Clint Eastwood is set to appear in conservationist filmmaker Katie Cleary’s new wildlife documentary "Why On Earth," and she recently shared how he ended up on the project and what it was like working with him.

The new documentary will focus on nature, wild animals and the relationship between humans, animals and plant life.

"We're showing what's happening to elephants, rhinos in Africa, the palm oil epidemic in Indonesia and Borneo and Sumatra, and how it's affecting the orangutans," Cleary told Fox New Digital.

"Really, the connection between humans and animals and in our natural environment and in trying to spread compassion and awareness about these issues before it's too late before we lose a lot of these species."

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Eastwood, legend of the western film genre, is narrating the documentary, and Cleary says they bonded over their shared love of animals. She promised audiences will see a new side of him they haven’t seen before.

"Yeah, he's hosting it. He takes us through the whole process. He's incredible. He's a huge animal lover," Cleary explained. "So, this film really just brings out an amazing side to him that maybe a lot of people haven't seen, which is that compassionate side, especially for animals."

Cleary was able to connect with him through her friendship with his daughter Alison Eastwood, who shares her father’s love for animals. They work closely with each other and support one another’s charities, Eastwood Ranch and Peace for Animals.

Landing Eastwood as the narrator for her documentary, Cleary worked closely with him to complete the film.

"We went up, and we filmed at his ranch," Cleary said. "It was amazing just seeing his stomping grounds and, you know, just he's surrounded in nature, and he's just an amazing person. He just he has such a big heart.

"It was great to be able to sit with him. You can see how passionate he is about wildlife and his own animals."

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Aside from learning about his passion for animals, Cleary learned to be more patient since she described him as "very calm and very patient." She was inspired by his wisdom and ability to live in the moment.

The documentary took around four years to complete, two of those years consisting of filming. The last of her interviews were conducted a month before the pandemic hit.

"We traveled throughout Africa and then … we went to South Africa, Kenya. We went to Borneo, Sumatra and Indonesia. We went to Izmir, Harrison, Mexico," Cleary explained. 

"And then we went to the capital here in Sacramento to kind of show the process of how you really affect change on a state and federal level as well."

Cleary’s passion for wildlife preservation started when she was 11 years old, when she would take birds, raccoons, squirrels and possums to her local vet to rehabilitate. She says she inherited that passion from her mother.

Her passion led her to launch her own charity for wildlife preservation, Peace for Animals. 

"I started this brand almost 20 years ago, and it really started with big cat conservation. So tiger conservation, when I was really young. And so that's why we've got the peace sign with the tiger," she said. 

"I thought that that was really iconic, and I really just wanted to focus on endangered species and wildlife."

Cleary also started her own news network called World Animal News around the same time she started Peace for Animals.

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"We do breaking news every day around the world, whether it's anti-poaching, exposing the meat, dairy industry. You know, helping people also live a healthier lifestyle and adopting a more plant based diet rescued animals," she said.

One thing Cleary hopes people take away from the documentary is to approach nature with compassion and learn to connect with the planet again.

"I really think … we have so much to learn from our natural world. And if we just kind of quiet the noise and sit for a second and just listen and be in nature and, you know, animals have so much to teach us," Cleary explained. "What are we truly giving back, and what are we leaving for future generations? And to be a voice for me, to be a voice for the voiceless. And that's why that's why I'm doing it."