adj. (Zool.) Having the outer tail feathers longer than the median ones; swallow-tailed; - said of many birds. Fork-tailed flycatcher (Zool.), a tropical American flycatcher
- Fork-tailed gull (Zool.), a gull of the genus Xema, of two species, esp. X. Sabinii of the Arctic Ocean.
- Fork-tailed kite (Zool.), a graceful American kite (Elanoides forficatus); - called also swallow-tailed kite.