Largest king penguin colony has shrunk nearly 90%

July 30, 2018

Known since the 1960s, the colony of king penguins (Aptenodytes patagonicus) on Île aux Cochons, in the southern Indian Ocean, had the distinction of being the world's biggest colony of king penguins and second biggest colony of all penguins. However, due to its isolation and inaccessibility, no new estimates of its size were made over the past decades.

The Chizé team used high-resolution satellite images to measure changes in the size of the colony since the island was last visited by a crew of scientists (1982). At the time, the colony included 500,000 breeding pairs and consisted of over two million penguins. To calculate the area occupied by the colony at different times between 1960 and the present, the researchers studied changes in its contours over the years. They found that the colony has shrunk, yielding its territory to encroaching vegetation. Photographs taken from a helicopter during the Antarctic Circumpolar Expedition confirm that the colony's penguin population has plummeted.

Data show that the decline began in the late 1990s, coinciding with a major climatic event in the Southern Ocean related to El Niño. This event temporarily affected the foraging capacities of another colony 100 km from Île aux Cochons, causing it to dwindle. The same process may be responsible for the fate of the Île aux Cochons colony. Its size may also subject it to density-dependent effects. That is, the larger the population, the fiercer the competition between individuals, slowing the growth of all members of the group. The repercussions of lack of food are thus amplified and can trigger an unprecedented rapid and drastic drop in numbers, especially following a climatic event like the one at the end of the 1990s.

Disease is another hypothesis entertained. Avian cholera is currently ravaging populations of seabirds on other islands in the Indian Ocean, like the albatross of Île Amsterdam and the penguins of Marion Island.

Still, none of these possibilities seems to offer a satisfactory explanation for a decline of the magnitude observed on Île aux Cochons. Field studies led by CNRS researchers, with support from the French Polar Institute (IPEV), and in close partnership with TAAF nature reserve staff, should be getting under way shortly to verify initial conclusions drawn from the satellite images.
-end-


CNRS

Related Penguins Articles from Brightsurf:

Gentoo penguins are four species, not one, say scientists
First analysis combining genetic and physical differences of populations of gentoo penguins indicates they should be treated as four separate species.

Penguins are Aussies. Or are they Kiwis?
UC Berkeley and Pontifical Catholic University of Chile researchers sequenced the genomes of all 18 recognized species of penguin to assemble a family tree, showing that the largest of the penguins - king and emperor - split off from all other penguins not long after penguins arose 22 million years ago in Australia and New Zealand.

New Zealand's ancient monster penguins had northern hemisphere doppelgangers
New Zealand's monster penguins that lived 62 million years ago had doppelgangers in Japan, the USA and Canada, a study published today in the Journal of Zoological Systematics and Evolutionary Research has found.

Antarctic penguins happier with less sea ice
Researchers have been surprised to find that Adélie penguins in Antarctica prefer reduced sea-ice conditions, not just a little bit, but a lot.

Researchers go cuckoo: Antarctic penguins release an extreme amount of laughing gas
In a new study, researchers from the University of Copenhagen have demonstrated that penguins in Antarctica emit copious amounts of nitrous oxide via their feces.

Climate change and human activities threatens picky penguins
Eating a krill-only diet has made one variety of Antarctic penguin especially susceptible to the impacts of climate change, according to new research involving the University of Saskatchewan (USask) which sheds new light on why some penguins are winners and others losers in their rapidly changing ecosystem.

Whaling and climate change led to 100 years of feast or famine for Antarctic penguins
New research reveals how penguins have dealt with more than a century of human impacts in Antarctica and why some species are winners or losers in this rapidly changing ecosystem.

Researchers study chickens, ostriches, penguins to learn how flight feathers evolved
If you took a careful look at the feathers on a chicken, you'd find many different forms within the same bird -- even within a single feather.

What future do emperor penguins face?
Emperor penguins establish their colonies on sea ice under extremely specific conditions.

New sphenisciform fossil further resolves bauplan of extinct giant penguins
New Zealand is a key area for understanding the diversity of the extinct penguins and has even revealed the existence of 'giant' penguin species (larger than living penguins).

Read More: Penguins News and Penguins Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.