Nick Upton / Harvest mouse (Micromys minutus) cleaning its nose on Common hogweed (Heracleum sphondylium) flowerhead after release, Moulton, Northampton, UK, June.

Nick Upton / Harvest mouse (Micromys minutus) on Common hogweed (Heracleum sphondylium) flowerhead after release, Moulton, Northampton, UK, June.

Nick Upton / Harvest mouse (Micromys minutus) on Common hogweed (Heracleum sphondylium) flowerhead after release, Moulton, Northampton, UK, June.

Nick Upton / Harvest mouse (Micromys minutus) clinging to a Common hogweed (Heracleum sphondylium) flowerhead with its feet and tail after release into the wild, Moulton, Northampton, UK, June.

Nick Upton / Harvest mouse (Micromys minutus) using its gripping tail to aid its descent of a Common hogweed (Heracleum sphondylium) stem after release into the wild, Moulton, Northampton, UK, June.

Nick Upton / Emily Howard-Williams with Labrador Tui, who has been trained to sniff out feeding stations visited by Harvest mice (Micromys minutus), Moulton College, Northampton, UK, June. Model released.

Nick Upton / Plastic bottle containing grain fitted into a feeding station equipped with an automatic Radio Frequency Identification (RFID) monitor for surveying Harvest mice (Micromys minutus) after release into...

Nick Upton / Emily Howard-Williams checking that the automatic Radio Frequency Identification (RFID) monitor built into a Harvest mouse feeding station reads a microchip inserted into it and relays the information...

Nick Upton / Harvest mouse (Micromys minutus) being inspected prior to release at a field site, Moulton College, Northampton, UK, June. Model released.

Nick Upton / Emily Howard-Williams placing a grain feeding station equipped with an automatic Radio Frequency Identification (RFID) monitor to survey Harvest mice (Micromys minutus) in field enclosure after releas...

Nick Upton / Emily Howard-Williams placing a grain feeding station equipped with an automatic Radio Frequency Identification (RFID) monitor to survey Harvest mice (Micromys minutus) in a field enclosure after rele...

Nick Upton / Roger Trout and Jia Min Lim with an Edible / Fat Dormouse (Glis glis) excavated from its winter hibernation burrow in woodland where this European species has become naturalised, Buckinghamshire, UK,...