The acorn woodpecker (Melanerpes formicivorus) is a medium-sized woodpecker, 21 cm (8.3 in) long, with an average weight of 85 g (3.0 oz). Taxonomy The acorn woodpecker is a fascinating bird that was first formally described in 1827 by the English naturalist, William John Swainson. Swainson named the species Picus formicivorus after a specimen he collected in Mexico. The … [Read more...] about Acorn woodpecker