Harvest mice found thriving 15 years after reintroduction efforts

Volunteers find nests made by descendants of creatures released by student in 2004

As an idealistic PhD student, Wendy Fail's ambition was to reintroduce harvest mice to Northumberland. She painstakingly bred 240 mice in captivity and in 2004 released the elusive mammals on to a coastal nature reserve with plenty of reedbeds for them to hide in.

When not a single harvest mouse - Britain's smallest rodent - was recaptured in subsequent trap surveys, Fail concluded that her efforts to reintroduce them had been unsuccessful.