WORK at the former Royal Mail Delivery Office in Princes Risborough has been delayed, due to the presence of swifts.
The birds are nesting at the property in Bell Street, which means it cannot be demolished until they have flown away.
Planning permission has been given at the site to knock down the current building and put up a two storey building with five flats on the first floor and a Morrisons Local on the ground floor.
It was due to be knocked down by developers, W.E.Black on May 22.
The RSPB site said: "Swifts are now on the Amber List - they're birds of Conservation Concern. Their numbers have declined dramatically in the past ten years; we're not sure why, but one of the possible reasons is that their nest sites are being destroyed."
At last Tuesday's Princes Risborough Town Council meeting Cllr Will Streule said the information in the ecological report from the developers was not correct.
He said The Countryside Group raised the issue, as did The Heritage Society and a number of residents.
He pointed out that the plans said to demolish the building between September and April but they then tried to do it at the end of May.
The Bucks Free Press has requested a comment from W.E.Black.