Pygmy Nuthatch (Sitta pygmaea) - HBW 13, p. 131

Taxonomy: Sitta pygmaea Vigors, 1839, Monterey, California, USA.
Forms a superspecies with S. pusilla; sometimes considered conspecific, but differs in e.g. plumage, vocalizations, and various aspects of biology. Together, the two are sometimes considered closely related to S. himalayensis, shared characters including white at base of tail and nape feathers. Alternatively, superspecies may represent an older invasion of North America by ancestral stock of S. canadensis, and in recent limited phylogenetic analysis of mitochondrial DNA present species emerged basally to a clade containing the “S. canadensis group”. Geographical variation slight; in particular, all Mexican races apparently very similar (chihuahuae often merged with melanotis) and taxonomic revision possibly needed. In California (SW USA), melanotis intergrades with nominate (on Howell Mt, in Napa County) and with leuconucha (in region of San Bernardino Mts). Proposed race canescens, described from Lee Canyon, in Charleston Mts (Nevada), in SW USA, considered indistinguishable from melanotis. Seven subspecies recognized.