I think private sanctuaries are very important. Many species like the white rhino are already extinct. The problem is finding people willing to fund private sanctuaries as more and more of the natural world becomes extinct at a faster and faster pace. The other issue would be that if the gray wolf is no longer part of the natural ecosystem (and only exists in private sanctuaries) it will affect the rest of the ecosystem:
I remember reading an article a few years ago: I think it was about for some reason people obliterating opossums. Not sure why, but they did. And many believe that is why we now have such an infestation of lyme disease and deer ticks. Just like blow-back in foreign policy, there is blow-back in nature/ecosystems when humans destroy species.
It's outside the scope of this argument, but I'm also opposed to unnecessary cruelty to any sentient live being. It's one thing to shoot a deer point blank between the eyes so its suffering is minimized. It's quite another to put traps out and have wolves, deer, and other live beings get their paws in one of these traps and linger for days and weeks in agony before they finally die. And, yes, this does happen. I think this cruelty should be outlawed by States, but if it's not, this is where I have no problem with a Federal law outlawing this kind of torture.
I do believe animals have rights. Maybe not the same rights as humans. But a right to be treated humanely.