Welcome Back, Red-Winged Blackbirds!

Every spring as the ice in cattail marshes starts to decay (the term for soft, melting ice), Red-winged Blackbirds return to their posts, flashing red epaulets and calling "Okalee!" to defend their patches of territory. Males return first, often before any open water is available, but females bide their time farther south until the weather and food supplies are more steady. Male and female red-wings look completely different. Many people have trouble believing they're really the same species! Why do you suppose males and females look and act so very different?

Male Red-winged Blackbird
Photo Courtesy Peter S. Weber

Female Red-winged Blackbird
Photo Courtesy Jim Stasz
Patuxent Bird Identification Infocenter.

Changing Meal Plans
Red-winged Blackbirds have been spending the winter eating mostly plants. But the moment they settle into their marshy breeding grounds, they'll switch their diet to mostly animals, because that is exactly when insects will suddenly become available.

Female redwings wait to come north until warmer, more predictable weather makes insects more reliably available. Females need a LOT of bugs to provide the protein and calcium necessary to lay eggs. Redwings start breeding earlier in southern marshes than in northern ones, except for a small population breeding all the way down in Central America. They won't start breeding until June in Costa Rica, even though they'll lay their eggs all the way up in Saskatchewan in mid-May!

Changing Boundaries: Where Are They?
When male redwings first return, it takes a while before they work out the boundaries of their territories. When females return, and again during the nesting season, these boundaries move. If a male gets so busy courting or feeding babies that he doesn't pay attention, another male might start moving in on him!

One way ornithologists figure out exactly where territory boundaries are is to make a precise map of a section of the marsh. This section, called the "study area," can be any size, just so the scientist (or student, like you!) knows exactly how big it is. Then the ornithologist watches crows or hawks flying over the marsh. The male blackbird makes alarm calls as the predator flies over.

It's an easy matter to locate the redwings making the alarm calls. Each male redwing sits conspicuously on cattails, watching for predators and keeping other males off his territory. And when he's agitated, he exposes his red epaulets. Whenever the ornithologist hears one of these alarm calls, they mark the map exactly where the male made the call. It doesn't take long to see where the most calls take place. These clusters of marks on the map show the territories.
Another way to figure out a Red-winged Blackbird's territorial boundaries is to make a Red-winged Blackbird "Action Figure" (decoy) and set it near a marsh. You'll know if you've placed it in or near a territory if any Red-winged Blackbirds try to chase it off! If your classroom is near a red-wing marsh, make some paper maché action figures that look just like red-winged blackbirds and try it!

Try This! Journaling Questions
  • Red-wings arrive in marshes just before (or close to) the time when frogs start calling. Why do you think the arrival of Red-winged Blackbirds on marshes coincide with frogs starting to call? (Learn more about frogs and toads here.)
  • When a redwing dies, it usually happens over the winter. That means some redwing territories won't have an adult male to return them this spring. If a good territory isn't claimed by last year's owner, what will happen to the empty territory? Try to think of three different possibilities for what happens to a red-winged blackbird territory that isn't taken over by last year's male.