eWestern Birds

Ranges of the Subspecies of the White-breasted Nuthatch in California

Edward R. Pandolfino, Kenneth P. Able, Jon L. Dunn, Kimball L. Garrett, and Dawn Lasprugato

ABSTRACT: There are significant discrepancies among the published descriptions of the ranges of California’s two subspecies of the White-breasted Nuthatch, Sitta carolinensis aculeata and S. c. tenuissima. To reevaluate the relationship between their ranges in the state, we recorded observations along the west edge of the range of S. c. tenuissima and the east edge of the range of S. c. aculeata, identifying birds to subspecies by diagnostic vocalizations. We made 457 observations in which the subspecies could be confirmed vocally. We found that the two subspecies are generally well separated in the north-central portions of the Sierra Nevada, with S. c. aculeata found well west of the crest and S. c. tenuissima east of the crest or at the higher elevations on the west side. The relatively wide band of dense fir (Abies spp.) and mixed conifer forest at the middle to lower elevations of the west side likely forms a barrier between them. In the southern Sierra and at the southern edge of the Cascades, the two subspecies come into close contact and we found evidence suggesting intergradation in the latter area.

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