Almost six million Adelie penguins are waddling along the icy Antarctic continent, 3.6 million more than previously estimated, according to a new study.
The research has implications for both terrestrial and marine conservation, with more birds potentially interacting with human activities on the continent and in the Southern Ocean than previously thought.
A team of Australian, French and Japanese scientists used aerial and ground surveys, tagging and re-sighting data, and automated camera images over several breeding seasons.
They focused on a 5,000 kilometre stretch of coastline in East Antarctica, estimating 5.9 million birds and extrapolating that out to likely global estimate of 14-16 million birds.
According to Australian Antarctic Division seabird ecologist, Dr Louise Emmerson, up until now population estimates only took into account breeding pairs and did not include non-breeding birds.
"Non-breeding birds are harder to count because they are out foraging at sea, rather than nesting in colonies on land," Emmerson said.
"However, our study in East Antarctica, has shown that non-breeding Adelie penguins may be as, or more, abundant than the breeders," said Emmerson.
"These birds are an important reservoir of future breeders and estimating their numbers ensures we better understand the entire population's foraging needs," Emmerson said.
Lead author of the study, Dr Colin Southwell, said the rocky, ice-free areas preferred by the penguins for nesting is also a region preferred for research stations due to ease of resupply.
"There are currently nine permanently occupied research stations in the ice-free areas of East Antarctica and we found over one million birds, or 29 per cent of the population, breed within 10 km of a station, and 44 per cent within 20 km of a station," Southwell said.
"Of the 16 Antarctic Specially Protected Areas in the study region, eight contain breeding Adelie penguins, encompassing about 10 per cent of the breeding age population.
"By identifying significant penguin breeding populations near stations we can better identify which areas may need enhanced protection into the future," Southwell said.
The research also estimates the amount of prey (krill and fish) needed to support the Adelie penguin population.
"An estimated 193,500 tonnes of krill and 18,800 tonnes of fish are eaten during the breeding season by Adelie penguins breeding in East Antarctica," Emmerson added.