The fate of many penguin breeds may offer startling warning of the dangers of climate change. Andrew Darby reports.
The Age, Melbourne, Australia
IN YEARS past, a songbird upturned in a cage was the first warning of deadly gas in a mine. Above ground, an age of fossil fuels later, there are different signs - and disturbing silences - warning of climate change carnage.
In the sub-Antarctic, king penguins fledge fewer chicks if the parents must forage in warming seas. Rising waters are swamping limited nesting space for African penguins in Namibia. And because climate change's legacy varies capriciously, little penguins in Bass Strait seem to do better when the water temperature is up.
But it's on the west coast of the Antarctic Peninsula that the signal is clearest. The raucous cacophony of Adelie penguins has disappeared from the landscape as whole colonies collapse.
"On top of a single high rock I see an unbearably poignant tableau," recounts science writer Meredith Hooper in her book The Ferocious Summer: Palmer's penguins and the warming of Antarctica. She is witnessing the demise of a colony.
"One fluffy chick is standing, very still, on its pebble nest, with one adult. A skua stands next to them. Waiting. Death openly in attendance."
Ocean temperatures off the peninsula's west coast are up 1 degree in 50 years. Annual mean temperatures on the peninsula have risen three degrees - or 10 times the global rate. It is there, scientists have discovered, that humans are making weather - ozone depletion and greenhouse gases have strengthened the westerly winds.
It was in this part of the world, too, that the 3250 square kilometre Larsen B ice shelf, stable for 12,000 years, collapsed so spectacularly over just eight days in early 2002.
Earlier that summer 160 kilometres west across the peninsula from Larsen B, Hooper had arrived at the US Palmer station with longtime Adelie biologist Dr Bill Fraser who concluded that the breeding season at Palmer had gone to hell.
Adelies breed in summer on the few outcrops of Antarctic rock. In 2001-02 on an island cluster near Palmer, the rookeries were at first buried under repeated snowfalls. Then in high summer came the rarest of polar weather: rain.
Hooper watched as the snowstorms belted in. "If birds stand up to shift position, snow falls on the eggs to melt into a puddle. Eggs are crushed or kicked out of nests as birds try to deal with the snow. Or the eggs lie cold, flooded out."
Then after the surviving chicks fledged, the rain came.
"Cold doesn't affect the chicks. It's the rain, soaking their down, forcing them to shiver, using up vital calories in an attempt to keep warm."
Reproduction in the Palmer study area collapsed. An average long-term breeding success rate of 1.34 chicks per pair was measured by Fraser as collapsing to 0.55 chicks.
On one of the islands, Litchfield, 1000 pairs of Adelies nested 50 years ago. That summer, 12 chicks hatched - all to be taken by the crowding, predatory skuas.
"There are no sounds but the wash of the sea, the occasional calls of skuas," Hooper observed. "Every penguin is gone, the nests are abandoned. Listen to the silence. The silence of absence. The sound of failure."
Trouble for the Adelies didn't end at the breeding colony.
These are birds of the pack ice. Underneath it, swimming in meagre twilight, they find their food in winter. But along the western edge of the Antarctic peninsula, there is also a decline in sea ice.
Adelies are being displaced from their former ranges by more adaptable penguins usually seen in the sub-Antarctic: chinstraps and gentoos.
Hooper caught sight of a lone gentoo standing on the stubby station pier at Palmer. "I used to joke that gentoos were estate agents checking out potential property," Hooper ruminated. "Now here is a gentoo. Symbolically waiting."
These are real-time climate changes, not predictions for the future. They are unfolding in a matter of a few years.
In Hobart this month at the sixth International Penguin Conference as more scientists reported their worries the birds' value as sentinels for climate change became clearer.
"They depend on the ocean for survival, but they come on land to relatively easily monitored colonies," said Dr Susie Ellis, a former vice-president of the US organisation Conservation International, who surveyed the global state of the penguin at the conference.
"From there we can track what is happening out at sea."
This is what happens at the Crozet Islands in the far southern Indian Ocean, a refuge for more than 1 million king penguins. Data loggers fixed to kings follow them as they swim in as far as the polar ice edge, their spidery tracks building seasonal webs of their movements.
Researcher Celine le Bohec said the kings' breeding success depended on cooler seas. In the warmer El Nino years, it was lower because food that the deep-diving kings depended on was reduced.
A rise of just 0.3 degrees in water temperature coincided with a 10 per cent reduction in population survival.
Le Bohec saw this as a serious warning. "The king penguin population might be under heavy extinction risk in scenarios put forward by the International Panel on Climate Change," she said.
These risks also face a relatively tiny penguin population: the 70,000-strong African.
Jessica Kemper of the University of Cape Town scrambled over cramped coastal islets off Namibia that these birds use to nest and counted the hatching failures in places with a high risk of being swamped.
The scrappy little African's most important food basket, the Benguela current, also produces less for them when it is warm, and many birds do not make it back from their first year at sea.
Of all the threats that bedevil penguins, those of the temperate world are most imminent. Among the southern hemisphere's 17 species, 12 are red-listed by IUCN, the World Conservation Union, their populations tending to fall, and the most threatened are in temperate zones.
Competition from over-fishing and net entanglement, human disturbance, introduced predators and pollution are damaging the temperate small populations and challenging wildlife officials who would protect them. Two species of southern New Zealand, the yellow-eyed and erect-crested are listed as endangered, along with the northern-most penguins in the world, the Galapagos.
The conference heard of dozens of innovative ways of tackling these threats.
In Peru, saving Humboldt penguins meant controlling the digging of their ancient breeding grounds for guano. In Cape Town, industrial-scale cleaning methods have been developed to save African penguins from persistent oil pollution. And in western Victoria, a Maremma guard dog has successfully protected little penguins from foxes and cats.
But as Ellis surveyed the conservation of penguins, climate was clearly the most difficult challenge. At its predicted change rates, she said it was guaranteed to put greater pressure on penguins in the future.
There may be a silver lining for some. Australian biologist Lynda Chambers found that among the shallow roaming little penguins, the warmer water years tended to produce more chicks that were heavier. For these birds, higher-quality food was available closer to the breeding colony.
"Some species are taking advantage of the switch," acknowledged the conference's convener, Eric Woehler. "But clearly the over-arching concern at the moment is the uncertainties to do with climate change.
"It's our role to be able to document what is going on. We need greater understanding and in some places there isn't a lot of time."
The Ferocious Summer. Palmer's penguins and the warming of Antarctica by Meredith Hooper is published by Profile Books. London 2007.
