Complex sentence: Predation of cave-nesting petrels in the Balearics by Yellow-legged Gulls is restricted to relatively few individual gulls specialising in this prey item; this means that the problems can be controlled by selective culling and the provision of plastic nest boxes.
Split into simpler sentences: Predation of cave-nesting petrels in the Balearics by Yellow-legged Gulls is restricted to relatively few individual gulls specialising in this prey item. This means that the problems can be controlled by selective culling and the provision of plastic nest boxes.