Robert and Bindi Irwin appear on The Project

The kids of legendary crocodile hunter Steve Irwin united for a special spot on The Project on Sunday night, with co-host Robert delivering a heartfelt message of love to his “amazing” sister Bindi.

Bindi stopped by the popular news and talk show to talk up the release of her new children’s picture book book You Are A wildlife Warrior, which is set for release in February 2025.

With his sister dialling in from Australia Zoo dressed in the iconic khakis made famous by her beloved father, Robert spoke about how she had worked on the book as she struggled through endometriosis, a crippling disease that affects almost one million Australian women.

“You worked on this book in the throes of the endometriosis struggle you went through so publicly,” he said.

“You came out the other side being an advocate for endo and a continuous advocate the natural world.

“And this is a gift for the world. The younger generation, thank you for always approaching everything with such a sense of selflessness and absolute courage.

“You truly are amazing, Bindi.”

Endometriosis can devastate fertility and cause severe pain.

It occurs when body tissue that is similar to the lining of the uterus grows outside the uterus in other parts of the body, usually in the pelvis.

Bindi said her daughter Grace was an inspiration for the book.

“I started working on this just after Grace was born,” she said.

“I held this beautiful baby girl in my arms and went, ‘Oh my goodness, she’s going to have such an incredible life here at Australia Zoo running around with animals’.

“That’s where I got started right away. It’s been about three years in the making. It feels really good to be here. Grace has had a sneak peak of the book and she pretty much names all the animals in the book.”

The book takes readers through Australia Zoo, located on the Sunshine Coast in Queensland.

“I’m really thrilled to be able to share our work with wildlife and conservation with the next generation of warriors and hopefully inspire kids to love and appreciate our natural world,” she said.

Bindi said Grace loved her “uncle Robert” and she lit up “like Christmas” whenever he was around.

“She gets so excited, he’s so much fun,” she said laughing.

“Robert, I love you, you are a good brother.”

She also branded Robert “the fashionable Irwin”.

Robert wore a sharp suit and black shirt for his hosting gig.

Snake bite to the face? Not a problem for this wildlife warrior, who's becoming more and more like his father Steve Irwin every day.

Earlier in the night, he said jokingly he was wearing “khaki on the inside”.

Mum Terri was also in the audience for the ‘Irwin fest’ program, with Robert revealing the family had celebrated her 60th birthday on Saturday.

Before Bindi’s appearance, The Project reported on new research showing animals possess elements of “complex intelligence”, including deep emotions and feelings.

Robert said scientists and conservationists had only just “scratched the surface” of understanding animal intelligence.

He said the crocodiles he interacted with every day were “smart” and recognised him.

“They recognise you, they learn, they remember, they have personalities,” he said.

“The way they show it is so different. Your dog or cat comes home with their tail wagging but a croc is striking at you trying to eat you.

“Animals, 100 per cent, unequivocally have feelings, emotions and this emotional intelligence that is so deep, we’ve only just scratched the surface.”