Short (1971) reported three hybrid Downy [Picoides (= Dendrocopos) pubescens] × Nuttall’s (P. nuttallii) Woodpeckers—one collected at "San Francisco," California, in the 19th century, and two along the San Diego River near Lakeside and Santee, San Diego County, California, in September and October 1949. He suggested that the two species are close relatives that hybridize where they are sympatric, but that one species’ population may be sparse enough that individuals have difficulty finding conspecific mates.