Scientist had assumed penguins returned to the exact same nesting area each year to breed. If true, this posed serious problems for their colonies with climate change and the melting of ice where they breed. New research out of the University of Minnesota reveals that emperor penguins may be much more willing to relocate their nesting grounds than previously thought. If true, this gives them a much better chance at being able to adapt to changing environmental conditions than scientists previously had considered them able to do.
Up until this study, most researchers had assumed that emperor penguins were philopatric, returning to the same nesting location year after year. This new study used satellite images to determine penguins weren’t as philopatric as they thought. They were able to find six separate instances over a three-year period where emperor penguins didn’t return to the same area to breed. In addition, they found a new colony of penguins on the Antarctic Peninsula which could be an indication of penguins relocating to a new area.
Technology was behind this major debunking of long held assumptions. High-resolution satellite images allowed researchers to view the entire Antarctic seacoast, as well as all sea ice in the area, something they couldn’t previously do. Emperor penguins are the only animal species on the sea ice in this area, so the researchers were able to identify their presence through the guano stains they left on the ice. They were also able to determine penguin colonies which were thought to be completely isolated were in fact not isolated all, allowing for the penguins to easily reach other colonies previously thought impossible.
The lead author of the study, Michelle LaRue, noted the emperor penguin colonies seemed to appear and disappear over the years, and this was a behavior that challenged the prevalent scientific view about these penguins. She stated, “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. 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.”
Emperor penguins are a species which have been extensively studied over the years. The colony which was featured in the film “March of the Penguins” has been studied for more than 60 years. Researchers, going on the assumption that these penguins always nested in the same spot, had found during a five-year period in the 1970s that the colony had declined by 50%. During this period, 6,000 breeding pairs of the penguins had dwindled down to 3,000 breeding pairs. At the time, the decline was assumed to be due to decreased survival rates as a result of the penguins not being able to adapt to receding sea ice.
Now knowing that these penguins may not have actually died, but simply relocated to a different colony to breed, completely changes assumptions which have been made for years. This new information means that researchers and scientists will need to come up with new models of why penguin colonies fluctuate in size.
The study was first shared at the IDEACITY conference in Toronto, Canada on June 20, 2014. In addition, the research findings will be published in the upcoming issue of Ecography.
(Photo courtesy of Christopher Michel)