UNCW professor makes studying penguins his life work

Steven Emslie, a professor of biology and marine biology at UNCW, and former undergraduate student Chelsea McDougall, excavate ornithogenic sediments (or bird soil) on Ardley Island in the Antarctic Peninsula. Photo Courtesy Dr. Steve Emslie

By Kate Elizabeth Queram

Published: Friday, September 27, 2013

Taking care not to face-plant on glacial ice floes, digging through debris from polar birds' nests, dodging painful smacks from Adelie penguin flippers - all in a day's work for Steve Emslie, a biology and marine biology professor at the University of North Carolina Wilmington.

"They're really strongly tied to their nest site, and even if you're a lot bigger than them, they will still charge at you and whack you with their flippers," he said. "It's like taking a ruler sideways and hitting it against your shin. They pack a powerful punch for a little bird."

After spending nearly 20 years researching the penguins, Emslie is familiar with the unique hazards of his work. Since the early 1990s, he's traveled throughout Antarctica excavating penguin nests and analyzing the remains, hoping to uncover details about the breeding and feeding habits of past and present bird colonies. Adelie penguins - much smaller than emperor penguins, with white stomachs and black heads and flippers - nest in the same location each year, leaving a well-preserved trove of organic matter that dates back centuries.

"It leads to an accumulation of sediments, pebbles, organic debris, guano, feathers, eggshell, bone and remains of chicks that don't make it," Emslie said. "It's like a freezer. They stay there forever. So what you get is a natural archive of tissues and remains that can date back hundreds to thousands of years."

Traveling around the continent, Emslie began by studying the distribution history of the Adelie, the most abundant penguin in the Antarctic.

"I looked at where they've been, where they are now and how that might relate to climate factors," he said. "They require a lot of things - open-water access to their nesting sites, ice-free terrain and pebbles, nearby food sources - so they're a good indicator species for all those factors in the marine environment."

If, for example, Emslie finds the remains of a colony that existed 5,000 years ago, he knows definitively that those same conditions existed back then. Emslie - working with undergraduate and graduate student researchers - uses radiocarbon dating to confirm the age of remains, which go back as least as far as 40,000 years.

"With that kind of record, we can ask more complex questions and put together a really nice story," he said.

For example, researchers about five years ago analyzed tissue samples to explore shifts in the penguins' diet as it relates changes in climate and other factors. 

"We found that their diet didn't really change for most of that 40,000-year record, until the last few hundred years," he said. "Then we found a distinct drop in carbon and nitrogen, indicating their diet switched from primarily fish to primarily krill."

That finding fit a previous hypothesis, suggesting that krill populations skyrocketed after whalers and sealers in the 1700s removed many krill-eating marine mammals from the southern ocean. The switch isn't bad for the penguins, Emslie said - krill swim in large swarms and are simply easier to catch than individual fish - but it does show how the birds adapt to changes in their environment.

"It has implications in terms of what might happen next," he said. "The krill is starting to run out, which means less for penguins overall. In the Antarctic peninsula, Adelie penguins are declining, and I suspect in the future they may disappear from that region. Their populations are definitely being impacted."

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