Monday, September 26, 2016

Mute Swans in the U.S.

During our visit to Indiana Dunes National Seashore (on Lake Michigan), we stayed in a hotel along a small lake.  Opening the curtain one morning, we were surprised to find six mute swans (four adults and two gray-brown juveniles) lounging on its grassy shore; by later in the day, the swans were gone.

Native to Eurasia, mute swans were introduced to the U.S. in the late 1800s and early 1900s, utilized to adorn parks, zoos, private estates and golf courses.  Since that time, many have escaped captivity and feral flocks are found across northern latitudes of the country.  The largest congregations of mute swans inhabit the Northeast Coast (from southern New England to the Chesapeake Bay), the Great Lakes region and the Pacific Northwest.  They tolerate both fresh and saltwater habitats and feed primarily on aquatic vegetation; most do not migrate if open water is available.

Unfortunately, these large swans are very aggressive, often chasing native waterfowl from their nesting and feeding areas.  In addition, they have a voracious appetite and large flocks of mute swans can significantly damage aquatic ecosystems.  Various methods, including hunting and egg addling, have been used to control their population though such intervention is controversial; as always, the introduction of a non-native species imposes significant risk to the environment.