Agelaius phoeniceus is found in most of North and much of Central America. It winters as far north as Pennsylvania and British Columbia, but northern populations are generally migratory, moving south to Mexico and souther U.S.

It gets its name from the distinctive red shoulder patches on the males, which are visible when flying or displaying.

When migrating north, they travel in single-sex flocks, with the males usually arriving a few days before the females. Once they reach where they plan to breed, the males stake out territories by singing. The male will defend its territory aggressively, against other Red-winged Blackbirds and other birds perceived as threatening, such as crows, ospreys and hawks, and even humans.

The males are territorial, defending up to 10 females. However, females frequently copulate with males other than their social mate, and often lay clutches of mixed paternity. Pairs raise two to three clutches per season, in a new nest for each clutch.