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When springtime starts with sloppy mud, gray skies, and tepid weather, it’s hard to get excited about the season. No sound is better able to pierce this wet blanket than the ringing konk-la-ree call of a red-winged blackbird with its thrilling trill at the end. I’ve heard it everywhere lately, from a lakeside bike ride to my walk from car to office.
Red-winged blackbirds are year-round residents in much of their range, which stretches from the Yukon down to the Yucatan. The northern breeders, though, must migrate far enough south to find crop stubble with waste grain and weed seeds not buried by snow. They gather in large flocks of as many as several million birds, and fly up to 50 miles each day from the roost to foraging grounds.
For red-winged blackbirds in the Great Lakes region, this generally means about a 700-mile trip. That’s not far in comparison to our “neotropical” migrants like hummingbirds, flycatchers, thrushes, and warblers who fly thousands of miles to overwinter in Central and South America. Those birds are nectar or insect specialists, and can’t eke out a winter survival on seeds alone.
One advantage that staying in the neighborhood gives red-winged blackbirds is that they have a better idea of how this particular spring is progressing, and can adjust their migration schedule based on weather. Neotropical migrants have no way to tell that spring is coming early in the north, so they stick to more stable cues—like day length—to decide when to migrate. Weather still affects their progress, since a winter storm or unfavorable winds can cause a delay, but their timing tends to be more consistent.
Red-winged blackbird males overwinter even closer to home than the females, because they have good reason to get back north as early as possible. The first male often gets the best territory, and it’s their gloom-piercing call that seals the deal. Belligerent males display in a “song spread” that includes fluffing up feathers, spreading their tail, raising their shoulders, and flashing their red epaulets, all while singing at the top of their lungs. We may appreciate this colorful performance, but it is not friendly, and it is not for us.
While the flocks of males currently foraging in yards and under bird feeders are not on territories yet, they already singing loudly—warming up for the big show. Drab, brown females will follow later, after insects begin to hatch. The ladies need a high-protein, high-calcium diet to prepare for egg laying, and have no reason to risk getting caught in a blizzard.
Once they arrive, females will choose a male’s territory, and set up a smaller territory within it. As many as 15 females might nest in a single male’s territory, but the average is five. Nests are built low to the ground, and are suspended among some upright stems of marsh plants. Females wind stringy plant material, wet leaves, and decayed wood into a bowl, and the line it with soft, dry grass.
This habitat requires a couple special adaptations. The most visible is the brown-streaked plumage of the females—perfect for staying camouflaged in the thickets. Those feathers are also extra sturdy, because living among rough cattail stems could result in undue wear and tear. In addition, both sexes have sturdy leg muscles that allow them to perch with each foot on a different cattail and do the splits.
Red-winged blackbirds also have long digestive tracks, which allow them to eat a wide variety of foods. In the summer, though, when their diet focuses on insects, their gizzards will shrink, only to get more muscular again when late summer seeds become ripe.
Late summer seems worlds away, though, as snow falls in the mud puddles and weed seeds get re-buried. The migrating flocks of red-winged blackbirds must be on the move again, looking for spring. When they find it, we can be sure they’ll sing a ringing konk-la-ree to let us know.
For over 45 years, the Cable Natural History Museum has served to connect you to the Northwoods. Come visit us in Cable, WI! Our new phenology exhibit: “Nature’s Calendar: Signs of the Seasons” will open May 1, 2016.
Find us on the web at www.cablemuseum.org to learn more about our exhibits and programs. Discover us on Facebook, or at our blogspot, http://cablemuseumnaturalconnections.blogspot.com.