Red-winged Blackbirds

Red-winged blackbirds, Agelaius phoeniceus, returned to my backyard a week ago and began singing to establish territorial boundaries.  In spring, males return first to stake out territories in high quality areas.  These marshy habitats have an abundance of food, water, and nest sites.  Females, returning a few weeks later, will select mates that can offer the best nest sites. 

The best nest sites are located in thick, marshy habitats.  Nests are an open cup woven from grass, reeds, and twigs, attached to a sturdy stem of grass or reed, one to two feet above the surface of the water.  Sites for males who arrive late may include more open water or be located in a grassy field with water nearby.  Nest sites in marshes are the best protection against predators, but any site can still be vulnerable to some predators including snakes and raccoons. 

A large area is not required for nesting, but more aggressive males will establish territories large enough to support several nest sites.  A female may have from one to three clutches each year, with a new nest constructed for each one.  Redwing blackbirds are a highly polygamous species.  A male commonly mates with two to four females nesting in his territory.  Females commonly mate with males from outside the nesting site territory for one or more of their clutches.

A redwing male is bold and protective of his territory during the breeding season.  They use their epaulets, the bright red patches on their shoulders, to send warning signals.  While overflying his territory, he may flash his epaulets to warn other males to stay away.  Redwings are not afraid to attack larger birds, animals, or humans that come too close and will flash their epaulets to signal their intent to give chase or fight to protect a site. 

Epaulets are also used in combination with singing to attract mates.  During the non-breeding season, males and females form large flocks that stay together for protection and to find food.  When males are members of a large flock, the epaulets remain hidden so as to not provoke responses from other birds.

Redwing blackbirds are one of the most abundant species in North America.  They are mainly ground feeders consuming insects, seeds, berries, fruit, and small invertebrates.  They do very well in urban environments, and easily consume seeds offered in backyard bird feeders.  As you enjoy walking in marshy areas, you can hear them calling until late summer when they follow the warmer weather south once again.