An influx of wolves preying on reindeer herds has triggered a state of emergency in the Sakha Republic, in north-eastern Russia. Squads of hunters will pursue the wolves in a three-month "battle" from 15 January, officials say.
The discovery helps answer a tantalising question: does getting old impact the athletic abilities of animals just as it does people? While it might seem obvious that it would, many eminent biologists and researchers have assumed otherwise. They have argued that most animals tend to die before age wearies them.