Complex sentence: In the region where auks live, their only seabird competition is the cormorants (which are dive-powered by their strong feet); in areas where the two groups feed on the same prey, the auks tend to feed further offshore.
Split into simpler sentences: In the region where auks live, their only seabird competition is the cormorants (which are dive-powered by their strong feet). In areas where the two groups feed on the same prey, the auks tend to feed further offshore.