The California Least Tern (Sterna antillarum browni) historically nested commonly on coastal beaches from Monterey County, California, to Cabo San Lucas, Baja California (Grinnell 1928, Grinnell and Miller 1944). However, substantial population declines were documented in the subspecies’ United States range during the years following World War II, and the population was given Federal and State endangered species status in 1969 and 1971.