The Red-winged blackbird is a common songbird distributed widely throughout wetlands and associated habitats in North America. Iconic features of fresh and saltwater marshes, males announce themselves with territorial displays of loud "konkeree" songs and bright, yellow-edged red shoulder patches (epaulets) on otherwise glossy black plumage. Females are much less conspicuous, dusky-brown with streaked bellies and off-white eyebrows. The sexes are similar in size, averaging 22 cm in length and 64 grams. Red-winged blackbirds are generalist feeders, eating more insects and mollusks when they are abundant but with the majority of the diet consisting of seeds and other plant material. Male red-winged blackbirds have on average five and up to 15 females breeding on their territories; the species is a well-studied example of polygyny. These gregarious birds are also known for large communal roosts and for mobbing predators such as crows and hawks.