The American Three-toed Woodpecker’s small stature is deceptive. One study of its musculature and skeleton revealed that this woodpecker can deliver especially powerful blows. It’s been suggested this is due to the evolutionary loss of the fourth toe—an unusual trait shared only by the Eurasian Three-toed and Black-backed Woodpeckers. With only three toes, these species may be able to lean farther away from the tree and thereby hit the tree harder than other woodpeckers, all of which have four toes.

https://www.allaboutbirds.org/guide/American_Three-toed_Woodpecker/overview

While we were watching this guy drill away it became clear that there must be another individual out of sight on the other side of the tree given as we heard drumming even when this male was holding still and within a few minutes a female emerged from the hidden side of the tree.

American Three-toed Woodpeckers are much more numerous in disturbed forests than in mature green forest, so look for them in bark beetle outbreaks, recently burned areas (up through about 8 years after a wildfire), and other places with dead and dying trees. 

https://www.allaboutbirds.org/guide/American_Three-toed_Woodpecker/overview

There was only a short moment when both the female and male were visible in the viewfinder together but they do make a mine pair and 4 legs with three toes each well…that’s twelve toes.