July 22, 2010
Penguins Threatened By Their Fear Of The Dark
Will Adelie Penguins, attempting to cope with climate change, go extinct because they can't find food in the darkness of the Antarctic winter? A recent paper published in the scientific journal Ecology presents this finding: Adelie Penguins need both ice and light, even just twilight, to find food in the winter.
As climate change causes the winter ice to retract south into the darkness, penguins won't have what they need to survive and could ultimately face extinction as a result. Like songbirds needing trees, these penguins rarely stray very far from sea ice.Researchers from PRBO Conservation Science, H.T. Harvey and Associates, Stanford University, NASA, and the British Antarctic Survey tracked the penguins' year round movements for the first time using geolocator tags. Over a three year period they documented the penguins' need for both ice and light during the winter, as reported in the Ecology paper.
"Penguins living near the Antarctic Peninsula are being forced to migrate southward to find ice in the winter. This is in direct contrast with penguins on the other side of Antarctica at the Ross Sea, and those elsewhere in Antarctica, which still need to migrate northward to find light and favorable ice in the winter. Ultimately penguins around Antarctica will face darkness or lack of ice "“ they'll just reach that boundary from different directions," says Grant Ballard, PhD, of PRBO Conservation Science and lead author of the tracking study.
This is the first study to show the complete migratory and wintering locations of Adelie Penguins. The researchers found that penguins made use of ocean currents to facilitate annual migrations averaging almost 13,000 km (~8,100 miles), and that they travel more than twice as fast on the return trips from their wintering locations to begin breeding than when they depart after breeding. They also concluded that this migration pattern evolved in relatively recent times, since the last ice age.
"From studying the long-term history of this species in Antarctica, we know that animals are actually very good at adapting to fluctuating conditions in their environment. They do this by changing their migration routes or altering other feeding behaviors. In this case, however, ice conditions are changing so rapidly the penguins may not be able to adapt in time," says Dr. Ballard.
This study builds on another recent publication in Ecological Monographs by many of the same scientists that indicates major changes in sea ice extent will be underway within our lifetimes given the present climate trajectories.
The Ross Sea is projected to be the last place on Earth where sea ice will persist and where Adelie Penguins and other pack-ice species can exist. The findings reported by these researchers also underscores the need to designate the Ross Sea as a Marine Protected Area, slow the progression of climate change, and look for adaptation strategies to some of these unforeseen effects of climate change.
This research, funded and supported by the National Science Foundation and the US Antarctic Program, was conducted at two colonies in the southern Ross Sea, which is south of New Zealand.
Reference: Ballard, G., V. Toniolo, D.G. Ainley, C.L. Parkinson, K.R. Arrigo, P.N Trathan. 2010. Responding to climate change: Adelie penguins confront astronomical and ocean boundaries. Ecology 91(7):2056-2069.
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