|Common Raven by Diliff Licensed under CC BY-SA 3.0 via Wikimedia Commons|
They used to be common but ten years ago there were only five pairs nesting in Sussex with all apart from the Lewes birds nesting on coastal cliffs. They mate for life, which can be more than twenty years.
Apart from their great size they can be identified by their heavy roman nose bill and shaggy breeches. In flight they have a very distinctive call, usually rendered as "prruk" in guidebooks. "The gentle prukking of the ravens" is a phrase that has stuck in my mind from somewhere. It is a sound best heard in remote silent mountain valleys.
As a footnote: I published this when on holiday in Morocco from the south-east side of the High Atlas mountains en route to the desert. In the desert the most noticeable birds were the ravens. They were of the subspecies C. c. tingitanus and are the smallest of the raven subspecies.