Pesto the penguin is growing up. How will life change for the internet’s favorite bird?
Melbourne’s 50-pound celebrity chick is molting, revealing adult feathers beneath his iconic brown fluff. Here’s what to expect as he waddles into adulthood.
Pesto’s wearing… pants? Or at least that’s what it looks like—videos from the Sea Life aquarium in Melbourne, Australia show its world-famous giant baby king penguin Pesto waddling around with his white adult feathers emerging like a pair of shorts beneath his juvenile brown fluff.
This change has been anticipated by experts, such as Jacinda Early, an education supervisor and aquarist (an aquarium’s equivalent to zookeeper) at Sea Life who regularly leads tours of the penguin exhibit for school groups. She’s had to tailor her programming to feature Pesto more heavily after his popularity exploded online. Celebrities like Katy Perry and Olivia Rodrigo even stopped by to say hi.
But this new milestone for Pesto will be a big change. Here’s what experts say Pesto’s fans can expect as he grows into an adult penguin.
What will Pesto look like?
“Once he becomes one of the guys and he gets that regular adult coat, I think he won’t be as notable,” Early says. “He’s just going to look like everyone else.” But keen-eyed visitors will still be able to spot Pesto, this year’s sole king chick, thanks to a combination of his height—inherited from his biological father Blake, Sea Life’s oldest king at 22—and his black beak, which won’t gain its trademark orange patch until he reaches sexual maturity in about two more years.
“We never know how they’re going to fledge,” Early says. “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.”
Pesto’s wings and lower body began to go first, and Early is looking forward to when he’ll display a Winnie-the-Pooh style crop top.
Why is he losing his brown feathers?
In the wild, king penguins usually begin to fledge—a bird’s first molt, when it loses its downy plumage—around 13 months after they hatch. Pesto, born in January of this year, is a little early.
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King penguins are born in the Southern Hemisphere’s summer and autumn, and in the wild they fast during the cold austral winter. Chicks that haven’t been fed well enough by the start of winter are likely to die of starvation in the wild before their parents return to feed them in the spring. Only once feeding resumes and their body fat reserves are restored, will they have enough energy to begin fledging.
“[Fledging for chicks] can be quicker in captivity because they are exposed to more continuous food availability,” says Emiliano Trucchi, an evolutionary biologist at the Marche Polytechnic University in Italy who specializes in king penguins. Pesto got fed plentifully throughout the austral winter, thanks to the combined efforts of his adoptive parents Tango and Hudson and the Sea Life staff.
“Growing up as a penguin chick is a bit of a feast and famine scenario,” said Barbara Wienecke, a penguin expert working for the Australian Antarctic Program. “Pesto has been receiving way more food than any chick in the wild could dream of, and of course, he did not experience the long winter fast.”
Will Pesto slim down as he grows up?
Blake and Matilda, Pesto’s biological parents, were rather old to raise a chick and so the decision was made for Pesto to be adopted—something that would just as likely have happened in the wild. “If an egg spins out on the ice, a king penguin will just grab it and pop it under their brood pouch.”
His notable bulk was a combination of nature and nurture, says Early, with Blake’s heritable height combining with the availability of food to produce one big penguin.
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Pesto’s bulk wouldn’t necessarily have served him well in the wild, says Wienecke. “Penguins are naturally buoyant and body fat makes them even more so. The more fat they carry, the harder it is to go diving.” Pesto is already beginning to lose some of his bulk, thanks to the immense caloric requirements of the molting process.
“It’s very [energetically] expensive to molt,” says Trucchi. “They need to use lots of their body fat reservoir, their subcutaneous dermal layer, all of the energy they stored before, to grow new feathers. It’s a big change for the little chick.”
He expects that Pesto will rapidly slim down over the next three weeks as he works hard to grow his adult feathers as well as his adult muscles, which he’ll need both of, in order to swim and fend for himself.
Does Pesto show signs of penguin evolution?
King penguins are often mistaken for emperor penguins, but are in fact their ancestors. One million years ago, a population of king penguins headed south and began to evolve into their larger cousins, the emperor penguins. Emperor penguins are one of the hardiest, most cold-adapted animals on the planet, breeding on Antarctic sea-ice in the depths of winter darkness.
To survive, they developed defenses against the cold: their body temperature went up, they got taller and rounder, reducing their volume to surface ratio in order to lose less warmth from their body. (That’s why they can’t be effectively kept in captivity, says Wienecke. Unlike kings, who can comfortably hang out in refrigerated habitats kept between 32º and 50º F, emperor habitats would need to be expensively kept below freezing.)
“There are lots of these adaptations that had to appear at a certain point, and this could be due to what we call standing genetic variation,” Trucchi explains. “These variations could have been in the population of the ancestral king penguins, or they could be the results of new mutations appearing randomly and then getting selected for.”
Which brings up an interesting question: could Pesto’s shocking size be an evolutionary leap forward, reflecting the standing mutations that helped kings evolve into emperors millennia ago?
“Yes, could be, could be,” Trucchi muses. With an appetite like his, Pesto would certainly be suited for survival of the fittest in somewhere colder than usual.
Can we expect a Pesto Jr.?
As an adolescent penguin, and a rather tall one, Pesto will soon join the ranks of the young penguins at Sea Life, including 2022’s record hatching of six king chicks. But kings are a very egalitarian species, with no battling for dominance based on size, so Pesto’s winning personality will have to be how he eventually charms a mate.
When that hopefully happens a few years from now, there’s certainly a chance that he could pass on his genes, and Sea Life could have another big baby on their hands.
Will Pesto ever go back to the wild?
It’s not likely—although he might end up in another aquarium or zoo.
As Early explains, Melbourne’s population of kings and gentoos originates from a population taken into captivity in Edinburgh all the way back in the 1970s. Melbourne has sent its own penguins to Sydney, so if Pesto and/or his big babies are needed elsewhere, he might get to go on an adventure to start a new colony.