The days are shortening, the elderberries are blackening, and there's a definite whiff of autumn on the horizon.
For those birds which are only summer visitors to Britain, their hormones now respond to the seasonal changes underway, telling their bodies to pack on the fat and get ready for long, intercontinental flights ahead. Thousands of warblers and flycatchers, Swallows and martins are destined for unimaginable…