Calidris minutilla, commonly known as the Least Sandpiper, is native to North America. Its geographical distribution includes areas across the United States and Canada, primarily in the boreal and temperate zones. They breed in northern regions such as Alaska, Canada, and the northern United States, and migrate to Central America and Northern South America for the winter.

The typical habitat of the Least Sandpiper includes wet meadows, salt marshes, mudflats, and shorelines. During the breeding season, they inhabit tundra and boreal forest regions where there are wet and grassy areas with abundant insect life. In winter, they are often found in coastal areas with mudflats and sandy beaches, as well as inland wetlands.

The ecological niche of Calidris minutilla involves foraging for small invertebrates such as insects, crustaceans, and mollusks found in wetland areas. Their slender bills are adapted for probing mud and sand for food. They play a role in controlling insect populations and serve as prey for larger birds of prey.