recent plan by the Michigan Department of Natural Resources to reduce Michigan's mute swan population from 15,500 birds to just 2,000 by 2030. Michigan's mute swan colonies began with a single pair brought to Charlevoix County in 1919, reported the MDNR.
The Ohio Division of Wildlife's control plan calls for killing only a handful of mute swans each year, and only on public wildlife areas. The Ohio wildlife agency is working with the U.S. Department of Agriculture's wildlife services division to create an updated mute swan management plan.
Mute swans were once protected by the Migratory Bird Treaty Act. Sen. George Voinovich of Cleveland tacked a rider on an omnibus bill in 2004 to remove them from the MBTA, allowing flocks to be culled.
In East Harbor, just east of Port Clinton, there were a few mute swans nesting and living in the area almost year round less than a decade ago. No one seems to know why the population suddenly exploded, but this week more than 70 of the big birds had gathered in East Harbor, feasting on weeds, chasing Canada geese, fighting with each other and hissing at people getting close to nests or their youngsters.
Shy native swans, ducks and geese can't match the territorial aggression or the appetite of mute swans, and quickly lose the battle over traditional nesting, resting and feeding areas.
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The mute swan population around East Harbor off Western Lake Erie, just east of Port Clinton, has soared to more than 70 of the large birds this week. As mute swans challenge and chase Canada geese, their large flocks have begun to disappear.
Mute swans have little fear of people, and sometimes attack while presumably defending nesting and feeding areas. Anthony Hensley, 37, of Villa Park, Ill., drowned in April, 2012 while checking mute swans kept on a condominium pond to keep geese away. Officials theorized Hensley was close to the swans, or their nest, when the birds attacked him and his kayak flipped over. Paddlers, swimmers, jet skiers and people walking the shoreline are commonly threatened by mute swans.
Sport hunting for mute swans has not been option. Wildlife officials fear a native swan could be mistaken for a mute swan, and there are toxicology issues concerning eating swans that feed in contaminated harbor areas. A Michigan poll found more than half of the respondents felt mute swans were a threat to the region, but that hasn't blunted the opposition to killing swans using federal guidelines.
Unlike Asian carp, sea lamprey, round gobies, zebra mussels and other noxious invasive species, swans are always going to be dramatically striking, and considered a beautiful addition to any pond or marsh. That is, until the aggressive, prolific birds begin to dominate an ecosystem to the detriment of habitat, and a wide range of native species of water birds, as well as challenging humans invading their territory.