Vervets treat a camp as their own, which makes them the easiest animals to photograph and the ones I feel slightly guilty photographing, because there is no fieldcraft in it, just a monkey deciding you are furniture. One sat by a tree, one worked a rail, a baboon held court from a fork higher up.
The frame is the one with the baby on its back. A vervet went along the railing at full clip with the little one clamped on, and there was no time to do anything but swing the lens and hope. That is most of wildlife photography honestly stated: react, and check later whether you got it.
All on the 135, base ISO to 100. Easy subjects, but the running one earned its keep; everything about it, the speed, the grip of the baby, the blur behind, only holds because a fast enough shutter happened to be set.