So long, Dasher, Dancer and Blitzen: Researchers say wild reindeer in the Arctic are getting smaller and weaker and are dying younger, with global warming the likely cause.
The average weight of adult reindeer on Svalbard, a chain of islands north of Norway, had fallen to 48kg from 55kg in the 1990s, as part of sweeping changes as temperatures rose, they said.
"Warmer summers are great for reindeer but winters are getting increasingly tough," Professor Steve Albon, an ecologist at the James Hutton Institute in Scotland, who led the study with Norwegian researchers, said.
Less chilly winters meant that once-reliable snows fell more often as rain that could freeze into a sheet of ice, making it harder for the herbivores to reach plant food. Some reindeer starved, and females often gave birth to stunted young.
In summer, however, plants flourished in a food bonanza that ensured healthy females were more likely to conceive in autumn, with a pregnancy lasting about seven months. The wild herd under observation had expanded to about 1400 animals, from about 800, since the 1990s.
"So far we have more, but smaller, reindeer," Prof Albon said.
The rising population also meant more competition for scarce food in winter.
Sea ice in the Arctic Ocean this year continued to melt during the polar winter - the first time this has been observed in modern history.
Most studies of climate change around Svalbard have focused on polar bears that hunt seals at sea, rather than year-round land residents such as reindeer, Arctic foxes and Svalbard rock ptarmigans.
Arctic fox numbers had risen slightly because they thrived in severe ice winters by scavenging dead reindeer, said Eva Fuglei, a researcher at the Norwegian Polar Institute and the Fram Centre, who was not involved in the reindeer study.
"All the weak reindeer die - the sick, the elderly and calves," she said. But that meant foxes struggled to feed the next winter, because only the fittest adult reindeer had survived.
Meanwhile, US scientists are concerned over a sudden surge in the amount of methane gas being released into the atmosphere.
The researchers say efforts to tackle climate change will be undermined unless methane levels are brought under control.
- Reuters / BBC / RNZ