Although they are a habitat generalist, their favorite habitat is brushy areas and marshes, including salt marshes, across most of Canada and the United States. They also thrive in human areas, such as in suburbs, along edges in agricultural areas, and along roadsides. In southern locations, they are permanent residents. Northern birds migrate to the southern United States or Mexico, where there is also a local population resident all year round.
These birds forage on the ground, in shrubs or in very shallow water. They mainly eat insects and seeds. Birds in salt marshes may also eat small crustaceans. They nest either in a sheltered location on the ground or in trees or shrubs.
Singing itself consists of a combination of repeated notes, quickly passing isolated notes, and trills. The songs are very crisp, clear, and precise, making them easily distinguishable by human ears. The song sparrow usually repeats the same song many times before switching to a different song.