Last year we heard the first hollow, mournful cooing sound of the mourning dove on Feb. 25. Such wintering-over birds are usually first heard by the third week of February, as an early sign of spring. It's the male mourning dove that produces the distinctive four-part song — "coah, cooo, cooo, cooo."

Thirty-five years ago, a wintering mourning dove was a rare sight in the Twin Cities. Now they are quite common throughout the winter season at feeding stations in southern Minnesota. Most of the birds still head for the southern United States in autumn. But reports from avid birders confirm that the mourning dove's winter range is moving north year by year. Climate change and proliferating feeding stations probably account for the extended winter range.

Pairs of mourning doves are commonly seen in the summer on utility wires or along roadsides picking up gravel. These birds are a foot long, have small heads, long pointed tails, and are mostly gray and brown. Their flight is swift and direct, and the whistling of the wings is distinctive.

Mourning doves eat huge numbers of so-called weed seeds in fields and other grassy areas. In fact about 98 percent of their diet consists of seeds. They also eat berries and insects. At feeding stations they like millet and cracked corn scattered on the ground near trees or shrubs with low branches that offer protection and roosting spots.

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.