NASA satellite reveals surprise about penguin poo on Danger Islands

12 Dec 2018

Image: © Valerie/

NASA-funded research is helping conservationists to track the Adélie penguin by looking at its poo from space.

When we think of satellite photography, we tend to think of scrolling endlessly through random parts of the world on Google Earth, or finding where you need to go using a number of different map apps.

However, a team of NASA-funded scientists is using satellite photography to do something totally different: search for penguin poo. Guano, to use its technical term, is being sought after near the remote Danger Islands off the tip of the West Antarctic peninsula.

The poo belongs to the Adélie penguin, a species whose population has declined rapidly in some areas despite their global population increasing. Not only that, but the species can provide an early warning of threats to Antarctica’s delicate ecosystem.

Graduate student Casey Youngflesh and associate professor Heather Lynch from Stony Brook University in New York are part of the team that has been tapping into Landsat satellite imagery to see if the Adélie penguins’ diet has been evolving in response to Antarctica’s changing climate.

Over the past few years, these scientists have been tracking the distribution and abundance of penguins across the barren landscape, with a previous survey revealing 3.8m breeding pairs. However, the latest Landsat imagery has revealed several previously unknown massive penguin populations.

Rather than detecting these penguins individually, the team was able to detect their presence based on the stains left by their guano on the ice.

Satellite image of the small, remote Danger Islands off the coast of Antarctica.

Satellite image of the remote Danger Islands near the tip of the West Antarctic Peninsula, holding the largest population of Adélie penguins on the peninsula. Image: NASA

Surprising discovery

“Male and female penguins take turns incubating the nest. The guano left behind builds up in the same areas occupied by the nests themselves,” Lynch said. “We can use the area of the colony, as defined by the guano stain, to work back to the number of pairs that must have been inside the colony.”

Incredibly, the images taken by Landsat can help tell the researchers what the penguins are eating because of the colour of their guano. Explaining further, Lynch said that white guano indicates they are mostly eating fish, while pink and red guano indicates they are mostly eating krill.

After poring through years of images, the team was surprised to find that while the Adélie penguins’ diet did show changes from year to year, no consistent pattern was apparent.

Speaking of this finding, Youngflesh said: “This was a big surprise, since the abundance and distribution of Adélie penguins has changed dramatically over the last 40 years and scientists had hypothesised that a shift in diet may have played a role.”

Colm Gorey was a senior journalist with Silicon Republic