Bird Flight Anatomy: Feathers, Adaptations, and Generating Lift, Exams of Biology

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Feathers & Bird Flight

Types of Feathers

• Down Feathers:

primarily for

insulation

• Contour Feathers:

cover and smooth

the body of bird

• Flight Feathers:

d’uh, for flying.

Flight Feather Structure

Barbs off

shaft have

interlocking

barbules

and hooks

to hold

feather

together.

vane

How could you test these

hypotheses?

• Fossil evidence
• Small dinosaur

with downy-like feathers over entire body (discovered 2001)

• Suggests that

feathers evolved for insulation.

Feather Tracts-feathers arranged in

zones or bands.

Reduction of Weight

• Lighter bones
• Reduction of number of bones
• Loss of dense teeth.

bird

bat

human

Rigid Framework

• Ribs modified to

join vertebrae with

sternum

• Fusion of bones

and tight

articulations.

Flight Feathers on Wing and Tail

• Wing feathers –

Asymmetrical (remiges)

• Tail feathers-tend

to be more symmetrical (rectrices).

Adaptations for Flight

• Flight Feather

Locations ٠ Primaries attached to bones of the hand ٠ Secondaries attached to the ulna.

Generating Lift

• Air over wing

traveling faster, less air pressure

• Air under wing travel

slower, more air pressure

• Difference results in

greater pressure applied under wing: lift!

The Problem of Stalling

• Angle of wing is

important

• Too Steep of angle

and turbulence results reducing lift.

Reducing Drag

• Induced Drag is

curling of air from underwing to top of wing tip

• Solutions:

٠ Reduce wing tip area ٠ Slot the wing tip into ‘winglets’

Reducing Drag

• Friction Drag is due to

air moving over the bird

• Solution: thin leading

edge slicing through the air.