They're My Babies' Girls Release 250 Harvest Mice into the Wild

Turning somersaults in the corner of a field in Devon this week were the fluffy results of an audacious wildlife project launched by two 13-year-old girls.

- Helena Horton

Best friends Eva Wishart and Emily Smith had been upset to find out that harvest mice are threatened in England because of modern farming practices and habitat loss.

So, two years ago, the girls took matters into their own hands and decided to replenish local harvest mice stocks themselves. Since then they have bred dozens of the tiny rodents in Wishart's family garage. Yesterday, with the Guardian and the TV naturalist Chris Packham along to watch, they released 250 into a reserve near Tiverton.

Harvest mice are Britain's smallest rodent, at just 70 millimetres long, with sandy fur which blends into the grasses they nest in. The mice are an important prey species for larger animals, and are a major predator of insects, which can be agricultural pests.

Harvest mice are the only mammal in Britain to sport a prehensile tail which can grasp objects such as grass stalks.