The mild winter has led to some early arrivals at a wildlife centre in Gloucestershire.
A litter of seven harvest mice was born at WWT Slimbridge earlier this month.
At birth, each youngster was only the size of a baked bean but now they are about half the size of an adult harvest mouse. When fully grown they will still only be about 2.8in (7cm) long and weigh about the same as a 2p coin.
The mice, which are the smallest species of UK rodent, are part of a WWT collection of wetland mammals threatened with extinction in the wild.
WWT Slimbridge mammal manager John Crooks said: “Normally we wouldn’t expect to see them until at least February.”