This image is a composite and painting. It is two images from the eagle at our zoo and one image of a mountain range out near Vegas. The background is created entirely with mixer brushes. He took 2 days to paint and finish with dodge and burning the lighting effects. Every feather had to be painted so it flowed correctly.
The eyes were enhanced with a curves layers to pop the marbling effect in the eyes and also brightened with my special color dodge layer (see my blog for details on how to execute that on my roller bird step by step tutorial) https://terributlerphotography.com/painting-in-photoshop-step-by-step-breakdown/
Both the branch and the bird had a brown and gold gradient map applied so the images looked like they were captured under the same setting of lighting. This really helped to make the colors in the bird's feathers rich and vibrant without over saturating the image.