Every year our field workers observe juvenile penguins returning to shore for their first molt. In honor of this momentous time in a penguin’s life, we are bringing to you Fat Penguins Week!
Photo credit: Kalyna Durbak
In late austral summer and early austral fall, Magellanic penguins undergo their annual catastrophic molt. For approximately 19 days, juvenile and adult penguins avoid the water and shed their old feathers (Borboroglu & Boersma, 2013). Once all of their feathers have been replaced by clean new ones, the penguins return to the ocean for their annual migration. They won’t be back to Punta Tombo until September!
Why do penguins bulk up before their molt? Penguins are forced to fast through the molting process. To prepare for the shedding of all of their feathers, penguins stop preening and oiling their feathers. The pause in feather maintenance renders their feathers water permeable – that’s not a good thing for a seabird! Since they can’t go into the ocean to forage, penguins have to fatten up in order to survive their molt.
Join us as we celebrate the fattest juvenile Magellanic penguins of Punta Tombo! Cast your vote between Feb 23 – 27 2026 on our Fat Penguin Week Page, and check back on our socials for more facts about juvenile penguins and molting.
Help us crown the champion: vote for the best fat juvenile penguin. 🐧🗳️
We’d like to thank Anna Testorf, an undergraduate Biology major at UW, for coming up with this amazing idea. We hope you enjoy participating as much as we had fun preparing it!
