If you are talking about the Antarctic skua, then I think it's the sea lion. If not then I don't know.
Skua predators include larger seabirds such as gulls and predatory mammals like foxes. However, skua populations are primarily threatened by human activities such as habitat destruction and climate change.
An Arctic skua is a seabird of the skua family, Latin name Stercorarius parasiticus.
seagulls (native), rats,and cats (introduced). usually only the young ones. skua's are very large birds and know how to defend theirselves.
sea lions eat skua.
Brown Skua was created in 1978.
The skua bird is sometimes called a scavenger.
Larger birds will prey on small bird eggs and chicks, to feed their own young. Skua is especially keen on feeding their chicks this way.
On the continent, adult penguins have no natural predators, but chicks are vulnerable to carnivorous birds, such as Skua, that take the chicks to feed their own young. Penguins are sea birds and their natural predators are sea animals, such as seals and whales.
A skua is a big long winged ocean bird.
Fred Skua or Tern
The brown skua got its name from its color. The name comes from a Faroese word for the subspecies known in English as the great skua.
Skua find the Antarctic beaches -- where they breed -- to be a natural habitat for them.