@Paolo - Maybe you have the answer. Boswell has some very impressive tusks - how far away from Mana pools does he roam. As far as I know, elephant hunting is still allowed in Zimbabwe - some moron with a lot of money might kill him, if he wanderers into a hunting concession.
My feeling is that Boswell and several other bulls are quite territorial, and do not roam that much compared to other elephants in other protected areas (there is plenty of food and water on the floodpkain and the immediate interior, so no real need to cover vast distances), but Mana Pools is not really a big park, and Boswell could indeed stray into a nearby hunting concession, like Nyakasanga.
There are rumours that another well known Mana bull, "Big Vic" or "Curly" (which donated me some great memories on several occasions) was hunted around August 2016. As you say, elephant hunting is perfectly legal in Zimbabwe, and some hunts are organized by the same Zimparks (Zimparks has a PH to this effect - how those hunts are marketed or through which channels are sold I do not know).
The main reason why Boswell was collared was to prevent him from being hunted - I am not sure in point of law whether collaring an elephant makes it legally "un-huntable" or it is just a moral persuasion factor which comes with making official the iconic status of a certain specimen. I have heard different versions, and I guess that the answer depends on the administrative status of the land where the elephant happens to be. Craig participated to the collaring of Boswell, as documented in "The Last Great Tuskers" (and to the following softening of the collar) and told me that the Park management was adamant that either Boswell was collared or he might soon be gone. So I guess that the collaring must indeed have a protecting effect for Boswell.
Edited by Paolo, 20 March 2017 - 08:25 PM.