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.
The thicker outer remiges are the most dependable characteristic for distinguishing the buff-tailed sicklebill from its only other genus member, the white-tipped sicklebill (E. aquila), which has a more northerly distribution.