Guano Samples Reveal Why Penguin Populations Fluctuated

Gentoo penguins

Researchers looked at penguin guano to see what threatened their populations

A team of researchers made an interesting discovery regarding an endangered population of penguins living in Antarctica. By analyzing ancient guano, they found out that volcanic eruptions were responsible with the near extinction of the species.

For a long time, researchers suspected that climate change was what almost drove this species to extinction. They noticed that penguins registered fluctuations in their populations over the past decades, and they decided to see what exactly is the cause for this. They developed a study which was published in the journal Nature Communications.

Using guano to look into the penguins’ past

Initially, the researchers from the British Antarctic Survey were studying the Gentoo penguins from Ardley Island, Antarctica. Then, they decided to take a look further in the past. They went to an area which contained many deposits of guano and took several samples from it for the study. This could provide them an insight of the life of penguins 7,000 years ago.

They discovered that the penguin colony from the Ardley Island suffered greatly from volcanic eruptions which occurred nearby. The volcano in question was situated on the Deception Island. Thus, it was not climate change, but the volcanic activity which influenced the penguin populations.

Researchers took the guano samples from the bottom of a lake on the Ardley Island. Although they are several thousands of years old, they still kept a prominent smell. The chemical analysis of the guano revealed that, besides the biological matter coming from the penguins, it also contained volcanic ash.

Volcanic activity, and not climate change, influenced the penguin populations

This led the researchers to several conclusions. At least three times during the 7,000-year period, the population of Gentoo penguins on the island was almost wiped out in the area. This was caused by three massive volcanic eruptions. Then, it took the penguins up to 800 years to regain their numbers and escape the threat of extinction.

The population on the Ardley Islands now numbers 5,000 specimens. It seems that it is not affected by climate change, as the guano samples showed no link between the species and environmental conditions. This guano analysis technique is quite innovative, and researchers might use it to study other animal populations and how the volcanic activity influenced them.
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