If you live in Europe, mature deciduous trees offer a very special service to help you: a short-term weather forecast brought to you by chaffinches. These rust-red birds with gray heads normally sing a song whose rhythm ornithologists like to transcribe as “chip chip chip chooee chooee cheeoo.” But you’ll hear that song only on a fine day. If it looks like rain, the song changes to a loud “run run run run run.”
