There are signs that the dormouse, which has disappeared from many parts of England, is making a comeback in woodland in Cornwall.
The dormice are not disturbed by Matt Lewis' monthly checks
National Trust staff on the Lanhydrock Estate are celebrating the first dormouse litter to be born after a three-year study into their nesting habits.
Staff from the Trust put up 25 nest boxes last year.
The first female to be spotted since the study began in 1999 was seen in the spring and now four youngsters have arrived.
Matt Lewis, a National Trust area warden, said: "The whole reason we are doing this survey is because dormice have become more endangered over the last 60 to 100 years.
"It's great news to know they are living here healthily and sustaining themselves and breeding.
"Even though we are disturbing them slightly every month they are still breeding in that box so it can't be bothering them that much."
It is now hoped the youngsters will rapidly increase their weight so they can hibernate through the winter.