Winter is a season of life or death for Britain's birds

For Britain's birds, the weather in January is absolutely crucial. Cold, hard winters mean death; mild ones greatly increase their chances of survival. To see the difference in fortunes, we only need to compare two winters just over a quarter of a century apart: the Big Freeze of 1962-63 and the winter of 1988-89, one of the mildest on record.

Winter 1962-63 has gone down in meteorological history as the winter to end all winters. From New Year's Day until the end of February snow fell somewhere in Britain every single day, and temperatures remained six degrees below the usual average at a numbing 0C.