THURSDAY November 1 will see the start of the biggest ever bird survey to hit the UK.

The British Trust for Ornithology is mobilising an army of 50,000 birdwatchers to undertake a stock-take of the UK’s birds with the aim of understanding how recent changes to our climate and habitats are affecting Britain’s birds.

Bird Atlas 2007-11 is a four-year project covering the whole of Britain and Ireland during the winter and breeding season. It aims to check the numbers and distributions of over 250 species, including the 40 red-listed and 121 amber-listed Species of Conservation Concern.

It is hoped that the results will set the agenda for bird conservation in the next two decades, helping to answer questions such as:

• Is barn owl conservation working?

• Have willow tit and hawfinch become extinct in some counties and regions?

• Are birds spreading further north as a result of climate warming?

• Where are the remaining breeding concentrations of turtle doves and nightingales?

Dawn Balmer, the Bird Atlas coordinator said: “The aim is to cover every 10km square in the UK, and BirdWatch Ireland will be organising the same sort of survey in Ireland.

“We are delighted with the enthusiasm birdwatchers have shown for the Atlas. There is a real sense of concern about how birds are coping with changes to our climate and their habitats.”