There are many articles, some say black vultures do kill livestock sometimes and turkey vultures don't, some say the opposite.
Most say black vultures are the ones that go after livestock on occasion, and have been known to kill newborn calves, piglets and goats.
This is one on Florida vultures:
https://avibirds.com/vultures-in-florida/
We have both here, a lot of them, and I've never had a problem with my chickens. I have a large, open but fenced, run, and I've had them fly over, but never land. My roo's always alert when they fly over and my chickens take cover. On foggy mornings they often roost in dead snags or on power transmission towers in large numbers, which is pretty creepy looking.
I think, like many predators, opportunities vary, depends on how the food supply for them has been, numbers of birds, how hungry they are. I wouldn't necessarily just assume it could NEVER happen, but I don't lose sleep over it. If you have places your birds can get under cover, bushes, tarps, etc, places to hide, it will minimize the risk. I always have my chicks growing out in a covered run, either a tarp or bird netting at minimum, so they are safe from hawks also, until they are bigger. Most air born predators will not fly into or land in a place where they are not comfortable of escaping, or where the odds are against them. Just running strings across the top of a run in a random pattern can be enough to convince a flying predator not to try. I've seen some hang old CD's or DVD's also, the flash of light reflecting can help deter them.