This woodpecker creates shallow holes (sap wells) in the bark of trees and feeds on sap that flows into them. Like other sapsuckers, the Yellow-bellied Sapsucker creates elaborate systems of such sap wells and maintains them daily to ensure sap production, defending the wells from other birds, including other sapsuckers. When feeding young, sapsuckers usually forage for arthropods, especially ants, but some of these prey items are dipped in sap wells, perhaps for added nutritional value. In addition to drilling sap wells in trees, sapsuckers excavate nest cavities that often provide nesting or roost sites for other species of birds and even some mammals that cannot excavate their own.
The taxonomic complex comprising the Yellow-bellied, Red-naped (Sphyrapicus nuchalis) and Red-breasted (S. ruber) sapsuckers formerly was classified as a single species with an east-west pattern of increasing amounts of red plumage. Yellow-bellied Sapsucker, which shows the least amount of red, breeds east of the Rocky Mountains; Red-naped Sapsucker breeds in the Rocky Mountain-Great Basin region; and Red-breasted Sapsucker, with the head entirely red, is found along the Pacific Coast. These three species are undoubtedly similar in their biology.