The King Penguin is the second-largest penguin out there, second only to the very similar-looking Emperor Penguin. The King Penguin has a longer breeding cycle than the Emperors, with chicks taking almost 16 months to fully fledge and become independent of their parents. As the breeding cycle is so long, their colonies are continually occupied. Since caring for the offspring for over a year takes a massive amount of energy, the adult penguins often leave for weeks at a time to fish and replenish their fat stores enough to feed the youngsters. While their parents are out fishing, the young king penguins form crèches, watched over by just a few adult penguins, who stick close by primarily to protect the crèche from the potential-but-uncommon predators.
Imagine coming upon thousands upon thousands little wooly birds taking up a massive area of an island, with a single adult king penguin waddling around here and there. If you didn’t know about the crèches of other penguin species, why would you suspect anything besides this being a previously-unknown species? The early explorers and naturalists certainly thought as much. The early “Wooly Penguin” representations by Latham and a couple of other ornithological and antarctic naturalists have all been confirmed to have been the juvenile form of the King Penguin.
A General History of Birds, Vol X. John Latham, MD. 1781.