Quiscalus major, commonly known as the Boat-tailed Grackle, is primarily found in the coastal regions of the southeastern United States. Its range extends from Texas along the Gulf Coast to Florida, and up the Atlantic Coast to New Jersey. Additionally, a disjunct population can be found around southern California.

The Boat-tailed Grackle typically inhabits coastal marshes, mangroves, and estuaries. It thrives in wetland environments and is often associated with brackish or saline water bodies. The climate in these regions is generally warm and humid, with mild winters and hot summers.

Quiscalus major occupies a diverse ecological niche, often found in close proximity to human-altered environments such as agricultural fields, urban parks, and coastal towns where it forages for food. It feeds on a variety of resources, including grains, insects, small fish, and other invertebrates, displaying a high degree of foraging flexibility. This species is known for its opportunistic foraging habits and adaptability in different habitat conditions, which aids its survival and proliferation in coastal areas.