More birds are migrating through the Upper Mississippi River Wildlife Refuge, according to a new survey.
The U.S. Fish and Wildlife Service says 500,000 birds migrated through that region last fall, about 100,000 more than the previous year.
U.S. Fish and Wildlife Wildlife biologist Eric Nelson says the number has been steadily increasing over the past 10 years. But he says having such a large number of birds using one feeding spot isn't a good thing.
"We would like to see a more even distribution through the Upper Mississippi River by providing good habitat, so that anything that would be considered catastrophic wouldn't be. We'd have them more dispersed," he said.
Nelson says other lakes in Minnesota and Wisconsin have become unsuitable for ducks, which is one reason they are concentrating on the river.
Nelson also says the population of canvasback ducks has sharply declined, but biologists don't yet know why.