It's nearly 13 years since she lost her dad, but even now Bindi Irwin can't predict when the grief will sneak up on her. The last time was a couple of weeks ago as she was helping out with the crocodile show, her late father Steve Irwin's signature act at Australia Zoo.
"It was just an ordinary day and we were playing the video where we petition against harvesting of crocodile eggs," she recalls, her trademark smile fading from her face. "There's old footage of Dad with the crocodiles and, even though I've seen the video maybe 50 times, that day I started crying."
Normally pride and the sense of purpose she feels in continuing her dad's legacy carry her through the difficult moments, but occasionally the pain hits hard, demanding to be felt.
"Some days you feel the grief more than others," she says softly. "What gets to me are those moments when I'd love him to be here to share what we're doing. It could be when my brother is receiving an accolade for his photography, or it might be at the end of the day when we're having dinner and laughing. I'll think: 'I wish Dad was here for this.' But he's just not there."
If the reliably bubbly Irwin is feeling more reflective than usual, it's no surprise. This week she celebrates her 21st birthday, a milestone that seems inconceivable to those who still think of her as the enthusiastic little girl dangling jaw-length from a crocodile or toddling knee-high to a kangaroo.
She's still pint-sized – even after swapping her mud-encrusted boots for diamanté heels – and sweetly exuberant, but it's clearly a young woman with a message and no longer a girl in a treehouse who sits down with Stellar to mark the occasion.
For someone about to turn 21, her list of achievements is so comprehensive it reads more like a retiree celebrating the end of a career rather than a freshly minted adult embarking on one. Conservationist, actor, TV host, wildlife warrior, singer, dancer, author and now women's empowerment campaigner, Irwin has proven herself to be as passionate, dynamic and hard-working as her late father.
Some may have worried that Steve had set an impossible expectation for his children, emotionally declaring before his unexpected death that his "ultimate goal" and "proudest moment" would be seeing them take over his wildlife mission. What if Bindi, eight, or Robert, just two when Steve was killed by a stingray's barb, wanted to do something else?
Irwin laughs: "I'm living the dream! How many young people start their day watching a giraffe being born and end the day bottle-feeding a joey kangaroo? I don't know how I'd cope if I was living in suburbia with a goldfish. I care about the planet and my destiny is to make a difference. We're doing it our own way, but you can feel Dad's spirit in everything we do. I've found such comfort in being able to follow in his footsteps."
If her father sketched a vision, Irwin is increasingly colouring it from her own palette. She works alongside her mother, Terri, running Australia Zoo, is filming the second series of Crikey! It's The Irwins for Animal Planet, works on global conservation projects through Wildlife Warriors and campaigns extensively to encourage the Queensland government to overturn legislation that permits the harvesting of wild crocodile eggs. This year, she's branched out even further, hosting the inaugural International Women's Day brunch at Australia Zoo and launching both a new clothing range and a special tea in collaboration with Tea Tonic.
So is there a budding feminist emerging from the khaki?
"As I get older I'm more and more passionate about inspiring young women to stand up in roles which were traditionally more male dominated – such as working with reptiles," she tells Stellar. "It can be kinda scary standing up for what you believe in, especially with social media because the world is extremely critical, but we have to find the strength to stay true to what we believe in and forge ahead."
Australia Zoo prides itself on its equal pay policies, staff ratio of 65 per cent women, and being a breastfeeding accredited workplace. Irwin's dad remains her touchstone, but it's her mum who's galvanising her increasing focus on women's empowerment. Terri has been alongside her as she's evolved from the tiny eight-year-old speaking eloquently to a packed audience about her dad, to the young woman she is today. Indeed, it is Terri who, throughout her Stellar cover shoot, encourages her daughter to be bolder and more assertive. "The look we're going for is Jennifer Hawkins meets Little House On The Prairie," she jokes, much to her daughter's amusement.
"My mum is Wonder Woman," says Irwin, laughing. "She's like Sarah Connor in The Terminator. As I've grown older, I've been given this gift of perspective where I've been able to see how much she's done and I want to be there to back her up in any way I can. I would love to have even half the amount of strength she has. She has the ability to be everyone's mum, but also an extraordinary leader. We're so close and she's also my best friend."
As her firstborn poses for the cameras dressed in siren red and sparkly heels in front of the rhino enclosure, Terri acknowledges that as her daughter approaches 21, she is the embodiment of her dad. "She is surprisingly more like Steve," Terri tells Stellar. "She is a sweet lovely person with a deep soul and a great capacity for empathy. When it really matters, she will stand up for something. I've seen her do something I couldn't do in a situation where it was really important. She's a force to be reckoned with."
It's no surprise that Irwin has again followed her dad in her choice of life partner. While she's revealing no plans of an imminent engagement to her boyfriend Chandler Powell, Irwin regards the 22-year-old American wakeboarder as her partner for life. She recently posted a picture of them together on Instagram, signing it off "Always".
"Yes, he is my 'always'," she enthuses. "He's so kind and solid and always there for me. I think it's really rare to find that so early in life. My mum and dad always described their marriage as feeling like a special pair of old shoes – knowing you can always depend on someone. I know it's the same with Chandler. At the end of the day, when I'm exhausted, he will be there even if I don't have make-up on or my hair is crazy and I've been wearing the same shirt for three days."
Having met when Irwin gave Powell a tour of the zoo back in 2013, the American now works alongside the Irwins – he and Robert are great mates – and Bindi appears to have chosen someone willing to share the domestic load.
"At the moment I'm writing a book marking 50 years of Australia Zoo so I've barely said two words to Chandler over the last few weeks," she reveals. "But through it all he just lets me work and subtly does little things for me. I'll be writing and suddenly there will be a cup of tea next to me, or he'll bring a blanket or set up a picnic outside so I can enjoy a break. He does the laundry and the dishes and cleans the house."
Crucially, he makes sure she gets her animal fix, feeding meat to the kookaburras outside so they'll squawk and force her to look up from her screen. "He knows what I need. I'm extremely lucky," she says with a smile.
Irwin wants children – not, as you'd expect, because of her nurturing instincts with animals but because of her love for her little brother, 15-year-old Robert. Because he's almost six years younger, she says she's watched him grow up. "Helping him become the person he is today makes me want to become a mum. I've watched him grow and change and become his own person – he's so strong and science-minded, yet he's also quite fashionable – I think that's what we say these days."
She says Robert knows what he wants and constantly encourages her to move outside her comfort zone. "He wears linens and blue glasses and he's very fancy, whereas I walk into a shopping store place and I'm in plaid and boots. When Chandler and I walk into a room, Robert says: 'Here come the vanillas.'"
In fact, despite having her own TV show, Bindi, The Jungle Girl, winning a Logie Award, starring in films including Return To Nim's Island and Free Willy: Escape From Pirate's Cove, Irwin recently deduced she was an introvert. Her brother was appearing on an American chat show where renowned psychologist Susan Cain was listing the qualities of an introvert and Irwin realised she was not the extrovert she'd believed herself to be. "Everyone thinks I'm an extrovert because of what I do and where I live, but my favourite day would be quiet with no people, just animals."
As she rings in her 21st birthday on July 24, Irwin's most overlooked achievement may be her deeply intact sense of self. She has garnered 2.4 million Instagram followers, a global TV audience and respect on the conservation stage by being exactly who she wants to be: a young woman with a goal. As a teenager she was an antidote to the likes of Paris Hilton and the Kardashians, but now as she gallops into adulthood with a look she laughingly describes as "part glamorous, part Amish" she is more popular than ever. Clearly, it's not just because she's the figurehead for one of the nation's most iconic families, but because she's a woman of her own making. For young women crippled by body-image issues and so often sullied by cynicism, she offers a positive and outward-looking alternative. Yet she's still relatable, swooning over Grace Kelly's elegance – "I should have been born in the 1950s" – and making self-deprecating comments about her earlobes to the Stellar team.
Mostly, though, she's simply grateful: "I'm so privileged to have this platform. One of my messages is to encourage everyone to be a little more kinder."
For Terri, who would have loved more kids had Steve's life not been cut short, it's her daughter's goodness she admires most. "I've been very, very fortunate to have kids who can see outside their own bubble," she says.
Perhaps it was Terri's daily insistence that her children reflect on what they felt good about, what they were looking forward to and what deed they had done for others that has ensured her offspring are grounded.
Or perhaps it was the constant focus, not on themselves, but a wider picture. This coming Wednesday, like every year, Bindi's birthday will be spent at the zoo where visitors gain free entry for their kids to mark her special day. She doesn't mind spending her day giving tours and sharing her birthday cake with the public. As she says: "It's a great opportunity for large families with six kids to come and enjoy the animals."
The evening will be family time. They'll gather round the dining table and chat about the one gift she really looks forward to each year – the Irwins's month-long visit to the Steve Irwin Wildlife Reserve where they camp and catch crocodiles. This year, she suspects her dad's absence may be felt even more than most.
"Sometimes I wish I could ask him a question: 'How would you do this?' or 'What do you think about this?'" she muses. "He was an incredible sounding board and incredibly wise. I miss that."