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A thriving
"hotspot" of 1.5 million Adelie penguins, a species fast declining in
parts of the world, has been discovered on remote islands off the Antarctic
Peninsula, surprised scientists said Friday. The first bird census of the
Danger Islands unearthed over 750,000 Adelie breeding pairs, more than the rest
of the area combined, the team reported in the journal Scientific Reports.
The group of
nine rocky islands, which lie off the northern tip nearest South America, in
the northwest Weddell Sea, housed the third- and fourth-largest Adelie penguin
colonies in the world, they found. "It is certainly surprising and it has
real consequences for how we manage this region," study co-author Heather
Lynch of Stony Brook University told AFP.
Just 160
kilometres (100 miles) away on the west of the peninsula — a thin limb jutting
out of West Antarctica — Adelie numbers have dropped about 70 percent in recent
decades due to sea ice melt blamed on global warming. "One of the ways in
which this is good news is that other studies have shown this area [the eastern
side of the Antarctic Peninsula] is likely to remain more stable under climate
change than the western Antarctic Peninsula," said Lynch.
"So we end
up with a large population of Adelie penguins in a region likely to remain
suitable to them for some time." Adelies are one of five penguin species
that live in and around the Antarctic continent. A medium-sized penguin, they
grow to about 70 centimeters (almost 28 inches) tall, and weigh three to six
kilograms (about seven to 13 pounds). They are identified by a white ring
around the eye.
They are
carnivores, and krill — shrimp-like creatures that are commercially fished in
the area — is an Adelie staple. The Danger Islands group was discovered thanks
to Earth-monitoring satellites, said the research team from America, Britain
and France. "This is called the Danger Islands for a reason," said
Lynch. "The area is covered by heavy sea ice most of the year, and even in
the height of summer it is difficult to get into this region to do
surveys."
'Very lucky'
Even the most
visited of the isles, Heroina Island at the chain's northeastern tip, receives
only about one ship landing per year. Evidence of the previously-unknown
penguin colony first emerged in data from the Landsat Earth-monitoring
satellites run by NASA and the US Geological Survey. Lynch and her team
"then went and looked at higher resolution commercial imagery to confirm
the guano staining that our algorithms had picked up in the Landsat
imagery," she said.
When the Landsat
data originally suggested the presence of hundreds of thousands of penguins on
the islands, she thought it "was a mistake". "We were surprised
to find so many penguins on these islands, especially because some of these
islands were not known to have penguins." Then followed a field expedition
for a census using a combination of drone footage, pictures taken on the
ground, and an old fashioned walk-about headcount.
"We were...
very lucky to have a window of time where the sea ice moved out and we could
get a yacht in," said Lynch. The Danger Islands, said the team, has felt
the ravages of climate change less than the western peninsula, and knew very
little human activity. Now it turns out, the area may need stronger protection
from overfishing.
"The most
important implication of this work is related to the design of Marine Protected
Areas in the region," said Lynch. "Now that we know this tiny island
group is so important, it can be considered for further protection from
fishing." In addition to Adelies, the team also found about 100 nests of
gentoo penguins, and about 27 nests of chinstrap penguins. The polar regions
are warming more rapidly than the rest of Earth as heat-trapping greenhouse
gasses from fossil fuel-burning build up in the atmosphere.