A Satellite Census For Penguins

• APRIL 20, 2010

For Penguins, a Satellite Census

Biologists Count Hard-to-Find Birds With Photos Supplied by Intelligence Agency

By ROBERT LEE HOTZ

Minden

Emperor penguin colonies, like this one on Cape Roget, are widely spaced in Antarctica, making it difficult to conduct a census of the birds.

MCMURDO, Antarctica—Bird-watcher Philip Trathan is counting the emperor penguins here—from space.
In the first complete census of these well-known birds, the British wildlife ecologist and his colleagues are scanning high-resolution satellite photos of Antarctica for penguins, like military analysts searching for Iranian rocket sites. In fact, their precision imagery comes from the U.S. National Geospatial Intelligence Agency. The photos are part of the roughly $25 million of commercial satellite images the agency buys every month for use by the Central Intelligence Agency and the Defense Department.

 

Tracking Penguins in Antarctica from 400 Miles Up

3:32

Researchers are using satellite data to track penguins and seals across the coldest region on earth without disturbing them - and without leaving home. WSJ's Robert Lee Hotz reports.

"You can count individual birds," said Dr. Trathan, a penguin ecologist at the British Antarctic Survey, who is part of an international census team.

Their penguin census, which will be completed later this year, is the latest application of satellite mapping techniques that are transforming perceptions of Antarctica, where millions of square miles of ice blend into a wilderness of white, and only penguins are truly at home. In many ways, this shifting snowscape is as uncharted as the day explorers first sighted its mainland almost 200 years ago.

"Until last year, we had better maps of Mars than of Antarctica," said Paul Morin, director of the University of Minnesota's Antarctic Geospatial Information Center, which is funded by the U.S. National Science Foundation to use the unclassified intelligence imagery in science projects like the penguin survey. "We can now see one of the most inaccessible places on Earth, on demand," Mr. Morin said.

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Landsat Image Mosaic of Antarctica, USGS, NASA

A Landsat image of Cape Washington in Antarctica shows a brownish smudge at center that is guano from large emperor penguins.

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Landsat Image Mosaic of Antarctica, USGS, NASA

A Landsat image shows a guano stain at upper right from large emperor penguins in Antarctica.

With the newest high-resolution imagery, researchers can detect anything on the continent larger than an end table. At that scale, a four-foot-tall, 90-pound emperor penguin is just large enough to show up in a single pixel. Dressed by nature in darkly formal feather-wear, an emperor penguin stands out in high contrast against the ice, even when viewed by a camera moving at four miles a second in an orbit 423 miles overhead.

Still, the emperor penguins complicate the count by huddling together for warmth. On an especially cold day, as many as 10 of them can cram together on a square meter of ice—a space slightly larger than a single pixel. "If you have so many pixels of penguins," said mapping expert Peter Fretwell at the British Antarctic Survey, "you have to decide how many penguins per pixel." Wildlife biologists estimate the count will turn up between 200,000 and 400,000 breeding pairs.

Living across the continent's 5.4 million square miles of polar ice, the emperor penguins are a bellwether that can help researchers detect subtle changes in climate and ocean conditions affecting all of Antarctica. Other penguin species wax and wane in response to changing regional winds, temperature trends and commercial fishing. But so far, no one knows how emperor penguins have responded to the changes, because there has been no easy way to find them all.

"Emperors are a really tricky species to get a handle on," said Dr. Trathan. "At the moment, nobody really knows how threatened emperor penguins really are."
It's no wonder. The birds make themselves at home in two of Earth's most inaccessible environments. No other bird dives deeper underwater, as far as 1,500 feet. No other creature breeds on the sea ice during Antarctica's winter darkness, when temperatures drop to 80 degrees below zero and winds top 100 mph.

Penguins Under Pressure

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Robert Lee Hotz/The Wall Street Journal

An international team of scientists is researching how Adélie penguins in Antarctica are coping with rapidly changing ice conditions and commercial fishing.

• More photos and interactive graphics

For years, field biologists based here at the U.S. McMurdo Station have tracked meandering emperors, bobbing like off-balance bowling pins, as they slip, slide and belly-flop over ridges of wind-rippled snow.
They have stood on stepladders to count the birds in congested formations, and hung cameras from helium-filled balloons to record their numbers more reliably.

They have bugged penguins with radio transmitters and shadowed them by jet with airborne infrared sensors that could detect a birds' body heat at a distance. Such techniques proved too intrusive and expensive for a systematic census.

The new census is not the first time penguin watchers have tried satellites. By chance, researchers last year discovered they could detect vast stains of penguin excrement on the ice using older low-resolution satellite images. That revealed the locations of 38 emperor colonies, 10 of them never seen before, Dr. Trathan and his colleagues reported last June in the journal Global Ecology and Biogeography.

Still, they couldn't actually see any penguins until they gained access to the newest images, which the intelligence agency buys from commercial satellite operators DigitalGlobe Inc. in Longmont, Colo., and GeoEye Inc. in Dulles, Va..

Scientists hope the newest images will allow them to study emperor penguins without disturbing them—and without leaving their home laboratories.

"If you can do it from space," said Dr. Trathan, "you can do it from your desk."

Write to Robert Lee Hotz at sciencejournal@wsj.com

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