The Anna’s Hummingbird has spread north along the West Coast of North America since the mid-20th century, and Zimmerman (1973) provided a useful overview of a principal period of this expansion.In his survey of published and unpublished records, Zimmerman noted that the first reports for Oregon were in 1964, in the Rogue Valley. He also stated that there was "evidently little or no range extension [north of California] between 1940 and 1960."