The Pileated Woodpecker is the largest woodpecker in the United States, second to the now extinct Ivory-billed Woodpecker.  There’s no mistaking this bird; big, bold and announces his present with a very distinctive call. 
This is one of six woodpeckers in Peachtree Park if you count the Northern Flicker and Yellow-bellied Sapsucker as woodpeckers. We’re pretty sure there is at least one pair that nest here.
These birds mainly eat insects, especially carpenter ants and wood-boring beetle larvae. They also eat fruits, nuts, and berries, including poison ivy berries (hooray for them). Pileated Woodpeckers will often chip out large and roughly rectangular holes in trees while searching out insects, especially ant galleries. 
Usually, Pileated Woodpeckers excavate their large nests in the cavities of dead trees. Woodpeckers make such large holes in dead trees that the holes can cause a small tree to break in half. The roost of a Pileated Woodpecker usually has multiple entrance holes. 
A pileated woodpecker pair stays together on its territory all year round and is a non-migratory species. It will defend the territory in all seasons, but will tolerate floaters during the winter. When clashing with other Pileated Woodpeckers, they engage in much chasing, calling, striking with the wings, and jabbing with the bill. 
Drumming is most commonly done to proclaim a territory and hollow trees are often used to make the largest sound possible.  They will also drum on man-made structures that reverberate loudly such as eaves and gutters.
References and Additional Information
 Wikipedia: Pileated Woodpecker
 The Sibley Guide to Birds, second edition – David Allen Sibley
 Cornell – All About Birds: Pileated Woodpecker
 Cornell – All About Birds: Pileated Woodpecker – sounds