Work began this week to prepare for construction work on the new Waitrose supermarket in Malmesbury.
Developers Simons said ‘enabling work’ has been taking place to cut back trees and bushes to clear the area.
Izy Hodgkinson, a spokesman for Simons, said: “We have fenced the project off but will add more fencing around the trees that will remain to protect them from the construction works.
“We will cut back some bushes and trees to clear the area before the bird nesting season starts.
“We have employed a professional tree surgeon to carry out these works to ensure great care is taken.”
Recent archaeology work on the site has finished and the developer’s finding are due to form an exhibition in the town hall later this year.
Plans for the store at the back of the Avon Silk Mills got the go-ahead last July after the government backed Wiltshire Council’s approval.