Complex sentence: The Tawny is capable of catching smaller owls, but may itself be killed by the Eagle Owl or Northern Goshawk, and foxes are an important cause of mortality in newly fledged young.
Split into simpler sentences: The Tawny is capable of catching smaller owls, but may itself be killed by the Eagle Owl or Northern Goshawk. The foxes are an important cause of mortality in newly fledged young.