Scientists find close to 20% more emperor penguin colonies in Antarctica, could raise total numbers by 5-10%
The analysis reveals that most of the newly-found colonies are situated at the margins of the emperors' breeding range and thus these locations are likely to be lost as the climate warms
There are nearly 20% more emperor penguin colonies in Antarctica than was previously thought, according to scientists who used satellite mapping technology to spot the new locations. The results provide an important benchmark for monitoring the impact of environmental change on the population of this iconic bird.
The research team used images from the European Commission's Copernicus Sentinel-2 satellite mission to locate the birds. They found 11 new colonies, three of which were previously identified but never confirmed. That takes the global census to 61 colonies around the continent. According to the authors, while these extra colonies represent an increase of almost 20% in the number of breeding sites, the numbers of penguins at each site are likely to be small. They estimate that the newly-discovered locations may increase the global estimate by 5%-10%.
“This is an exciting discovery. The new satellite images of Antarctica's coastline have enabled us to find these new colonies. And while this is good news, the colonies are small and so only take the overall population count up by 5-10% to just over half a million penguins or around 265,500-278,500 breeding pairs,” writes lead author Dr Peter Fretwell, a geographer at British Antarctic Survey (BAS), in the analysis published in Remote Sensing in Ecology and Conservation.
The study found several colonies located far offshore, situated on sea ice that had formed around icebergs that had grounded in shallow water. These colonies, up to 180km offshore, are a surprising new finding in the behavior of this increasingly well-known species, according to the authors. “Our search revealed 11 colonies not identified in the latest satellite imagery inventory, two in the Peninsula Region, three in West Antarctica and the remaining six in East Antarctica. These sites included two new sites breeding on ice shelves, and two off-shore sites. The largest of the new colonies found was at Cape Gates. This colony consists of several groups of penguins and is likely to comprise many thousand pairs,” says the research team.
Emperor penguins are known to be vulnerable to loss of sea ice, their favored breeding habitat. With current projections of climate change, this habitat is likely to decline. Even under the best-case scenario with a global temperature increase of 1.5°C, the population will decrease by at least 31% over the next three generations, say researchers. Hence, regardless of the greenhouse gas emissions scenario, there is an ongoing need to monitor the population size and distribution of this species, emphasize researchers.
Since emperor penguins need sea ice to breed, they are located in areas that are very difficult to study because they are remote and often inaccessible. For the last 10 years, British Antarctic Survey scientists have been looking for new colonies by searching for their guano stains on the ice. The analysis reveals that most of the newly found colonies are situated at the margins of the emperors' breeding range and thus these locations are likely to be lost as the climate warms. They explain that comparison with recent modeling results show that the geographic locations of all the newly found colonies are in areas likely to be highly vulnerable under business-as-usual greenhouse gas emissions scenarios. The findings, therefore, suggest the possibility that an even greater proportion of the global population will be vulnerable to climate change than previously considered.
“The breeding sites are all in locations where recent model projections suggest emperors will decline. Birds in these sites are, therefore, probably the ‘canaries in the coal mine.’ We need to watch these sites carefully as climate change will affect this region,” explains Dr Phil Trathan, head of conservation biology at BAS.