The Downy Woodpecker is a strange sight to see in the wild. Most the time I have spotted them, they have been upside down on a brach, or moving almost squirrel like on a tree.
This is because their food source is found in trees. They peck into the trees to find bugs and insects living in the bark.
Furthermore, the distinct sound they make when they peck against a tree actually isn't the sound of them feeding. This is actually their equivalent to a song (mating call). When they feed, their pecking doesn't produce much noise at all.
“Downy Woodpecker Overview, All About Birds, Cornell Lab of Ornithology.” Overview, All About Birds, Cornell Lab of Ornithology, www.allaboutbirds.org/guide/Downy_Woodpecker.