"The natural world is the greatest source of excitement of visual beauty and intellectual interest of so much that makes life worth living.
"And that's why I got involved in wildlife film-making in the first place," Sir David told the BBC.
"The natural world is the greatest source of excitement of visual beauty and intellectual interest of so much that makes life worth living.
"And that's why I got involved in wildlife film-making in the first place," Sir David told the BBC.