New satellite images challenge the longstanding notion that emperor penguins always return to the same area to nest: It seems they’re more willing to relocate than we previously thought. Being able to adapt to their changing environment would be a boon for the long-term future of this beloved Antarctic species.
Emperor penguins (Aptenodytes forsteri) -- of “March of the Penguins” fame -- aren’t officially listed as endangered or even threatened, though scientists are increasingly concerned that the receding sea ice may affect those who breed on it. The colony in the movie is called Pointe Géologie, and it’s been studied for more than 60 years. Researchers have always thought that the birds were philopatric, returning to the same location to nest every year -- a problematic tenacity should their habitats shrink.
Scientists working at Pointe Géologie typically look for previously banded birds to return to the colony. But over five years in the late 1970s as the Southern Ocean warmed, they noticed that the colony declined by half: from 6,000 breeding pairs to 3,000. The decline was attributed to warming temps negatively impacting the penguins’ survival.
But now, high-resolution satellite imagery makes it possible to view the entire coastline and all the sea ice. A team led by Michelle LaRue from the University of Minnesota examined images of nesting locations, using telltale signs of guano stain. The images revealed that Pointe Géologie is not isolated at all: Plenty of other colonies are within an easy travel distance.
“It’s possible that birds have moved away from Pointe Géologie to these other spots and that means that maybe those banded birds didn’t die,” LaRue says in a news release. “We need to revisit how we interpret population changes and the causes of those changes.”
The team found six instances in three years where emperor penguins didn’t return to the same place to breed. They appear to be moving among colonies. Additionally, the team also discovered a new colony on the Antarctic Peninsula that may represent relocated penguins.
“Our research showing that colonies seem to appear and disappear throughout the years challenges behaviors we thought we understood about emperor penguins,” LaRue explains. “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. These birds didn’t just appear out of thin air -- they had to have come from somewhere else.”
Image: Michelle LaRue, University of Minnesota