Fatherhood has made Prince William more determined to "stand up for what is very vulnerable and needs protecting".
The 31-year-old spoke of his affinity with wildlife during an informal chat filmed at Kensington Palace, which will be shown on ITV and CNN on Sunday and Monday respectively.
The wildlife is incredibly vulnerable and I feel a real protective instinct, more so now that I am a father, which is why I get emotional about it... you want to stand up for what is very vulnerable and needs protecting.
Elephants, rhinos and many other animals that are persecuted don't have a voice...
It's just so powerful. You'd think something that big and that's been around so long, would have worked out a way to avoid being caught and persecuted, but they really don't. I do feel anger, but I also feel really great hope that we will overcome this as a human race.
More top news
The Duke of Cambridge has condemned the "violent and apparently targeted murder" of the head of a wildlife conservation foundation.
Experts are warning that millions of middle-aged people are putting their health at risk due to a severe lack of exercise.
Teenagers across Wales, Northern Ireland and England are to get their results, with much of the focus on the effect of reforms in England.