Borneo 2016

It's hard to overstate just how impressive a sight this is. As you can see, orangutans are highly dimorphic. Males have strange flappy face-pads called flanges, which females find attractive - yet males may wait 20 years (or more, or never) before developing them. Fully mature males are also twice the size of females and grow large throat sacs, all of which are characteristics associated with dominance.