The island's ecosystem is improving, notably for birds such as Antarctic prions and white-headed petrels. Their populations are growing as pest control measures are enacted. With pests eliminated, these birds can return to breed and benefit the environment. Bird guano also fertilizes the soil, encouraging plant growth.
Option D accurately summarizes the passage's main point: island life is recovering and thriving due to pest removal, benefiting birds and plants.
Option A is incorrect, stating an increase in predatory birds, which is not supported by the text.
Option B is inaccurate; the passage does not solely attribute these positive changes to this specific protection measure.
Option C is too general and fails to emphasize the crucial role of pest absence in the island's transformation.
Therefore, the correct option is (D): With pests gone, island life is now protected, leading to the recovery of diverse bird and plant species.