Attenborough's previous series, Seven Worlds One Planet, also featured the creatures but that was during winter. This time, it is their behavior in fall that is featured.

Nick Jordan, who was the director and producer of the sun episode, said filming in China had been an exciting experience.

"The theme of the episode is about how the power of the sun drives the diversity of life on earth," he said. "In China as fall approaches, resources become very scarce, so the monkeys have to battle it out for pine cones, which are a very tasty high-calorie prized seasonal delight.

"It was filmed by local camera man Jacky Poon, who was there for several weeks and caught some amazing natural behavior. Previously we've seen the monkeys in the snow but this time it's in the golden leaves. It's a beautiful and spectacular sequence; I think the audience will love it."

Filming for the series was completed just before pandemic restrictions came in, and with Attenborough being 94, he is in the high-risk category for COVID-19 so has been housebound the whole way through.

This did present the challenge of how he would record his commentary for the film sequences, as he could not travel to the studio, but he revealed they had to use some imagination for him to work from home.

"We hung duvets all around the wall of my dining room to get rid of echo, and I spoke into a microphone on the table in front of me, watching the sequences on a monitor, with the commentary being recorded by a sound recordist sitting out in the garden, and a producer at the BBC Natural History Unit in Bristol watching along and giving me feedback on my narration," he said.

"That way, we were able to record the entire commentary. We were concerned it would sound like an amateur set-up but it's indistinguishable from the professional way."