How to fix existing .blend files that use the bird rig, but don't render with the feathers or the eyes showing properly:
If you want to make sure that the bird rig renders the feathers and the eyes properly, the objects have to be made visible. To do this:
Do the same thing for the eyeballs by select one of the eyeballs in object mode, go to the Materials properties and select the bird_eye_ref.001 to change the transparency of the iris so that it shows up, and then select the bird_eye_ref.002 to change the transparency of the pupil.
NOTE: If you want to change the color of the iris (bird_eye_ref.001) - for instance, to make them crazy bright red! - you can do it the same way you change the color of any object with the Diffuse panel.
Margo Burns July 29, 2012
Blender version 2.63