Cattle last grazed on the common during the 1920s
Cattle have been introduced to heathland in Surrey which was ravaged by fire nearly three years ago.
Five Belted Galloway cattle have been introduced to four hectares of Ockley Common, part of the Thursley National Nature Reserve, near Godalming.
Natural England said it was the first time the area had been home to cattle since the 1920s.
A series of fires in July 2006 damaged Dartford warbler nest sites and harmed sand lizards and butterfly colonies.
Thursley National Nature Reserve covers 400 hectares of heathland, woodland and bog system.
James Giles, Natural England reserves manager for Thursley, said: "We are grazing the cattle on this internationally important bog system to help increase the variety of plants and insects."