氣候變化惹的禍：白毛動物恐將滅絕

White-furred animals are in danger of dying out because climate change is causing a fall in snow cover, leaving them exposed and vulnerable, a new study suggests.

一項新研究指出，白毛動物正面臨滅絕的危險，因爲氣候變化導致冰雪覆蓋範圍減少，從而讓白毛動物難以藏身、易受攻擊。

Scientists in Poland have been following the worrying case of the white-coated weasel, which sheds its tawny covering in the winter for a milky coat allowing it to blend effortlessly into its icy environment.

波蘭的科學家們一直在跟蹤調查白鼬這種令人擔憂的狀況。白鼬在冬天會褪去黃褐色的皮毛，長出雪白皮毛，以便輕鬆地融入冰雪環境中。

But researchers have discovered that between 1997 and 2007 the number of days with permanent snow cover in Białowieża Forest, Poland, halved, from 80 to 40.

但是研究人員發現，1997年至2007年間，波蘭比亞沃維耶扎原始森林被長期冰雪覆蓋的時間從80天縮短到了40天。

It means that the little creatures are being caught out in a completely unsuitable environment, where they are easy prey for predators like foxes and crows.

這意味着這種小動物將和環境格格不入，容易成爲狐狸和烏鴉等捕食者的獵物。

The team at the Polish Academy of Sciences found that on days when there was little winter snow cover, the number of white-coated weasels they managed to capture fell to as low as 20 percent of the total, suggesting the rest had been killed.

波蘭科學院的研究團隊發現，在冰雪覆蓋範圍很小的日子裏，他們能捕捉到的白鼬的數量下降到了獵物總數的20%，這意味着另外那部分白鼬都已被殺死。

Previously they would have been dominant, because their coats would have given them a survival advantage.

先前捕獲的獵物基本都是白鼬，因爲它們的白毛給自己帶來了生存優勢。

The problem is likely to affect other white-furred mammals and birds living in areas vulnerable to climate change such as the Arctic fox as the snow cover increasingly gives way to a landscape of greens and browns.

在一些容易受氣候變化影響的地區，那裏的其他白毛哺乳動物和鳥類很可能也被這個問題困擾，比如北極狐，因爲越來越多本應被冰雪覆蓋的地方露出了綠草和黃土地。

Scientists have recorded 21 mammal and bird species which turn white in the winter to hide themselves in snowy landscapes including the mountain hare, the Siberian hamster, the collared lemming, the white-tailed jackrabbit and the willow ptarmigan bird.

科學家記錄了皮毛會在冬天變白以在冰天雪地裏藏身的21種哺乳動物和鳥類，包括雪兔、西伯利亞倉鼠、環頸旅鼠、白尾長耳大野兔和柳雷鳥。

Author Dr Karol Zub, told The Telegraph: “Definitely the same rules apply to all seasonally moulting mammals and birds.

研究報告的作者卡羅爾·祖布博士告訴《每日電訊報》說：“同樣的規律肯定適用於所有季節性換毛的哺乳動物和鳥類。”

“According to studies on showshoe hares during periods when hares are colour mismatched weekly survival probability decreases by 3.3 - 6.5 percent. This seems not to be a big effect, but the cumulative effect over winter can seriously influence mortality of the species.

“根據對白靴兔的研究，當白靴兔的顏色不能融入環境時，它們單週的生存機率下降了3.3%-6.5%。這聽起來似乎影響不大，但是整個冬天的累積效應將會嚴重影響這類物種的生存。”

“It is very probable that in the near future white weasels and stoats will disappear completely from many areas of Northern Europe and North America.

“在不遠的未來，北歐和北美許多地區的白鼬很可能將完全消失。”

"They will either be replaced by brown morphs or they will evolve and moult later in the season, being only partly white for a relatively short period.”

“它們要麼被棕色的變種鼬取代，要麼進化成更晚換毛、白毛期相對更短的白鼬，而且在白毛期時，身上也只有部分白毛。”

Researchers also carried out tests using toys of brown and white-coated weasels to see if the colours were actually making a difference to predators.

研究人員還用黃鼬和白鼬玩具做了測試，看顏色是否對捕食者有影響。

When they set up camera traps they found dozens of animals, such as foxes, wolves and birds of prey had approached the white toys, but none had shown interest in the brown versions.

研究人員布好相機陷阱後，他們發現狐狸、狼和食肉鳥等數十種動物都接近過白色玩具，但沒有動物對棕色玩具表現出興趣。

The authors say both findings suggest that the decrease in white-coated weasels is due to an increase in detection by predators in a less snowy environment.

作者稱，這兩項研究都表明，白鼬數量下降緣於在冰雪覆蓋減少的環境中捕食者更容易發覺白鼬的存在。

The researchers are hopeful the animals will learn to adapt, but say they cannot rule out the animals vanishing entirely.

研究人員希望白鼬能學會適應環境，但也指出不能排除這種動物就此滅絕的可能性。

Weasels that do not change colour in the winter, are more likely to survive to pass on their brown-coated genes, increasing the numbers of the darker species.

那些在冬天不會變色的鼬鼠更可能生存下去，進而把褐毛基因傳遞給下一代，導致黃鼬數量增加。

Dr Zub added: “We should not underestimate the power of natural selection. We hope that along with future climate warming, autumn temperatures will also increase, providing an additional signal to the weasels to delay their moult.

祖布博士補充道：“我們不應低估自然選擇的力量。我們希望在未來氣候變暖的過程中，秋季氣溫也會隨之升高，能夠向鼬鼠額外傳遞延遲換毛的信號。”

The research was published in the journal Scientific Reports.

該研究發表在《科學報告》期刊上。