Flight, Wings, and Feathers

What physics laws contribute to lift?

Bernoulli’s Law + Newton’s 3rd Law

Bernoulli’s Law

• static and dynamic pressure have an indirect relationship

• speed increases = dynamic pressure increases

• top of wing decreases in static pressure

• high static pressure from bottom wants to go to top

• Lift from static pressure underneath

Dealing w/ profile drag

• reduce surface area (tucking wings)

• alula: help maintain laminar flow at low speed

Dealing w/ induced drag

• reduce area of wing tip: narrow, pointed wings OR slots between feathers

• flow low enough to disrupt vortices - pelicans

• TAKE ADVANTAGE OF THEM - V-formation

What are feathers?

• specialized epidermal growths

• 90% beta-keratin protein

• lightweight, strong, durable

• provide a solid, yet flexible surface

• high surface to weight ratio = ideal for flight

Basic anatomy of a feather

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Evolution of feathers

Basic feather anatomy

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Types of feathers

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Which orders lack pterylae/feather tracts?

ratites and penguins

Pilodirection

stand feathers up/puff

Wing Parts

• Primaries

• Secondaries

• Alula

• Coverts

Feather care

• preening

• uropygial gland

• powder downs

• bathing

• anting

Preening

Uropygial gland

Powder downs

Bathing

Anting

Aspect

feather wear

Purposes for aspect

breeding, anti-predation, etc.

Where does color in bird feathers come from?

the barbs

Pigmentation colors

• carotenoids

• melanins

• porphyrins

What makes porphyrins special?

they create the greens + reds in turacos (Musophagiformes)

Structural colors

white, most of blues and greens, and iridescence