Red-winged Blackbirds, Agelaius phoeniceus, are passerine birds found in most of North and much of Central America. They breed from Alaska and Newfoundland south to Florida, the Gulf of Mexico, Mexico and Guatemala, with isolated populations in western El Salvador, northwestern Honduras and northwestern Costa Rica. They may winter as far north as Pennsylvania and British Columbia, but northern populations are generally migratory, moving south to Mexico and the southern United States.
Males have mainly black plumage with distinct red shoulder patches, or "epaulets", that give the bird its name. When at rest, males also display a bar of yellow just below the red shoulder patches.
Females have blackish-brown plumage on top and paler plumage beneath. They are considerably smaller than males and lack the trademark red shoulder patches.
Both sexes have extremely sharp bills.
Most red-winged blackbirds are migratory and travel in single-sex flocks with males arriving earlier than females to breeding areas to stake out and viciously defend their territorial claims. These birds practice polgyny (i.e. males having more than one female sexual partner), with males defending up to 10 females at a given time. Females tend to mate with other males that are not their social mates and often bear mixed paternity clutches (3 to 5 eggs). Eggs hatch in 11-12 days after being incubated by the female and chicks are hatched blind and naked. These birds develop rapidly, however, and are ready to leave the nest after only 10 days.
The Red-winged Blackbird inhabits grassy areas, and can be found in both wetland areas, such as freshwater and saltwater marshes, and dry upland areas, such as meadow, prairies, and old fields. They stake out territory by singing and defend this area aggressively from any perceived threats including other males, birds and even humans.