Larus delawarensis, commonly known as the Ring-billed Gull, is native to North America. Its geographical distribution covers a broad range, primarily in the United States and Canada. This species is especially prevalent around the Great Lakes region, the inland and coastal waters of North America, and can be found in some parts of Central America during winter migrations.

The Ring-billed Gull inhabits a variety of environments, typically favoring freshwater and saltwater bodies such as lakes, rivers, coastal shores, and estuaries. These birds are commonly found in urban areas, and they have adapted well to human-altered landscapes. Their habitat usually includes open areas with access to water bodies and abundant food sources.

Larus delawarensis plays a role as both a scavenger and predator in its ecological niche. It feeds on a diverse diet that includes fish, insects, and human refuse, demonstrating its adaptability to different food availability. The species contributes to the ecosystem by helping control insect populations and cleaning up dead material.