A typical view of a nuthatch, going down a tree trunk head first. Females have a lighter grey crown. Here's some info from the Cornell birding site:"White-breasted Nuthatches are active, agile little birds with an appetite for insects and large, meaty seeds. 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."