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
Nicola Sturgeon will today pledge that her party will work with others to bring about "positive change" for ordinary people across the UK.
Half of teachers said the number of youngsters dealing with difficulties, such as depression, has risen compared to two years ago.
David Cameron will use a speech today to set out plans for patients to be able to access hospital services seven days a week.