Redwing Blackbird, originally uploaded by curlyson.

A redwing blackbird in courting display.

From the Google Institute of Artificial Smartness comes this link to the University of Michigan Museum of Zoology’s Animal Diversity Web listing for Agelaius phoeniceus (red-winged blackbird) that tells us:

Red-winged blackbirds roost and breed in a variety of habitats, but tend to prefer wetlands. They have been known to live in fresh and saltwater marshes. On drier ground, red-winged blackbirds gravitate towards open fields (often in agricultural areas) and lightly wooded deciduous forests. In winter red-winged blackbirds are most often found in open fields and croplands.

In addition to spot-on information like the above passage, this great web resource includes many more photos and blackbird calls. Go there!