Complex sentence: Occasionally, these owls may inadvertently prey on threatened species: following the devastation to its populations from DDT, the reintroduction of the peregrine falcon was locally hampered due to predation on nestlings and adults by the great horned owl.
Split into simpler sentences: Occasionally, these owls may inadvertently prey on threatened species. Following the devastation to its populations from DDT, the reintroduction of the Peregrine Falcon was locally hampered due to predation on nestlings and adults by the Great Horned Owl.