During breeding season the male bobolink's feathers are mostly black. It has a white rump, a white streak on the back and a yellow nape. In winter, he looks like a larger version of the female, with yellow-brown feathers.
Insects are the main diet of the bobolink in summer, but in winter, as it migrates south, it feeds on grain crops -- in former times particularly on rice.
The bobolink migrates at least 5,000 miles each year. It travels from Argentina to northern U.S.A. and Canada.
Males flirt with females by making bubbling songs. The female makes a nest on the ground and lays 5 or 6 eggs.