The Guardian notes an important difference between conservationists, willing to cull invasive species to preserve biodiversity, and animal rights activists:
Ultimately, however, despite sharing a passionate concern for other organisms, conservation and animal rights groups base their actions on a profoundly different philosophy. Conservationists value species; animal rights campaigners cherish the life of each individual animal.
From a Thomist perspective it is clear that the conservationists are correct. Man is the only animal who is “for his own sake,” since man alone has reason and will, and can therefore understand the good to which he is ordered. Irrational animals exist primarily for the sake of their species, through which the wisdom of the Creator is manifested. As Pope Francis put it:
Each year sees the disappearance of thousands of plant and animal species which we will never know, which our children will never see, because they have been lost for ever. The great majority become extinct for reasons related to human activity. Because of us, thousands of species will no longer give glory to God by their very existence, nor convey their message to us. We have no such right.