Was listening to moorland birds (Scottish Borders) yeaterday evening, Lapwings, Curlews, Grouse, Oyster Catches, Sky Lark etc. But I was also hearing a bird I could not identify, it was a much deeper sound (but not a Bittern) at first I wondered if it was a Lamb but it wasn't, I'm sure it was a bird.
Any ideas of what it could have been.