Prince George, seven, Princess Charlotte, five, and Prince Louis, two, quizzed the 94-year-old broadcaster in a video recorded at Kensington Palace in August.
Princess Charlotte revealed she likes spiders, and Sir David told Prince Louis his favourite animal is a monkey.
Prince George, who Sir David had gifted a fossilised giant shark’s tooth to mark their meeting at Kensington Palace, asked him which animal he thinks will become extinct next.
Sir David told him:
“Well let’s hope there won’t be any, because there are a lot of things we can do when animals are in danger of extinction. We can protect them.
“About 40 years ago, I was with some mountain gorillas in the centre of Africa.
“Mountain gorillas were then very very rare, there were only 250 of them left, and we showed pictures of them on television, and people thought how terrible it would be if these became extinct.
“So they subscribed lots of money and lots of people came to help, and now there are over a thousand of them.
“So you can save an animal if you want to and put your mind to it, people around the world around the world are doing that, because animals are so precious – so let’s hope there won’t be any more that will go extinct.”
Princess Charlotte revealed she likes spiders, and asked the veteran nature commentator if he likes them too.
Sir David told her:
“I love spiders, I’m so glad you like them. I think they’re wonderful things.
“Why is it that people are so frightened of them? I think it’s because they’ve actually got eight legs, which are much more than us, and if you’ve got eight legs you can move in any direction, so you can never be quite sure which way that spider’s going to go.
“He could go this way or that way… so people don’t like them, and they don’t like their hairy legs either.
“But spiders are so clever. Have you ever watched one trying to build it’s web? That is extraordinary.
“How does it make a circular web like that attached to trees at either side or bits of vegetation? How do they do it? Try and watch and see how they do it, it’s marvellous.”
The Duke and Duchess’ youngest, Louis, asked Sir David which animal he likes best.
“I think I like monkeys best, because they’re such fun. They can jump all over the place, and they don’t bite, at least… some do, but if you’re a bit careful they don’t bite.
“And they’re so funny, and I like them a lot. Mind you, you can’t have monkeys sitting around the home because that’s not where they live, they live out in the forest.”
Sir David added that if he had to choose between getting a puppy and a kitten as a pet, he would choose a puppy.