Canon 5D, 700mm, F6.3, 1/400 second at ISO 100.
Reviewing some of my Tanzania photos when I saw this image in my files. For some reason it escaped my attention previously, perhaps that suggests haphazard management on my part!
I believe the bird is a Brown Snake Eagle (Circaetus cinereus) however, if someone knows better and wishes to correct me, please do so. A little research reveals that this species is reasonably common throughout central and eastern Africa and so, thankfully, isn't currently regarded as endangered. As its name suggests, it feeds on snakes and also other small prey such as lizards.
For further check out the Tanzania Gallery.