I live on East Grand Traverse Bay in Traverse City, MI. The last few days I've noticed hundreds of ducks congregating about 20+ feet out from the frozen shore all in a straight band. If I look to the north or the south I can see more groupings of hundreds more. I read something about ducks swimming in a circle to prevent that area of the lake where they were doing this from freezing. This can't be the explanation because the Bay is too large and I would think the ducks know that the Bay is not going to freeze. The Bay is not frozen, just the shoreline area. Our average high temperature in the last several weeks has been in the teens. These appear to be wood ducks. They look like female mallards but that wouldn't make sense that they were all females. They are definitely not mergansers. If you could tell me why these ducks are congregating in this manner I would be most appreciative. My husband thinks it's a safety in numbers thing and that they are protecting each other from a predator like an eagle. However, I've never noticed this behavior in the summer.
Answer This is absolutely typical behavior. When ducks migrate south for the winter, they migrate in groups (as do geese and swans) and they remain in groups for the winter. That's partly for protection and partly to share food resources and partly because the habitat attracts them. In the summer they spread out and form pairs for courtship and egg -laying, so they are not found in groups. After breeding and raising young, they group up again and head south. That make sense?
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