A 16-year survey on the Arctic Norwegian island of Svalbard found the reindeer there have declined in weight by an alarming 12 percent. The reduction in average body-mass is being blamed on global warming.

In research presented lately at a meeting of the British Ecological Society in Liverpool, scientists explain how rising temperatures are depriving female reindeer of nutrients during important phases of gestation.

Snow in Svalbard typically covers the ground for eight months of the year, which, combined with low temperatures, limits grass growth to June and July.

But as summer temperatures have increased by around 1.5 degrees Celsius, pastures have become more productive, allowing female reindeer to gain more weight by the autumn and therefore to conceive more calves.

However, warmer winters have brought with them greater rainfall which freezes when it settles on the snow, thereby locking out the reindeer from the life-sustaining food below.

As a result, female reindeer are becoming starved, causing them to abort their calves or giving birth to much lighter young.

The average mass of an adult reindeer in 1994, when the survey began, was 55kg, but by 2010 it had dropped to 48kg.

Professor Steve Albon, an ecologist at the James Hatton Institute in Aberdeen, said that because the mammals have a relatively high surface-area-to-volume ratio, they are not particularly energy-efficient.

Reindeer can often access the meager food sources beneath the snow by clearing it away with their antlers, but they cannot break through the hard ice.

Without access to the food in winter, calves are being born far lighter than they should be.

Numbers of reindeer have also soared in the past 20 years, meaning that those which are born are facing greater competition for food. “The implications are that there may well be more smaller reindeer in the Arctic in the coming decades, but possibly at risk of catastrophic die-offs because of increased ice on the ground,” said Albon.

The scientists also warned that a third of the world’s polar bears could disappear in the next 40 years due to melting Arctic sea ice.

一项对挪威北极区域斯瓦尔巴特群岛长达16年的调查发现，这里的驯鹿体重下降了12%，这一数字让人震惊。

全球变暖是驯鹿平均体重减轻的罪魁祸首。

日前，科学家们在利物浦英国生态学会的会议上展示了这项研究成果，他们解释在雌性驯鹿怀孕的关键阶段，气温升高令其营养不良。

通常，斯瓦尔巴德岛一年中有八个月都被白雪覆盖，而且气温极低，小草的生长期仅限于六月和七月。

但由于夏季气温升高了约1.5℃，草地变得更茂盛，这使得雌性驯鹿到了秋天会变胖、孕育更多小鹿。

然而，温暖的冬天带来了更多降雨，雨水落在雪地里会结冰，阻止驯鹿获得冰面下可以维持生命的食物。

结果，饥饿的雌性驯鹿就会流产或者诞下体重较轻的小鹿。

1994年调查开始时，一头成年驯鹿的平均体重为55公斤，到2010年，成年驯鹿的平均体重已经下降到48公斤。

史蒂夫•阿尔博教授是阿伯丁詹姆士赫顿研究院的生态学家。他表示，这种哺乳动物的表面积体积比相对较高，他们的能量利用效率不高。

驯鹿通常用鹿角清除积雪，获得下面为数不多的食物，但他们无法弄破坚冰。

雌性驯鹿冬天吃不到食物，生下来的小鹿就比应有体重轻得多。

驯鹿的数量在过去的20年里飙升，这意味着生下来的小鹿面临着更激烈的食物竞争。

阿尔博教授称，“这预示着，虽然未来几十年里很可能出现更多瘦小的驯鹿，但地上的冰面越来越大，它们因此存在灭绝的风险。”

科学家还警告称，随着北冰洋冰面的消融，全球三分之一的北极熊可能在未来40年内消失。(Chinadaily.com.cn)

    Words to Learn 相关词汇

    【怀孕】huáiyùn conceive become pregnant with

    【灾难性的】zāinànxìng de catastrophic disastrous, calamitous