Adélie penguins called the West Antarctic Peninsula their summer breeding turf for decades and then, about 20 years ago, another species, the gentoos, started showing up and the Adélie  population took a steep decline.

That sparked questions in the mind of a University of Delaware researcher: Were they competing for the same limited food and habitat resources? And were the gentoos the cause the Adélies' decline?
“We set out to explore whether the Adélies and gentoos were eating out of the same lunch box, so to speak,” said Megan Cimino, a doctoral candidate in the University of Delaware's College of Earth, Ocean and Environment and the lead author of a study reported recently in Scientific Reports.

It turns out, that even where the populations of the two species overlap, their feeding strategies – both target krill –  are different enough that one species isn't out-competing the other. But figuring that out took high tech tools such as tagging both species of birds to track movement and feeding patterns and use of an underwater robot that allowed researchers to pinpoint exactly where the food was and where the birds were going to get it.

The technology produced hundreds of thousands of data points that Cimino reviewed before concluding that one species wasn't out-competing another for the same food resources. The findings leave lingering questions about why gentoos expanded their range and why the Adélie population is declining so dramatically.

The Western Antarctic Peninsula is one of the most rapidly warming places in the world and Cimino's previous work with Adélie penguins there looked at shifts in climate and weather conditions. A colony of penguins in the West Antarctic Peninsula. Palmer Research Station is in the background.  Megan Cimino, University of Delaware