The Duke and Duchess of Cambridge had to step in to protect an endangered Australian animal - from baby Prince George.
The Cambridges took their eight-month-old son to Sydney's Taronga zoo to meet a bilby - a rabbit-like marsupial - named after the royal infant.
But they had to warn keeper Paul Davies about their son's iron-like grip when he threatened to grab one of the ears of the creature, affectionately known as Australia's Easter bunny.
George clearly enjoyed his trip to the zoo and when he arrived, carried by his mother, he looked on in wonder at the crowd surrounding the enclosure and wriggled his arms and legs in excitement, squealing and gurgling when he spotted his namesake George the bilby.
His parents took it in turn to hold him in their arms and then to support him as he stood up and held on to a low clear plastic fence that surrounded the marsupial's pen.
At one point they had to grab on to their baby, who will one day be king, when he tried to climb into the enclosure to get at the bilby.
The Duchess, who wore a yellow summer dress by an independent maker, said "he's trying to grab his ear," and William added: "If he gets it he'll never let go," kissing the top of his son's head.
Mr Davies told the couple it would be fine for George to stroke the animal and went to coax the bilby closer but Kate stepped in to stop him, thinking it a bad idea, and said: "He's got quite a strong grab actually."
Zoo officials had to apply to the national Stud Book Keeper to have George, the bilby's new name, officially recognised and his old moniker Boy dropped.
Mr Davies said: "It did take me quite a while to stop calling him, 'Boy George'" and he thought the animal looked like a George and was regal too.
He added: "If you think of kings of the past he has got that worldly presence. He has very little fear of anything. He calls his own shots. He is a very confident little animal."
Greater bilbies, nocturnal marsupials who hide in burrows during the day, are rabbit-like creatures with large ears that pick up sounds of insects and have long noses to sniffs out seeds and bulbs.
They were once common in Australia's grassy woodlands but have been driven to the verge of extinction by predators such as foxes and cats and competition from rabbits, all introduced to the country by British settlers.
With only 10,000 left in the wild in northern Queensland and Western Australia, a conservation campaign begun in the late 1960s has gathered pace in the last decade with chocolate Easter bilbies replacing chocolate bunnies in many Australian children's homes.
George, dressed in blue shirt, navy shorts, socks and shoes, was carried by Kate inside the Australian Nightlife House to view other nocturnal animals, including an echidna, spinifex hopping mice and feather-tailed gliders before emerging to have a proper look at the bilby.
In bright sunshine, George and his parents were shown around the bilby enclosure by Cameron Kerr, the zoo's director and chief executive, and Mr Davies.
The baby prince watched as William and the keeper took it in turns to feed the three-year-old rabbit-like creature.
Mr Davies, a 57-year-old Briton originally from Hertford who has lived in Australia for 33 years, enticed him with a tasty dish of beef, carrot, and live, wriggling mealworms which William also fed him.
After meeting the bilby, William and Kate unveiled a plaque that read: "A national gift from the Commonwealth Government to commemorate the birth of His Royal Highness Prince George of Cambridge."
Australia's government under former prime minister Kevin Rudd gave Taronga Zoo's bilby preservation programme a £5,500 donation as a national gift to commemorate George's birth on July 22 last year.
The baby prince interrupted the zoo chief executive's speech with some enthusiastic squealing before gleefully taking a present from him, a stuffed toy bilby.
There was another gift, a yellow car sticker that said "Wild child on board," which George happily took and tried to chew. "Munch, munch, munch," said William.
His son threw the toy bilby on the floor, as he tried to chew the sticker, to the laughter of everyone watching. William, who was wearing a blue short-sleeved check shirt and navy trousers, said: "He does love it honestly".
Mr Kerr said he hoped the royal visit would help highlight efforts to conserve Australia's native animals.
He said: "Bilbies were once found right throughout Australia, but are now threatened in the wild.
"Taronga is part of a national breeding programme across a number of Australian zoos and wildlife organisations that are involved in conservation, breeding and research to provide an insurance population to safeguard this species into the future."
George was handed over to his nanny, Maria Teresa Turrion Borrallo, and taken off to the shade when the rest of the royal party went on to the tree kangaroo enclosure where William fed them avocado.
The couple, who were cheered by crowds lining their route through the zoo, also stopped to feed carrots to the giraffes before going on to view an Australian native animal show featuring a koala, a pink galah bird, and other species.
Mr Davies, the bilby keeper, cried tears of joy after meeting the couple and George and showing them around the darkened inside of the Australian Nightlife House.
He said: "Prince George, he was so lively with everything he saw. He had only a short attention span. He knew when it was time to move on but he was lovely."
"They were like any other family coming into the zoo for a day out.
"George really liked George - it was just fantastic to see him excited, brilliant.
"If you don't know what a bilby is, you do now - everybody knows - that's conservation in a nutshell, that's world recognition of a bilby."
In the native animals show William and Kate joined supporters of the zoo in an amphitheatre, sitting in the front row with their entourage behind them.
The couple smiled and laughed at each other as the birds flew inches over their heads or ran across the stage area as they played out the Aboriginal legend of how they got their colours.
As a large Brolga bird flew into the arena the compere Brendan Host, a bird trainer, told the guests: "I'd like to introduce you to Harry, you can recognise him from his red hair."
Later the royal couple ventured on to the stage to stroke some of Australia's native animals including two spiky echidnas - a form of spiky anteater - then stood up to look at a quokka, a small marsupial.
An iconic koala called Leuca was introduced to the couple and they stroked the animal held by keeper Lucinda Cveticanin, and Kate even leaned forward to give it a sniff.
Miss Cveticanin, 37, has worked at the zoo for 10 years and said: "He behaved himself beautifully. William and Kate were really keen to touch him and were surprised his fur was so thick and woolly.
"Kate leant forward to smell him and reeled back in shock. The eucalyptus comes out through their fur and she was taken aback by how strong the smell was."