Managed to take a photo, at an extreme distance, of a Diedericks cuckoo, also known as the rain bird. This bird is always very vocal before it rains, the more insistent the call, the closer the rain. A better weather forecaster than the met office.
Click on photos to enlarge.
This photo taken at a 100m +. The bird always sits right at the top of a tree while singing, in this case, a willow tree. Here I manage to photograph it in full song.
Virtually impossible to get close to this bird as it has a clear view from his high perch and flies away if you approach too close. The photos just give you glimpse of the birds beautiful iridescent green plumage.
Other birds who give an indication of coming rain are the red breasted cuckoo and Burchell's coucall. Coucall's call sounds a lot like water being poured from a bottle, just more melodious. Google Burchell's coucall for recordings of it's song.
The photo above from the Internet.