Wing Anatomy Tutorial
In order to draw wings realistically, a basic understanding of wing anatomy is needed
In figure A we can see that the wing can be broken down into 3 moving points. Each of these points has its own range of movement and rotation as well as its limits. its is important to observe these movements and not break the limits unless for particular effect otherwise the wing will look unnatural. In particular, joint 2 doesn't have a lot of rotation or movement.
In figure B we can see that the wing isn't a flimsy item, it has to support the whole birds weight as well as achieving flight. It is very heavily muscled, esp. as the shoulder where most of the bird's chest, back, neck and stomach muscles feed into to it (birds are built around their wings). The exact muscles and bone length varies according to species, how they live and their weight.
In a closer look at the 'Primaries' and 'Secondaries' *covered later* we can see the difference between the two and how they again vary according to species. C is a Secondary from a goose, it is broad to provide plenty of lift with a blunt edge. D is a kestrel Primary, it is pointed like most hawks to help precise flying and has a noticeable notch along its leading edge (where the feather suddenly juts out). E is a Rook Primary, again like most primaries (except owls) it is pointed and quite rigid to stop it being bent by the air resistance. F is a Muscoy drake covert feather, it is blunt, soft and bendy much like a body feather. Looking closely at a feather you can see as in G that the feather is made of barbs zipped together with hooks, this means that you can get little tears on the edge of the feather than can be fixed again, helping preserve the feather for longer.
R shows a few variations of wing shapes, a Turn, a Eagle and a garden bird showing that the wing shape matches the lifestyle of the bird.
Now we know what the joints and muscles are, we can create a basic wing shape made of 3 parts as in J. The red line is the leading edge where the physical wing is. the blue line is the Covert which builds up the wing, gives it its strength and keeps it warm. The Green lined area is the Primaries and Secondary feathers.
Birds feathers overlap each other slightly to create a solid area. However, this is not haphazard. On the top surface of the wing the feathers are positioned so the leading (front) edge is sitting on top of the feather in front of it as seen in H. The underside of the wing is the opposite, the trailing (back) edge overlaps the feather behind it as in I. If this is difficult to visualize, hold two feathers together like in H, then holding them in the same position turn them over and you'll see they are like I.
Here is the top side of the wing in more detail.
The most important feather on the wing is the Flight feather. This is the feather that allows the bird to steer while flying, like a rudder on a boat. This one feather is not 'moulted' every year as it is too critical, only being replaced when the feather is completely lost meaning the bird cannot fly as well while this is happening. That is something that is life or death to a bird!
The coverts as already mentioned strengthens the wing where is doesn't need to be as flexible. L is a close up of the red stared area, showing how the feathers sit on top of each other rather than side by side in this particular area.
The Scapulars as they sound cover the shoulder blades.
The Secondaries are the feathers from the body to the Carpel joint. These tend to be large, broad and blunt ended to create the largest, flattest area as these provide the lift from the wings.
The Primaries are the feathers from the carpel joint creating the wing tip. Theses feathers tend to be long, pointed and are the ones that vary the most between species. The shape of these dictate how agile and fast the bird is, how it flies, whether or not it hunts, can glide or conserve energy, how often it needs to beat it wing and the wing span needed.
Detail of the underside of the wing.
The main differences are the axillaries, where the wing meets the body, which jut out over the wing. And the lining area which is concave (curves in and out to create a hollow) where the muscle' trailing edge is.
Here is a folded wing, We can see that the primaries (1) sit neatly on top of each over as to the secondaries (2) which also sit on top on the primaries but are much shorter.
Note- Primaries and Secondaries. Why do birds have them? The reason is because the bird has to moult every year (female birds usually moult once because they have to lay eggs, both moulting and egg laying use up a huge amount of body resources meaning that they cant do both so they have to moult when they are not laying, either sitting or before or after the breeding season. Male birds can moult several times a year).
When they moult they lose a certain percentage of feathers but how can they moult wing feathers and still fly? They do this by moulting out the Primaries while retaining the Secondaries. Because the Secondaries are the feathers that provide most of the lift, birds can fly well without their primaries although they are more clumsy and slower. The secondaries are replaced as needed as the resources needed to grow one or two feathers isn't as taxing as a large amount.
This is why when clipping a birds wing, only the primaries on one side should be cut because it unbalances the bird so it cant fly properly. If you cut the primaries on both sides, the bird can still fly because of its secondaries. The wing also needs re-clipping every year after it moults as the primaries are replaced. Cutting the secondaries is pointless because they re-grow and you should never ever cut the flight feather.
So as a rule of thumb when drawing, remember the Primaries are for precision flying and Secondaries create the large and flat area to provide lift
When drawing a wing it is important to remember it is not a flat object like a sheet of paper. The red stared area in S is curved to make the wing aerodynamic and well as the leading edge being where the muscle bulk is. The wing shape when seen as a cross section from the side in T is almost identical to an aeroplane wing with the leading edge being fat, leading into the covert area which is slimmer to the primaries/ secondaries which are very thin.
When working out a wing position, you can use shape blocks to aid you.
This is important to remember when drawing a bird's wing at an agile where it curves. When drawing the curves look at how a ribbon twists as in Y and applying that knowledge to the leading edge (while remembering that it has more thickness than a ribbon)
With all of this knowledge, constructing a wing in different positions is possible as in Z. One extra note about the primaries is that in some species such as the rook they are quite rigid and the bird 'turns' them slightly to aid its flying but in other birds such as an eagle, the primaries are quite flexible and effected but the air pressure. This means that when the eagle brings its wing down, the air pressure means the primary tips will bend upwards and when the wing is brought up, the primary tips will bend downwards as seen in the bottom left two drawing in Z. this can add a little extra action to your wing drawings.
Here is a little rough animation of a wing flying cycle from the side i did about 4 years ago. Click on image to play (you need flash player 8 for this to play)
These are the individual frames from the animated wing cycle. You can see the movements and rotation of the different joints and the effect of air pressure on the wing tips. On the down stroke the bird stretches out its wings as far as they go to get the maximum amount of lift while when it brings its wings up, it closes them up tightly to make them as small as possible so there's less drag and air pressure forcing the bird down.
Extra note on bird tails. Fig. N is a tail seen from the underside. as you can see the two outer feathers 1 and 2 are on top of the rest which also stacked on one another with the middle feather 3 at the bottom of both piles. Fig O shows the top view of the tail where, like the wing this is reversed, feather 3 is the topmost one on both stacks with feathers 1 and 2 being on the bottom of each stack on either side. This enables the bird to 'fan' its tail by using its tail muscles to twist feathers 1 and 3 further out with the feathers below also moving to fill the space. P and Q shows again how much variation you get in tails as again these aid the birds lifestyle and way of flying.
Finally, as with all animal drawings studying and practicing drawing the real thing in real life, video, pictures and anatomy books is the only way to understand and learn what things looks like. If you don't know what something looks like, then go out and find out how it really does. Never trust another artist to have got it right!
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