Loss of Antarctic sea ice is causing catastrophic breeding failure for emperor penguins. This is leading to predictions that over 90 percent of emperor penguin colonies will be quasi-extinct by the end of the century. This is based on current global warming trends.
The finding comes from scientists at the British Antarctic Survey. The data presented shows that no chicks have survived from four of the five known emperor penguin colonies in the central and eastern Bellingshausen Sea.
When this information is paired with satellite images that show the loss of sea ice at breeding sites, there is a global heating connection. The loss of ice presents a vulnerability to chicks that have yet to develop waterproof feathers.
Emperor penguins are dependent on stable sea ice that is firmly attached to the shore (‘land-fast’ ice) for the majority of the year – from April through to January. Once they arrive at their chosen breeding site, penguins lay eggs in Antarctic winter from May to June. Eggs hatch after 65 days, but chicks do not fledge until summer, which is between December and January.
Penguins are not agile and climbing ashore across steep coastal landforms is a difficult task. For breeding, the birds depend upon sea ice, and in a warming world there is a high probability that this will decrease. Without it, they will have little or no breeding habitat.
In terms of the disappearing sea ice, the most extreme loss has been seen in the central and eastern Bellingshausen Sea region, west of the Antarctic Peninsula where there was a 100 percent loss of sea ice in November 2022.
As of 20 August 2023 the sea ice extent was 2.2 million square kilometres lower than the 1981-2022 median (17.9 million square kilometres). The 2023 pattern has significantly surpassed the record winter low on 20 August 2022 of 17.1 million square kilometres.
This missing area is larger than the size of Greenland, or around ten times the size of the United Kingdom.
This adds to evidence about the vulnerability of emperor penguins to a warming climate. Prior to the latest research it was noted that between 2018 and 2022, 30 percent of the 62 known emperor penguin colonies in Antarctica were affected by partial or total sea ice loss.
Emperor penguins have previously responded to incidents of sea ice loss by moving to more stable sites the following year. However, scientists say that this strategy is becoming less viable as the sea ice habitat across an entire region is affected.
The five colonies of penguins studied were each discovered in the last 14 years using satellite imagery — Rothschild Island, Verdi Inlet, Smyley Island, Bryan Peninsula and Pfrogner Point. Satellites are especially useful since the brown stains of the birds’ guano stands out clearly against the stark white of ice and snow.
Each of the five colonies had been shown to return to the same location each year to breed, with only one previous instance of breeding failure at Bryan Peninsula in 2010.
The research appears in the journal Communications Earth & Environment, in a paper titled “Record low 2022 Antarctic sea ice led to catastrophic breeding failure of emperor penguins.”
