In 2014, I first heard the whistled "fee-bee" song of the black-capped chickadee on Jan. 3 at 10:30 a.m. The air temperature was 9 degrees and the sky was overcast but bright on the shores of Lake Waconia.

In a clear, sweet whistle, the chickadee sounds two notes of equal length — the second tone is lower in pitch than the first, making a "fee-bee" sound. The second note frequently has a slight waver in the middle, as if the bird sings a "fee-beyee" rather than a "fee-bee."

Even on cold January mornings in northern Minnesota, chickadees can be heard whistling "fee-bee" over and over again. This sound lifts our spirits because it's considered one of the earliest signs of spring. Some people even interpret the call as "spring-soon," but that's a matter of speculation. Yes, we hear the chickadee's call most often in early spring, but we also hear it throughout the winter, in the summer, and on crisp autumn days.

Some listeners confuse this song with the well-enunciated but rather coarse "phoe-be" or "fi-bree" of the eastern phoebe, which is croaked rather than whistled. The eastern phoebe is a summer resident of the state, usually arriving in late March and leaving in September. You won't hear its call in January in Minnesota. On the other hand, the black-capped chickadee is a common year-round resident throughout Minnesota. Chickadees are gray birds about 5 inches long with black caps and throat patches plus white chests. They never tire of sunflower seeds at feeding stations. Their name comes from the bird's other call, the familiar "chika-dee, dee, dee, dee."

Jim Gilbert's Nature Notes are heard on WCCO Radio at 7:15 a.m. Sundays.