Sphyrapicus varius (Yellow-bellied Sapsucker) has been reported drilling sap wells in more than 250 species of trees and woody vines in eastern North America. Criteria for species selection and use of geographically restricted endemics are poorly understood. Here I report drilling frequencies in Cotinus obovatus (American Smoketree), a rare endemic whose center of abundance occurs in the wintering range of Yellow-bellied Sapsuckers in the Ozark Mountains. Horizontal bands of sap wells were present on 4.5% of specimens (DBH ≥ 7 cm; n = 402) and 12.1% of larger-diameter classes (DBH ≥ 20 cm; n = 149). Sapsuckers preferred larger trees exhibiting little cambial dieback. Latticed arrays of sap wells similar to those observed on breeding territories were present on several large specimens. This survey indicates that the Yellow-bellied Sapsucker exploits rare species that may only be encountered on their winter territories. Documentation of a yearling inspecting a preexisting array of sap wells suggests that yearlings may obtain cues for appropriate tree species selection by examining sapsucker drillings encountered on wintering grounds. Because sap wells persist for years, cultural transmission of sapping information is likely transgenerational.
