Calypte anna, commonly known as Anna's Hummingbird, is native to the western coastal regions of North America. Its geographical distribution primarily includes areas along the Pacific Ocean ranging from southern Canada through the United States (particularly the states of California, Oregon, and Washington) and extending down into northwestern Mexico, particularly Baja California.

Anna's Hummingbird typically inhabits a variety of environments, including open wooded areas, gardens, and urban parks. It thrives in environments that provide abundant flowering plants for nectar, as well as trees and shrubs for nesting and perching. The climate in its native habitat is generally mild, with variations ranging from coastal fog zones to more arid inland areas.

Anna's Hummingbird occupies an ecological niche as a pollinator, primarily feeding on nectar from flowers, which helps in plant pollination. It is also known to consume small insects and arthropods as a source of protein. This species is highly adaptable to human-modified environments, often found in gardens and backyards where feeders are available. This adaptability, along with a lack of natural avian competitors in some regions, allows for a relatively wide ecological niche.