For National Geographic News
The massive mute swan is creating ripples on both sides of "the pond." In both the U.S. and Europe, groups want to control booming swan populations to prevent them from overwhelming other species. Others say the bird is being made a scapegoat for environmental damage caused by humans.
The mute swan is an unmissable bird. Beautiful, graceful, spotless white, and awesomely large, it draws admiring looks in lakes and parks across Europe and North America. But some people are rather less enamored. So much so that some in the U.S. even want the birds culled.
The trouble is that mute swan populations are booming on both sides of the Atlantic, and at the expense of much other wildlife, say government agencies, scientists, and sport fishers.
With wingspans topping out at nearly 8 feet (2.4 meters), the aggressively territorial species is one of the world's biggest flying birds.
In Britain the mute swan was considered a domesticated bird until the 20th century, having first been kept by 12th-century English kings who made them the centerpiece of sumptuous royal feasts. Yet wild populations have increased 250 percent since the 1960s, according to breeding-bird surveys in Britain.
A protected species, the mute swan got a further boost in the mid-1980s. Anglers were banned from using toxic lead weights, which swans were found to swallow while feeding. The ban fueled a large rise in swan numbers on rivers, particularly spring-fed, chalk rivers in southern England, which are protected under European legislation that covers key wildlife habitats.
But fly-fishers claim mute swans are stripping these rivers of water crowfoot, an aquatic plant crucial to trout and the insects they eat.
"Many invertebrates use water crowfoot as cover and are much less successful if there isn't any," said Robin Mulholland, chairman of the Wiltshire Fishery Association, which represents the region's chalk river fly fishers. "It's also important in terms of defining territories for trout."
Mute swans—which each eat upward of four and a half pounds (two kilograms) of water crowfoot per day—may also be jeopardizing one of Britain's rarest mammals, the water vole, said Allan Frake. Frake is a biologist with the Environment Agency, the main government agency responsible for protecting the environment in England and Wales.
"Swans eat the [water crowfoot], the water level drops, and then stoats [a type of ermine] work [the water voles'] holes in the riverbank," he said.
From Europe
Similar concerns exist in the United States, where mute swans were first introduced as ornamental birds from Europe and Asia in the 19th century. At least 14,000 mute swans now live along the U.S. Atlantic coast alone, according to the U.S. Fish and Wildlife Service.
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