The Collaborative International Dictionary
Swartback
Swartback \Swart"back`\, n. (Zo["o]l.) The black-backed gull ( Larus marinus); -- called also swarbie. [Prov. Eng.]
Wiktionary
swartback
n. (context UK dialect English) The black-backed gull (''Larus marinus''), or swarbie.