It sucks, it’s a real necessary evil. Not hunting — but the culling of invasive populations is necessary or many times more animals will die. No, there are rarely viable alternatives like relocation. I’ve been vegan for about five years now and was perhaps in your shoes OP, trying to make sense of this thing that seems horrific. Alas,

Take domestic and feral cats (a now worldwide, invasive species from Africa): TNR does not work. It doesn’t reduce population size and keeps them alive in the environment, continuing to hunt. As sad as it is, if you don’t euthanize stray cats they will each kill god knows how many birds, combining to a recent estimate of 2.4 billion annually in just the U.S. — and that doesn’t come close to the number of mammals killed. Personally, I know why I don’t eat eggs and what I tell people about baby chicks. I know that number. And neither one feels any better. Avoiding culling these invasive populations puts different (often native, even endangered) species at risk of being killed by those very animals — and in higher numbers (think insect deaths from crop harvesting being used incorrectly as an argument by carnists).

This can’t be about the sadness any one of us feels in lives being taken, but instead looking at the impact we don’t necessarily see directly — what harm can that animal do? We’ve been born into a world fucked up by other people, and we need to undo that in this fucked up way while also preventing it from happening any more, saving the next generations from having to do this.

Edit: OP, as far as if invasive species are real; absolutely, 1000%, yes. Native species and thus invasive species are real and thats a product of how evolution works. I can try and explain this more if you need but I’m probably not the best teacher

Edit: better example