Red-naped and Red-breasted Sapsuckers, together with the Yellow-bellied Sapsucker (Sphyrapicus varius), form a superspecies. These 3 species have, for the most part, separate distributions but were long treated as forms of a single species – the “Yellow-bellied Sapsucker” – until 1983, when systematic studies showed distinctions sufficient to warrant taxonomic treatment as separate species. The Red-breasted Sapsucker has a coastal distribution from northern British Columbia to California; wintering individuals do reach northern portions of Baja California. The biology of these 3 sapsucker species appears to be quite similar.
The name “sapsucker” has been applied to the woodpecker genus Sphyrapicus because these birds create sap wells in the bark of woody plants and feed on sap that appears there. Red-breasted Sapsuckers occupy similar areas in all seasons and usually make sap wells in conifers for most of the year. Because of this large investment in maintenance of sap wells, sapsuckers defend wells from other sapsuckers, as well as from other species.