Sociable weaver birds often have large nests around campsites, and are friendly little birds, a bit like our sparrows. They turned out to be good friends as well as good photo subjects! We'd been camping in the same spot for a couple of days and the birds often came to clear up our crumbs, but one day they started to mass beside a log and make a terrible racket. Looking more closely we saw there was a horned viper very well camouflaged under it. We'd collected kindling from that area so we were glad our little friends had given us the warning. The snake soon got fed up with the noise and moved on, and we were a little more careful picking up wood from then on.