A type of old world monkey, this Mantled Guereza lives at the San Diego Zoo. My initial thought was to convert the photo to a black and white image. But, when I saw the beautiful brown eyes and the light to dark
green gradient, I was convinced not to.

Nikon D810
Nikkor 200-500mm f5.6
1/125
f5.6, -2/3 EV
ISO 90