Melanerpes formicivorus, commonly known as the Acorn Woodpecker, is native to the Americas. Its geographical distribution includes the western United States (California, Oregon, Arizona, New Mexico), extending through Mexico, Central America, and into the northern portions of South America. It is found in countries like Colombia and Ecuador.

The Acorn Woodpecker primarily inhabits oak woodlands and mixed evergreen forests. It is commonly found in areas with a significant presence of oak trees, as these provide both food (acorns) and nesting sites. They are also found in pine-oak woodlands and riparian environments, typically at elevations ranging from near sea level to about 3,000 meters (9,800 feet). The regions they inhabit generally have a temperate to warm climate with distinct wet and dry seasons.

The Acorn Woodpecker is a diurnal bird known for its unique behavior of storing acorns in granaries, which are trees or wooden structures with numerous holes drilled to hold their food supply. This species plays an important role in the ecosystem by helping to control insect populations and dispersing oak seeds. They are social birds, living in family groups, and utilize cooperative breeding strategies. Their preference for acorns and the oak habitat signifies their role in maintaining the balance within these forest ecosystems.