The largest king penguin colony globally is on the Pigs Islands on the Crozet sub-Antarctic archipelago. But now it has lost a big percentage2 of its population.
Aerial photographs of the Île aux Cochons have worried the world. The island is better known as The Island of Pigs. It houses thousands and thousands of penguins. But it shows that half a million pairs of king penguins and their chicks have disappeared.
In early 2017, researcher Henri Weimerskirch was sent to take photos of this area. He was greatly surprised to discover that the colony had lost 88% of its population. This constitutes a third of the population of the king penguins worldwide.
Specialists reported that previously 2 million birds lived on this island. However, now only 60.000 couples who are capable of reproduction have survived. Compared to the 1980s, the number of penguins capable of breeding was 500.000. And now they only number more than half, and many are not reproducing.
This situation worried the scientific community of the Center for Biological Studies of Chizé in France. They decided to do an in situ exploration to investigate what had happened. They wanted to follow the king penguin pairs and their chicks closely.
WHAT DID SCIENTISTS DO?
The team of Henri Weimerskirch decided to devise an expedition to collect samples in situ. In November 2019, they arrived at the island of pigs in the middle of the king penguin nesting season. There they were welcomed by thousands of chicks. But they also came across large areas of rock where thousands of birds had once flocked. Now they were no longer to be seen.
Parents share tasks during the long breeding season. They share the hatching of the eggs and raising their chicks. Besides, they take turns getting food. They differ from jumping into the sea to fish. These trips can cover up to 500 kilometers or more.
Specialists placed locators on ten penguins. They wanted to see if the change in diet. Could this be the explanation for the incredible disappearance of the numbers on the Island of Pigs? That they did not find food nearby – was that the explanation? Night vision cameras were also installed to see if the number of chick predators had grown. Finally, they collected feathers and unearthed bones. They were looking for possible causes of the disappearance of diseases, for example.
Thanks to these actions, the researchers have ruled out some reasons. For example, the predators don’t seem to have had anything to do with it since the bones found have no signs of bites. Nor did the cameras record significant attacks.
WHY DID THE KING PENGUINS DISAPPEAR?
One of the hypotheses that have been discarded thanks to this experiment is that they have moved to a nearby island. When counting, there were only 17.000 pairs. This was not enough to explain the massive fall of the main group of the Island of the Pigs.
The researchers concluded that the disease did not seem to cause either. They only saw a few birds with any recent pathology or carcasses. However, the team suspects that perhaps the answer lies elsewhere. The answer could be found in the changes in the increasingly hot ocean. This could have pushed them to search for food hundreds of kilometers away. And this would increase the danger “on the road.” This also means that their young are more exposed to predators or to hunger. If the rise in water temperatures is the reason, the problem is more likely to get worse, as the scientists conclude.
This study has revealed a very strong indicator. Some of these animals did not go south as it was expected because there was more food. Instead, they went to the north. Normally, there would be less food due to the condition of the waters. This may indicate that hunting is thriving in this area, a worrying symptom of warming waters.
However, the exact reasons for the disappearance of the penguins on Isla de Los Cerdos are still unknown.