Traditional societies and the wildlife that depends on them are disappearing. Can we preserve these fragile species? Or is the pressure to develop too great in our world? This week's field report comes from Ethiopia where one of the most endangered birds in the world, the Ethiopian Bush Crow, teeters on the verge of extinction as the traditional societies they rely upon disappear. This beautiful bird needs a particular regime of grazing and scrub to survive, but the societies that provide the right habitat are fast disappearing as development and modernisation takes over. Monty Don explores, with renowned writer Jared Diamond, the value of traditional societies and what we lose when they finally vanish.