I had fun doing the feathers around the eye area.
Golden Eagle

This bird is a clever bastard. He is standing in water, making a perfect circle with his wings over the water. If he stands absolutely still, a dumb fish will come right under his beak looking for shelter. This poor fish will think he has found the shade from a nice tree or bush growing out of the water – and not a clever hungry bird looking for dinner.
It’s both a beautiful sight, and a brilliant hunting strategy.
If you love odd looking birds, then the great frigate is your man. The male frigate has a giant red puffy sack on his throat, which he inflates during mating season like a balloon. Actually, a male will inflate the “gular sac” and shake his head vigorously from side to side, attracting the attention of lady birds flying by. Which, in bird speak, is almost the equivalent of a floppy air-man used at car dealerships – doing a crazy air-fueled dance to stop traffic – only to sell himself as a mate and not to sell used cars.
In any case, a truly weirdly wonderful bird.
I am proud of this one, good eyes, good lines, not overworked.
According to my two seconds of googling, the harpy eagle is the largest and most powerful raptor in the Americas, and one of the largest in the world. So his glare is well deserved. Do not mess with him. He will back up that threat with some muscle and sharp bits.