A wonderful sign of fall is in the air: It's time to see v-shaped wedges overhead and hear the muffled, musical whistles of tundra swans.

The birds are coming from their summer nesting range, which mainly is north of the Arctic Circle. They are headed for their wintering range from Maryland to North Carolina, along the Atlantic Coast. They stop off in Minnesota in autumn to feed and rest for a few weeks. A good place to see hundreds or even thousands of tundra swans is the Mississippi River and its backwaters close to Minneiska, Minn. Also, check out the Brownsville area, where there is an overlook located three miles south of town.

Below are three entries from my nature notebook that may help interested observers this year understand tundra swan migration in the Twin Cities area and extreme southeastern Minnesota:

Nov. 11, 2014: Large flocks of tundra swans were seen flying southeast, all day, over Plato and Waconia and Bloomington.

Nov. 4, 2014: The first flock of tundra swans was observed flying high over Victoria and Chaska and heading southeast.

Nov. 10, 2013: An estimated 16,000 tundra swans were counted today on the Mississippi River between La Crescent, Minn., and the Iowa border.

Jim Gilbert's Nature Notes are heard on WCCO Radio at 7:15 a.m. Sundays. His observations have been part of the Minnesota Weatherguide Environment Calendars since 1977, and he is the author of five books on nature in Minnesota. He taught and worked as a naturalist for 50 years.