These are real birds, called Brown Creepers. They are wee little guys, and I am guessing that they got their name because of the way they creep straight up, straight down, sideways, upside-down, and otherwise over tree trunks and branches.
My huband loves to see them when we go into the woods so I drew him a brown creeper, creepin' on him.
Note: Their eyes aren't quite this large or light in color, in real life. I took liberty with the 'creep' part.
4" x 6" Ink and watercolor.