Pesto is starting to shed his brown baby fluff and grow his adult feathers.
Sea Life Melbourne Aquarium
They grow up so fast: Pesto, the viral juvenile king penguin at Sea Life Melbourne Aquarium in Australia, is starting to lose his baby feathers.
The beloved bird—who became a global internet sensation earlier this year—is beginning to molt. The brown fluff covering his body is falling off, and his black and white adult feathers are starting to grow in.
In a recent video shared by the aquarium, Pesto can be seen waddling around in his enclosure as usual. But his once-puffy appearance now looks a bit different: The top of his body is still covered in brown fluff, but his lower body is sporting sleek white plumage. As keen online observers noted, it looks like he’s wearing shorts.
“We never know how they’re going to fledge,” says Jacinta Early, an aquarist at Sea Life Melbourne Aquarium, to National Geographic’s Allegra Rosenberg. “Sometimes it looks like they’re just wearing a fur vest. Other times, it looks like they’ve got a big mohawk going down their entire body. It’s really funny and random.”
The full process will take about three to four weeks, with caretakers expecting Pesto to lose all of his youthful down by sometime in November.
Though his feathers are changing now, Pesto’s beak will remain pure black for the next two years, until he hits sexual maturity. Then, he’ll get elongated orange spots on either side of his bottom beak, a characteristic of adults.
Pesto was born in late January, which makes him about 9 months old. His birth was a big deal for the aquarium, which didn’t have any king penguin chicks hatch in 2023. He was also the only king penguin to hatch in 2024.
When he was born, Pesto weighed less than half a pound. But as he got older, he began to rapidly balloon in size, eventually tipping the scales at 50 pounds. For comparison, adult king penguins usually weigh between 31 and 37 pounds. Pesto is the biggest chick Sea Life Melbourne has ever had.
The aquarium put Pesto on public display in April. But it wasn’t until staffers held a gender reveal party in September that the massive baby bird became a worldwide celebrity.
Pesto is being raised by a pair of adoptive parents named Tango and Hudson, since his biological father, Blake, is the oldest penguin at the aquarium and likely too tired to raise a chick. But Blake is also the aquarium’s largest fully grown penguin, and his genetics can partially explain Pesto’s gargantuan size. Plus, the enormous baby has a healthy appetite, feasting on 25 fish—sand whiting, rainbow trout and salmon—each day.
As Pesto grows up, caretakers expect him to slim down. He’ll always be tall like his dad, but Pesto will likely weigh closer to 33 pounds in adulthood.
Molting is a big reason why king penguins lose weight as they mature. The process of shedding old feathers and growing new ones requires a lot of energy, so the birds deplete some of the fat stored beneath their skin.
King penguins usually molt when they are between 10 and 12 months old. Pesto’s timeline is a little accelerated, likely because of the abundance of food available to him in captivity, per National Geographic.
In the wild, king penguin chicks typically only molt after their parents return in the spring to feed them. The chicks spend the winter fasting, so these spring feedings give them a much-needed calorie boost and allow them to build up the fat stores they need for the energy-intensive metamorphosis.
Once they get their adult feathers, king penguins are much better protected against the harsh sub-Antarctic elements. Mature king penguins have four total layers of feathers—three downy inner layers, topped by an oily waterproof outer layer.
These adaptations are less important in captivity, where enclosures are climate controlled. But his new set of waterproof feathers will mean Pesto can finally go swimming with his many penguin friends and admirers.
“His best friend is his dad Hudson,” according to an FAQ page set up by the aquarium. “Aunty Queenie also loves babysitting. Other young birds such as Honey and Sausage are very fascinated with Pesto.”
Even though he’s entering his awkward teenage phase, Pesto’s popularity has never wavered. Celebrities like Katy Perry and Olivia Rodrigo have stopped by to meet the internet star in real life. Melbourne street artist Lukas Kasper also painted a massive Pesto mural in the city.
Hordes of non-celebrities have been visiting Pesto, too, including Millie Jacoby, a 25-year-old who had already come to see him twice by late September.
“We walked in and there was just this big, fluffy penguin… and we just kind of fell in love,” Jacoby tells BBC News’ Tiffanie Turnbull. “He deserves to be famous.”
