Three Adélies penguins. PHOTOGRAPH BY CRISTINA MITTERMEIER, NATIONAL GEOGRAPHIC CREATIVE
Adélies, chinstraps and gentoos are the three penguin species which call the Antarctic peninsula home. Of the three, Adélies, Pygoscelis adeliae, are the only solely Antarctic species, that require the Antarctic conditions. It is believed that Adélies have been in severe decline, mainly due to the associated pressures of climate change. Along the peninsula’s western side seas have gotten warmer, winter air temperatures have increase and ice-free seasons have lengthened. The glacier conditions are changing rapidly, concurrently so to have the Adélies prey, specifically where and when they can hunt. In addition to this, warmer climates also result in increased precipitation, leading to the potential to drown eggs and destroy. These factors strongly contribute to increasing chick mortality and with these pressures nearly every Adélie colony on the Western peninsula is in the decline.
In 2014 co-PI Heather Lynch, an Associate Professor of Ecology & Evolution at Stony Brook University, and colleague Mathew Schwaller from NASA published that could analyze satellite photos and identify guano-smeared areas. The conspicuous guano stains in existing NASA satellite imagery of the Danger islands hinted at a large number of penguins, making this nine-island archipelago, appear as a hotspot. Lynch, together with Tom Hart of Oxford University, Stephanie Jenouvrier, a seabird ecologist at WHOI and Mike Polito of LSU, next made a trip to the islands with the objective of counting the birds first-hand. The Danger islands were known to have penguins, but due to the difficulties of reaching them, study has been very limited.
Location of Danger Island archipelago, Antarctica. Photo taken from Google Earth Pro
In December 2015, they found hundreds of thousands of nesting birds nesting and began to tally their numbers. The team also used a modified commercial drone to take images of the entire island from high above. After analyzing the images using neural network software to analyze them, pixel by pixel, they would announce in a paper released early this month that this was a previously unknown "supercolony" of more than 1,500,000 Adélie Penguins. Wow! Those are quite the numbers.
"Not only do the Danger Islands hold the largest population of Adélie penguins on the Antarctic Peninsula, they also appear to have not suffered the population declines found along the western side of Antarctic Peninsula that are associated with recent climate change," says Polito. The climactic conditions on the eastern Antarctica Peninsula and specifically the Danger Islands, allows Adélies thrive. Here, sea ice lasts far longer. The winds push ice up and around the tip of the peninsula, and a slowly churning vortex of seawater pins it against land. These conditions, unlike the western peninsula, make the area far more hospitable for Adélies.
The data published by Lynch and her colleagues is already influencing the strategies of CCAMLR, the international commission responsible for conserving Antarctica’s marine life. In a statement by Mercedes Santos, an Argentine Institute scientist who helps CCAMLR design marine protected areas (MPAs), he described a proposed MPA includes an 30-kilometer buffer zone surrounding Adélie colonies, including the ones on the Danger Islands.
To access the pdf of this free publication see:
Borowicz A, McDowall P, Youngflesh C, Sayre-McCord T, Clucas G, Herman R, Forrest S, Rider M, Schwaller M, Hart T, Jenouvrier S. (2018) Multi-modal survey of Adélie penguin mega-colonies reveals the Danger Islands as a seabird hotspot. Nature Scientific Reports. doi:10.1038/s41598-018-22313-w
