So they have to tranquilize the rhinos first. That in itself can kill the animal. I can't find a reference, but that reminds me of an old project to dye rhino

So they have to tranquilize the rhinos first. That in itself can kill the animal. I can't find a reference, but that reminds me of an old project to dye rhino horns pink. Sadly, a few rhinos didn't survive the process.