The buff outer remiges are the most reliable trait for separating the buff-tailed sicklebill from the only other member of the genus Eutoxeres, the white-tipped sicklebill (E. aquila), which has a more northerly distribution.
A distinctive feature of the buff-tailed sicklebill is its robust outer remiges, which serve as a reliable identifier for distinguishing it from the sole other species in the genus Eutoxeres, the white-tipped sicklebill (E. aquila), which has a more northerly range.