Wed, Apr 25, 2012 - Page 17 News List

Space pictures pick up lots more penguins
從太空數企鵝 越算越多

King Penguins walk in Ski Dubai at the Mall of the Emirates on Feb. 1.
國王企鵝二月一日在阿拉伯聯合大公國購物中心的Ski Dubai滑雪場內行進。

Photo: Reuters
照片:路透

Scientists counting emperor penguins from space have found twice as many of the birds in Antarctica as expected.

Using high-resolution satellite images to study each of 44 colonies around the coastline of Antarctica, experts said they put the total emperor penguin population at 595,000, or roughly double previous estimates of 270,000 to 350,000. Seven of the colonies studied had never been seen before.

A key advantage of satellites is that they can capture multiple images in one go, whereas visiting dozens of remote colonies in temperatures as low as -50 degrees Celsius would be hugely expensive and time-consuming.

Still, conducting a penguin roll-call from space is not simple. It took a special technique known as pan-sharpening to increase the resolution of the satellite images to differentiate between birds, shadows and penguin poo, or guano.

While some images remained tricky to analyze, Peter Fretwell, the team leader of the British Antarctic Survey, believes the overall population figure is correct to within a 10-12 percent margin of error.

The study by Fretwell and colleagues, published in the online journal PLoS ONE, marks the first time that researchers have counted the entire population of any species by satellite.

(Reuters)

從太空計算帝王企鵝的科學家發現,在南極的帝王企鵝數兩倍於預期。

在利用高解析衛星影像來探究南極海岸線周邊44個帝王企鵝棲地後,專家說,他們將帝王企鵝總數定在五十九萬五千隻,大約比之前估算的二十七萬至三十五萬隻之間多了一倍。研究的棲地中有七處之前未曾發現。

衛星的一個關鍵優勢是它們能一口氣捕捉到多個地點的影像,因為在低達攝氏零下五十度的溫度中,走訪數十個遙遠的棲地將是極度昂貴與耗時的工程。

儘管如此,從太空中點數企鵝並不簡單。它須採取彩色合成影像處理的特殊技術來增加衛星影像的解析度,以區分出企鵝、陰影與企鵝糞便,或鳥糞層的差異。

然而部分影像仍難以解析,英國南極調查所的團隊領導人彼得.弗瑞特威爾認為,企鵝整體數目在誤差範圍百分之十至百分之十二內是正確的。

這項由弗瑞特威爾與同僚共同進行並刊載於網路期刊「公共科學圖書館—綜合」的研究,是研究人員首度利用衛星來普查任一物種的整體數目。

(路透/翻譯:魏國金)

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