The number of Adélie penguins in East Antarctica has almost doubled overnight, with previous population estimates wildly wrong.
New research from an international team from Australia, France and Japan used cameras, aerial and ground surveys estimated around 5.9 million birds across a 5000km stretch of the east coast. That's almost 3.6 million more than previously thought.
Using that figure, they estimated there were around 14 to 16 million of the birds around the world.
The birds rarely leave the Antarctic coast of sea-ice, but there are two reported cases of them as far as Marlborough and Kaikoura - one alive and one dead.
The previous estimates only took into account breeding pairs because the non-breeding birds were often at sea and hard to count, Australia Antarctic Division seabird ecologist Dr Louise Emmerson says.
"However, our study in East Antarctica has shown that non-breeding Adélie penguins may be as, or more, abundant than the breeders."
She says the extra numbers can help future-proof the species.
"These birds are an important reservoir of future breeders and estimating their numbers ensures we better understand the entire population's foraging needs," she says.
Their increased numbers mean there could possibly be more interactions with humans, with both preferring the same rocky, ice-free areas to set up camp.
There are nine permanently occupied research stations in East Antarctica with one million birds (29 percent) within 10km of a station, and 44 percent within 20km of a station.
The study also showed the birds ate 193,500 tonnes of kirll and 18,000 tonnes of fish during the breeding season just in East Antarctica.