Illustrating birds is a specialty of mine, and understanding just how detailed they are is part of that. That’s what makes the work fun, because there’s no end to the variety of detail with so many bird species.
This diagram gives a great illustration of how a feather is put together. Birds groom themselves often to keep their feathers in good condition, thus keeping the interlocking ‘barbs’ looking neat.
There is nearly no end to the combination and patterns of feather colors on birds. Iridescence, scalloped, vividly, or earthy tones can all be observed in the world of birds. Parrots and other tropical birds tend to possess the most brightly colored plumage.
Beaks are adapted to the bird’s diet, whether it be cracking seeds and nuts, or tearing meat from prey. Feet are similarly adapted to the diet, suited specific to the environments where the food is found.
Eyes are as varied as feathers. Tropical, woodland, and predatory birds all have eyes suited to there environmental niches. Bird eyesight is many times better than human vision. They can see in the ultra violet spectrum, and polarized light( which is said to aid them in migratory flight).
Parrots in particular have a funny thing they do with their eyes called ‘pinning’. They can shrink and expand their pupils rapidly according to mood, and other behaviors. It can be a sign of excitement, or impending attack dependent on how the bird is perceiving the situation.
All images borrowed from google search. I do not own them, and I’m only using them as examples here.