This sort of thing is a huge problem here in New Zealand. The only native mammal here is a bat, we have mostly birds which evolved for a really long time with only avian predators. So they’re hilariously poorly adapted for surviving standard predators (cats, rats, dogs etc) which first the Maori and subsequently Europeans brought. For example, many of them are flightless and tend to freeze when threatened - works well against eagles but is a terrible idea when threatened by a cat.
As a result, we have many animals, mostly birds, which are totally unique and also critically endangered. Many of them can only survive on offshore islands which have been comprehensively cleared of predators at vast effort and expense. The islands need to be relatively accessible since humans have to get to them to maintain them, but it turns out that once in a while a predator will swim quite vast distances for no apparent reason, and it only takes one to mess up years of painstaking work. Quite apart from killing a bunch of birds whose total remaining numbers might range from the tens to the hundreds of individuals.
As a result, we have many animals, mostly birds, which are totally unique and also critically endangered. Many of them can only survive on offshore islands which have been comprehensively cleared of predators at vast effort and expense. The islands need to be relatively accessible since humans have to get to them to maintain them, but it turns out that once in a while a predator will swim quite vast distances for no apparent reason, and it only takes one to mess up years of painstaking work. Quite apart from killing a bunch of birds whose total remaining numbers might range from the tens to the hundreds of individuals.