If global warming is causing extinction, it isn't happening to Adélie penguins in the Southern Ocean.

Adélie penguins have long been considered a key indicator species to monitor in order to understand the effects of climate change and fishing in the Southern Ocean. New evidence shows that the population is 3.79 million breeding pairs - 53 percent larger than previously estimated.  

High-resolution satellite imagery permits regular monitoring of Adélie penguins across their entire breeding range, and by extension the health of the Southern Ocean ecosystem. The authors combined that with recent ground counts and other techniques to identify Adélie Penguin colonies over the 5,500 kilometer Antarctic coastline in the lowest regions of the Antarctic Ocean, or Southern Ocean—a distance 40 percent longer than from New York to Los Angeles.

A first-ever global census of Adélie penguins shows that the population is 53 percent larger than previously estimated.  Photo Credit: Michelle LaRue, University of Minnesota

Prior to this, ecologists had claimed Adélie penguin population declines on the Antarctic Peninsula but that was in conflict with other evidence in their breeding range. The new paper seeks to put all of these scattered pieces of information into a global perspective. It shows that Adélie populations at the global scale appear to be growing. Key to identifying the colonies—including the discovery of 17 populations not known to exist—was use of satellite imagery to pinpoint the spectral characteristics of the excrement - guano - of Adélies, a way to clearly identify the species’ breeding grounds. The research has implications to better inform policy makers and scientists regarding Marine Protected Areas and climate change.

“We believe this is a landmark study with data that provides not only information on the population dynamics of Adélie penguins but injects critically needed information into the ongoing negotiations regarding the implementation of Marine Protected Areas in the Southern Ocean,” said co -author Heather Lynch, a Stony Brook University ecologist. 

"We now have an important population baseline for Adélie penguins,” said Michelle LaRue, a conservation biologist at  the University of Minnesota. “Our methods also allow for annual, regional-scale comparisons of population trends that can more precisely inform us about ecosystem health and subsequent sustainability and conservation measures."

Over the past several years, the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) has discussed the establishment of a series of Marine Protected Areas surrounding Antarctica and the sub-Antarctic islands. Lynch explained that Adélie penguins are not only themselves a species of conservation concern, but their distribution and abundance globally also reflect the distribution of their marine prey—primarily krill and fish.

“Our finding of a 53 percent increase in Adélie penguin breeding abundance compared to 20 years ago suggests that estimates of krill consumption by this species may be seriously underestimated. Leaving enough prey for natural krill predators is an important element in ensuring fisheries proceed sustainably, and for the first time we have a global map of Adélie abundance that can be used by CCAMLR,” added Lynch.

Published in The Auk, Orinthological Advances. Source: University of Minnesota.