A multinational research exercise has confirmed emperor penguins are in decline in Antarctica.
But the reasons why are, as yet, unclear.
The assessment of emperor penguin (Aptenodytes forsteri) colonies from 2009-18 found a 10% decline in the adult population now estimated at 228,000.
“We’ve seen fewer birds in 2018 than we did in 2009 but we really don’t have the ability yet to say why that is,” says Michelle LaRue, the wildlife ecologist from the University of Canterbury (NZ) and Minnesota University (US) who led the study.
The decade’s worth of shifting habitation patterns by the iconic species was studied by 23 leading scientists from 7 nations.
The sophisticated study used high-quality aerial and satellite imagery of all known colonies as part of a series of models that analyse emperor penguin population processes across the continent.
“Remote sensing has given us the context that, sometimes, these birds hop up on ice shelves or glaciers – we didn’t know they did that prior to seeing them doing that on satellite imagery,” LaRue tells Cosmos.
“On the other hand, knowing what they’re doing and where they’re going, and how often they’re feeding their chicks is something you can see when you are there on the ground.
“What’s fantastic about this work is that we were able to combine all of that information with researchers from across several different countries with lots of different experiences.”
Even then, LaRue says more data is required to begin understanding the long-term trajectory of emperor penguins on the continent.
A mixed bag for Antarctica’s most famous inhabitants
The team says half the colonies studied were likely to have seen declines in their numbers; the other half were likely stable.
Last year, several colonies of emperor penguins near the Bellinghausen Sea were subject to a “catastrophic” breeding failure due to rapid sea ice decline. But then, recently, the same group from the British Antarctic Survey, found 4 new colonies.
Adaptation is possible though. Last year, LaRue and associates from the Australian Antarctic Partnership Program and Sorbonne University in France, found some populations may respond better to changing environmental conditions, such as diminished landfast sea ice volume.
Landfast ice is fixed to the Antarctic mainland, as distinct from free-floating sea ice, which forms from frozen seawater.
Climate change is consistently cited as a primary threat to emperor penguins, with current rates of atmospheric warming expected to increase environmental pressure on these and other Antarctic species by century’s end. But LaRue is hopeful that catastrophic declines might be based on local factors, at least in the short term.
“If they’re responding to an environmental change, I don’t think it’s broad across the entire continent, I think that the different colonies are going to be doing things differently,” LaRue says.
“These are really resilient seabirds… emperor penguins live in this really, really extreme environment and they’re very well adapted for extreme situations.
“For me, when I see an extreme situation like we saw in the Bellingshausen Sea in 2022, I think it was definitely eye-opening.
“But I do think that those types of extreme scenarios are fairly localised, and that’s what I’ve seen, in my experience.”
