Some people say that the red-winged blackbird is the most common bird in North America. It certainly is widespread in the summer, when it nests in the wetlands of every state and province on the continent. Yet, in winter, they are gathered large flocks, along with other species of blackbirds, mostly in central and southern US.
March is the time when redwings are on the move toward their breeding grounds, with the males leading the charge. Sometime during the month, the familiar cong-gor-ee song will be heard for the first time of the year in most wetlands.
Dominant males arrive first to stake out the best habitats. Lesser males have to settle for the edges.
A couple of weeks later the females arrive. It is the female, however, that decides where and with whom she will breed. Red-winged blackbirds are colonial nesters, and one male may have as many as 15 females in his harem.
It is surprising that if there are backyard bird feeders near a redwing breeding ground, males may fly frequently from the wetland to the feeders, grab a seed or two, and then quickly return to the territory to ward off any competition. It appears that the feeders are a common ground, because there is usually no fighting while feeding. Females are rarely seen at feeders, particularly early in the season, when they are busy building nests, incubating eggs and feeding young. By late summer, both females and youngsters may visit feeders.
-- George H. Harrison