GREEN SCENE: Winging it south

Thousands of tundra swans gathered to celebrate Thanksgiving. Photo courtesy of Stan Bousson

Tens of thousands of ducks, geese and swans migrate through our area each fall to dine on local veggies and sushi. Their trek to the southern wintering grounds is based upon Mississippi River ice-up.

The front line flocks of puddle ducks have departed for the sunny south while the diving ducks are trawling the open water of the main river channel, taking advantage of the slow-moving fish impacted by the cold temperatures.

Forty percent of all migratory North American waterfowl and shorebirds travel the Mississippi River Flyway that stretches 2,300 miles. This incredible journey by our winged friends takes them from their southern wintering grounds to as far north as Canada. The 261-mile-long Upper Mississippi River National Wildlife and Fish Refuge was established in 1924 to conserve riverine habitat on 240,000 acres for the benefit of many migratory wildlife species.

Migrating puddle ducks arrived in early September, with blue-winged teal leading the trek south. Puddlers are primarily vegetarian and insectivorous and prefer warmer water temperatures that support wetland plant growth and insect activity.

Migrating waterfowl are long-distance travelers. They endure many hazards, including ice storms, high winds, disease, predation and hunting pressure. Several blue-winged teal and coots were found dead in early September in lower Pool 13 at Potter’s Marsh. The National Wildlife Health Center confirmed these deaths were caused by trematodiasis, a parasitic infection. The parasites live within the non-native faucet snail and when eaten by waterfowl cause intestinal bleeding that results in death.

Trematodiasis is uncommon in our local area, with the last known occurrence in October 2012 when hundreds of coots and a few blue-winged teal died in lower Pool 13. The disease is common in northern Mississippi River areas, especially around La Crosse, where thousands of waterfowl die annually. The bad news is that the parasite is expanding its range by infecting other species of native snails, a delicacy of waterfowl.

Thousands of tundra swans arrived in early November and stayed to celebrate Thanksgiving. An unconfirmed report identified the swans congregated in support of our local turkeys that were protesting the Thanksgiving menu.

Snow geese, blue geese and white-fronts make up the more colorful goose arrivals. Sandhill cranes and red-winged blackbirds rounded out the variety of feathered migrants. Their voices echoed a musical rattle in the marshes.

Our local bald eagle trio are updating their nest decorum. We are hoping for a productive but non-dramatic nesting season. Two years ago, a pair of bald eagle pirates attacked the nest, killed the female, and made repeated attacks to kill the two chicks. Last year, a pair of great-horned owls made several midnight visits to the nest in what was a possible hostile takeover attempt. You can binge watch the escapades of the trio as they redecorate the nest and argue over proper placement of sticks. The eagle trio webcam can be viewed on the Stewards of Upper Mississippi River Refuge website, www.stewardsumrr.org, and is a partnership project with the Corps of Engineers and U.S. Fish and Wildlife Service.

We are truly fortunate to have such an abundance and variety of waterbirds at our back door. The waterfowl migration is underway and provides a great opportunity to view many species of ducks, geese and swans. Take the time to get out and enjoy the riverfront view.

Ed Britton is a wildlife refuge manager on the Upper Mississippi River National Wildlife and Fish Refuge and a volunteer at Bickelhaupt Arboretum.