Dr Rebecca Biddle, of Twycross Zoo, spoke at a launch event at Everards Meadows in March.
She said: “Following last year’s reintroduction programme, we’re already seeing encouraging signs, including evidence of breeding.
“There’s often a perception that conservation is focused on more exotic species, but British wildlife is just as important.
“The hazel dormouse is a brilliant example – a small, distinctive species that plays a key role in our ecosystems and deserves protection.”