Molothrus ater, commonly known as the Brown-headed Cowbird, is native to North America. Its geographical distribution includes southern Canada, the United States, and northern Mexico.

The Brown-headed Cowbird typically inhabits open and semi-open areas such as grasslands, fields, and agricultural lands. It can also be found in forest edges, meadows, and scrublands. The species is often associated with environments that are modified by human activities, such as pastures and suburban areas.

Molothrus ater is known for its brood parasitism, laying its eggs in the nests of other bird species. This ecological behavior influences its presence in regions where host species are abundant. The species is highly adaptable, often thriving in habitats with fragmented landscapes where other bird species are present.