The Green Heron breeds throughout eastern North America and along the Pacific Coast from southern British Columbia through Baja California and Mexico. This species is a year-round resident along the California coast through Baja California and western Mexico and along the southeastern coast of the U.S. and throughout Florida (Davis and Kushlan 1994). The Green Heron is an accidental spring and fall migrant in Montana (Montana Bird Distribution Committee 2012).
For a comprehensive review of the conservation status, habitat use, and ecology of this and other Montana bird species, please see Marks et al. 2016, Birds of Montana.