A 16-year survey on the arctic Norwegian island of Svalbard found the reindeer（驯鹿）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 will explain how rising temperatures are making female reindeer difficult to obtain nutrients during important periods of being pregnant.
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℃, grasslands have become more productive, allowing female reindeer to gain more weight by the autumn and therefore to conceive（孕育）more calves.
However, warmer winters have brought with them greater rainfall which freezes when is settles on the snow, therefore locking out the reindeer from the life-supporting food below. As a result, female reindeer are becoming starved, causing them to give birth to much lighter young. The average mass of an adult reindeer in 1998, when the survey began, was 55kg, but by 2016 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（表面积与体积比）, they are no particularly energy efficient.
Reindeer can often access the inadequate food sources beneath the snow by clearing IT away with their antlers（鹿角）, 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 increased rapidly in the past 20 years, meaning that those which are born are facing greater competition for food. “The implication（含义）are that there may well be more smaller reindeer in the Arctic in the coming decades, but possibly at the risk of catastrophic die-offs because of increased ice on the ground,”said Professor Albon Despite the gloomy findings, reindeer appear to be suffering less from the impact of climate change than some other arctic species.
