World's largest reindeer herd plummets
The world's largest wild reindeer herd has fallen by 40% since 2000, scientists have warned, BBC says.
They say that the animals, which live in the Taimyr Peninsula in the northernmost tip of Russia, are being affected by rising temperatures and human activity.
This is causing the animals to change their annual migration patterns.
The research has been presented at the Fall Meeting of the American Geophysical Union (AGU).
"There is a substantial decline - and we are also seeing this with other wild reindeer declining rapidly in other parts of the world," said Andrey Petrov, who runs the Arctic Centre at the University of Northern Iowa, US.
The Taimyr herd is one of the most monitored groups of reindeer in the world. The animals have been tracked for nearly 50 years by aerial surveys and more recently by satellite imagery.
The population reached a peak of one million in 2000, but this latest research suggests that there are now only 600,000 reindeer.