Any species of gull of the genus Stercorarius. Three species
   occur on the Atlantic coast. The jagers pursue other species of gulls
   and force them to disgorge their prey. The two middle tail feathers are
   usually decidedly longer than the rest. Called also boatswain, and
   marline-spike bird. The name is also applied to the skua, or Arctic
   gull (Megalestris skua).