A small bird with a long curved bill. Adults have an obvious dark cap (black on males and gray on females) and mask with dark marks down the side of the chest. Note the white corners to the fanned tail that can be obvious in flight. Young birds are plain buff-colored underneath and plain brown above. Young birds could be confused with female Scarlet Honeyeater, but note that Scarlet Honeyeaters have a shorter bill. Eastern Spinebills are active and fast, darting around quickly between flowering trees in wetter forested areas as well as parks and gardens. Voice is a loud repetitive piping whistle.