If the jungles of Africa and other great countries where the gorilla roams, have a bunch of spotlights setup. Then you should have a local light on him showing this. If someone is supposed to be taking his picture here with a camera's flash lighting him, then there should be a local light. If both of these things are not happening then no local light should exist. Local Light is artificial light. It should be lit with directional, natural looking, light. This will give the impression that natural light (sunlight) is what is lighting the scene.

Here is what I would do...

The lighting should be warmer.

The lighting should have a directional top lighting scheme.

Ambient Lighting from the light bouncing off of various plant life will provide a fill light with almost the faintest bit of green (maybe).

You can do a cheap caustic lighting by creating a 2d planar map to map on transparently to a light so that when the light shines it gives the illusion of passing throught branches. The map can be created in photoshop. However the distance from the branches and leaves from the gorillas is probably 5-15 feet. So the caustic lighting would not having any real detail. The fall off of the lighting would give it a resemblance of caustics but not be true caustics. So the appearence of lighting traveling through branches and leaves is hinted but not given. This method will also cut down on your render time. Caustics is very trying on the cpu. So doing it this way will only help.

Try a few things, you have a few weeks. Also keep in mind that you can render this thing out in passes and composite it within photoshop. At which time you can play with the values and what not. Not everything is done within Maya like Im sure you know.

At this point I would simply focus on modeling and texturing once your done with those things then worry about your lighting. Too much time can by devoted to lighting and even if it looks correctly lit your model and texturing can bring down the composition if it does not look right.

THIS IS MY CC AND I STAND BY IT