So you've actually seen, with your own eyes, a vulture pursuing, chasing and attacking a live animal? Or did someone find a dead calf being eaten by vultures and assume that they killed it?About vultures...
We have Turkey and Black vultures, and it is not uncommon for them to attack newborn or very young calves and lambs. They go after the soft places like eyes, navel and anus.
I never saw this behavior before I lived in WV, but here it's fairly common. I've seen cows exhausted, working to keep vultures off their calf. I'm not sure what attracts them or why they are persistent when faced with a live, angry mama cow.
Our neighbors keep a daily watch on the cows at calving time and I have seen instances where the calf is unharmed as well as live calves maimed beyond saving with vultures actively trying to get around the cow to her cslf.
While that's no proof they would harm a tortoise or a puppy, I could not say those animals are not at risk. And a live animal is not necessarily safe from predation by vultures