Mark Shand - the brother of the Duchess of Cornwall - was the chairman of Elephant Family, which aims to save the endangered Asian elephant from extinction in the wild.
In a statement, the charity said it had "lost the head of our family".
The statement on the charity's website reads: "Today we have lost the head of our family. Mark Shand was a true force for conservation.
"He was both a legend and inspiration and above all our great friend. We ask at this time that people’s thoughts are with his loved ones. We will miss him always."
More top news
David Beckham's 40th birthday celebrations turned into a mini Spice Girls reunion in Marrakech.
Chelsea have won the Premier League after beating Crystal Palace 1-0 at Stamford Bridge thanks to an Eden Hazard goal
Craig Charles is quitting Coronation Street after to head back into outer space with Red Dwarf, ITV has confirmed.