skua; jaeger (family Stercorariidae)
General term for any bird in the skua family, including jaegers. Used in ornithological contexts.
Skuas are known for stealing prey from other seabirds.
pomarine jaeger; pomarine skua (Stercorarius pomarinus)
Specifically refers to the pomarine jaeger/skua, a particular species within the family.
One species of skua, Stercorarius pomarinus, breeds in the Arctic.