The Upside Down Percher by Debra Martz The White-breasted Nuthatch is famous for perching upside-down on tree trunks. They are agile little birds and quick at moving up, down and around the trees.
"They get their common name from their habit of jamming large nuts and acorns into tree bark, then whacking them with their sharp bill to “hatch” out the seed from the inside. White-breasted Nuthatches may be small but their voices are loud, and often their insistent nasal yammering will lead you right to them." Info from All About Birds