Dickcissel - Ecology

Ecology

Their breeding habitat is fields in midwestern North America. They migrate in large flocks to southern Mexico, Central America, and northern South America. They may occur as vagrants well outside of their normal range.

Dickcissels forage on the ground or in fields. They mainly eat insects and seeds. Outside of the nesting season, they usually feed in flocks. They are considered a pest by farmers in some regions because flocks can consume large quantities of cultivated grains.

The birds migrate to their breeding range rather late, with the first arriving only in May, with most birds only arriving in early June. They nest near the ground in dense grasses or small shrubs, or up to 3–4 ft (91–120 cm) high in bushes and trees. Males may have up to six mates, with most attracting only one or two, and several failing to attract any mates at all. Yet if such "bachelors" survive until next summer, they will get another try to attract females, as the partners only stay together for raising one brood. Dickcissels are thus among the few songbirds that are truly polygynous. When they leave for winter quarters by early August or so, what little pair bond existed during the summer is broken up.

Dickcissel populations frequently fluctuate in numbers, even to the extent that their range changes notably. In the early 19th century, Dickcissels expanded eastward, establishing a population in New England and the mid-Atlantic states that disappeared around the end of the century. Both appearance and disappearance were probably related to changes in land use.