When in comes to walking in Big Five reserves, it's been a tricky question to me and still is.

Anyone who has been on these trails will praise the expierience and for some it's a "unique thrill".
But my concern is that we could lose some animals facing extinction (Black Rhino) in "mishaps" in the bush. And its reality, we have lost some. Not long after my first walk in Pilanesberg in the 90's, there was an incident in Pilanesberg on a walking trail. The guide and his guests came across a Black rhino cow and her calf and were surprised by them when stepping out of the thick bush. The guide was able to scare off the cow firing warning shots (but injured her), but the calf charged him and he shot it. But should the guide have let the rhino stomp him or the guests rahter than soot it

Well, he did his job and got the guests out alive (one of them with a serious head injury).
If you join a wilderness trail you have to accept the fact that sometimes these things happen. These trails envolve not only the possibility of encountering Buffalo, Elephant, Lion and Leopard, but also Rhino. It's bad enough that the last Black Rhino continue to be target of poaching, though should these endagered animals be the target of walking tourists, too?
When we go hiking in Big Five reserves, we are encroaching the animals territory and for me it's unethical to shoot an animal that is only protecting its own territory.
As serval said, a responsible guide who knows what he is doing simply won't risk getting his guests into dangerous situations and will try to avoid encounters with Black Rhino, but there are others out there who are taking guests out specifically to give them the thrill to track Rhino.
Today I believe it's much better to watch Rhino and other dangerous megafauna from a vehicle, so you don't put the animals under too much stress and you can get out of their way more easily and quickly.
Anyway I have done the walking thing again since than, but only on walks without rifles. Why not, if you are sure no animal will be shot, decide youself if you are willing to take the (low) risk to be killed or injured by Elephant, Rhino or Buffalo. Go walking, but do it without killing an animal

the chances are very high to survive and enjoy it

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