The list in California Birds (A Checklist of the Birds of California, Calif. Birds, 1:4-28, 1970) follows Mayer and Short (Publications of the Nuttall Ornithological Club, 9:66, 1970) in suggesting that Pygmy and Brown-headed Nuthatches may be the same species. While the data presented by Norris (Univ. Calif. Publ. Zool., 56:119-300, 1958) could be interpreted this way, the two have different call notes.