The muffled musical whistles of traveling flocks of tundra swans can be heard. Yes, we are again witnessing the miracle of migration in the large Vs of tundra swans over the Twin Cities and other parts of Minnesota.

The swans migrate by day and night. The mature swans are white with black bills and feet. The immatures are light brownish-gray with pink bills. At 3 feet tall, 10 to 19 pounds and a 7-foot wing spread, they are easy to identify.

Tundra swans are coming from their summer nesting and feeding range mainly north of the Arctic Circle. Flocks pause on Minnesota lakes to rest and assemble by the hundreds and even thousands on the backwaters of the Mississippi River near Minneiska, south of Wabasha, and in a similar area just south of Brownsville. There they rest and feed on water plants.

Last year by Nov. 7, an estimated 9,000 tundra swans had arrived on the Mississippi River and backwaters, 3 miles south of Brownsville where there is an overlook. These two Minnesota areas represent the largest concentration of tundra swans in the central United States.

The magnificent tundra swans will stay a couple of weeks and then probably a strong weather system could send them on the way toward their wintering range along the Atlantic Coast, where they are most abundant between Maryland and North Carolina.

We will observe these swans again, passing back our way between the end of March and into the first half of April.

Jim Gilbert's Nature Notes are heard on WCCO Radio at 7:15 a.m. Sundays. Gilbert is the author of five books on nature in Minnesota. He taught and worked as a naturalist for 50 years.