Penguins have been pooping on Ardley Island off the coast of the Antarctic Peninsula for a long, long time. The population there is one of the biggest and oldest Gentoo penguin (Pygoscelis papua) colonies. But evidence from ancient excrement suggests that these animals didn’t always flourish.
The Gentoo colony on Ardley Island continues to grow in comparison to other Antarctic penguin species, which have suffered from changes in sea ice extent in other locations. A team of researchers set out to see how the Ardley population responded to past changes in climate to better inform future conservation efforts. They studied the geochemical make-up of lake sediment samples and identified elements from guano or penguin poop. Knowing the fraction of guano in lake sludge over time let the researchers track penguin population changes.
The Gentoo penguin colony peaked five times in the last 8,500 years. But rather than lining up with changes in temperature or sea ice levels, population dips corresponded to volcanic ash preserved in the geologic record. Big eruptions of a volcano on nearby Deception Island appear to have almost wiped out the colony three times over the 6,700 years that penguins have occupied the island. Each time, the colony took 400 to 800 years to recover, the team reports April 11 in Nature Communications.