We've noticed a significant decline in the number of swallows with us this summer, and it seems we're not alone. Paul Stancliffe from the British Trust for Ornithology has said that the swallows are here, "but seem to be in much lower numbers than we would expect".

A summer without swallows feels somehow incomplete - so why are there so few swallows in the UK this year? As it turns out, there are a number of possible explanations.

More...