Poop Stains on Antarctic Ice Reveal Unknown Penguin Migrations
Emperor penguins, the well-studied species popularized by the 2005 wide-screen documentary "March of the Penguins," are apparently much more adaptive than researchers thought.
A new study from the University of Minnesota indicates the earth-bound birds, which scientists believed returned to the same nesting area yearly, changed their home locations over relatively short periods of time to adjust to changes in the environment.
But according to a university news release, satellite images used to examine penguin poop stains show it took only a few years for emperor penguins, which generally always move in large groups and are the only known species to live outside on the sea ice, to move the locations of their nesting grounds, presumably in response to climate changes.
The study's conclusions, unveiled at the IdeaCity Conference in Toronto on June 20 and to be published in an upcoming issue of the journal Ecography, were further supported by the recent discovery on the Antarctic Peninsula of a new colony of the penguins, which presumably migrated from the historic nesting site on the group of rocky, ice-covered islands known as the Géologie Archipelago.
"Our research showing that colonies seem to appear and disappear throughout the years challenges behaviors we thought we understood about emperor penguins," says the study's lead author, Michelle LaRue, a researcher from the university's College of Science and Engineering, as well as a research associate with the school's Department of Earth Sciences.
"If we assume that these birds come back to the same locations every year, without fail, these new colonies we see on satellite images wouldn't make any sense," she continues in the release. "These birds didn't just appear out of thin air -- they had to have come from somewhere else. This suggests that emperor penguins move among colonies. That means we need to revisit how we interpret population changes and the causes of those changes."
The "March of the Penguins" colony that convened on the archipelago has been studied for more than 60 years; scientists have visited the colony yearly to see, in particular, if the birds banded by researchers return.
Over five years in the late 1970s, the Southern Ocean warmed; at the same time, the penguin colony on the Géologie Archipelago dropped from 6,000 counted breeding pairs to 3,000 pairs. Scientists thought rising temperatures were lowering survival rates.
Today's high-resolution satellite imagery reveals that the Géologie site hasn't been isolated at all -- that plenty of colonies are in easy travel distance for the penguins.
"It's possible that birds have moved away ... to these other spots and that means that maybe those banded birds didn't die," LaRue said. "If we want to accurately conserve the species, we really need to know the basics. We've just learned something unexpected, and we should rethink how we interpret colony fluctuations."