Chroicocephalus philadelphia, commonly known as the Bonaparte's Gull, is native to North America. It breeds primarily in Canada, from central and southern Labrador, north-central Alberta, and across, through southern Northwest Territories and Yukon. During non-breeding seasons, it migrates to the United States, along the Pacific and Atlantic coasts, and as far south as the Gulf Coast.

During the breeding season, Bonaparte's Gulls inhabit boreal forests near lakes, ponds, rivers, and marshes. These areas typically feature cool to cold climates, with abundant aquatic vegetation. In the non-breeding season, they frequent coastal regions, estuaries, and large inland water bodies, which offer milder climates.

Bonaparte's Gulls are primarily insectivorous during the breeding season, feeding on insects and larvae found in freshwater habitats. Outside the breeding season, their diet broadens to include small fish, crustaceans, and other invertebrates, often feeding in flocks in coastal and offshore waters. The species plays a role in controlling insect populations during breeding and contributes to the aquatic food web dynamics throughout its range.