How Bird Wings Work: A resource for more accurately creating creature props
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From angel wings to fursuits, wings are a popular but often mis-represented  prop.

We'll look at the general structure of a wing and matching photos, then spread open a wing while it's still on the bird.

Here are the bones inside a wing.

The humerus has the tertiary feathers and connects to a bird's shoulder.

The radius and ulna  have the secondary feathers, where they meet the humerus is the elbow.

connecting those two parts is some webbing and stretchy ribbon of tendon.

This is the birds hand, there's three half-hearted fingers and the primary feathers.

The birds first finger is the alula, its feathers let a bird fly at slow speeds without falling out of the air.

Let's look at some poses.

See the gap between the feather groups?  The parts of the wing are distinct and can be treated as parts, there's nothing mystical about a wing.
Here's a gap on a  live bird between the black edged primary feathers and the red spotted secondary feathers.  

Loosely folding up the wing with the hand pointing backward makes that pretty heart-shape you see on costume angel wings.  All the structures are still there, 
the wings just appear rounded.

opening the wing and keeping the hand pointed backward creates the "guardian" pose, like on the back of the US quarter or the wings on any angel or demon 
ever to appear in a Japanese Anime.

Extending the wing fully creates a smooth surface for flying kind of like a airplane wing.  In art we tend to portray bendy feathery wings, but bird wings exist to 
be airfoils.

Human: "Hey Rudy, I need you to fly to the chair, okay? Fly to the chair.  Good man flies to the chair.  Okay let's have you spread your wing for the camera"
Parrot: "Ohhhhh!"
Human: "I'm going to spread your wing, okay? Wanna wrestle?  He loves wreslting... yeay you do, you love wrestling... this way I'm not being mean he just 
thinks we're wrestling. Rar! Rar!"
Parrot: "Rar-rar-rar-rar-rar!"
(Lots of wrestle noises)
Human, laughing: "So as you can see the wing has a fair amount of stretch and flex to it, so those joints don't just fold up and down the twist around back and 
forth."