Many kinds of wildlife will sample the sweet taste of tree sap when it’s easily available. Various woodpeckers will occasionally drill into bark to get access to the sap. But the four species of sapsuckers of North America are unique in their degree of specialization on this resource, regularly drilling rows of “sap wells” in trees and then returning to sip the sticky treat as it oozes out.
Three of the sapsuckers — Yellow-bellied, Red-naped, and Red-breasted — are common and widespread, collectively found from coast to coast. They are very close relatives, differing mainly in the amount of red on the head, and they were formerly lumped into one species. But the fourth, Williamson’s Sapsucker, is highly distinctive. A specialty of western mountains, it is uncommon and elusive, a prize for birders.