Morphology and Locomotion

Question 1

What is a defining characteristic of the bones of many seabirds that is crucial to their ability to fly?

Answer 1

Bones are pneumatic (hollow) with internal struts that increase structural rigidity (they are also fused together)

Question 2

Describe the key features of the thorax of seabirds that enable them to fly

Answer 2

1. Furcula (wishbone): two collarbones fused together where ends meet
2. Sternum (breastbone): flight bones are attached to a projection called the keel

Question 3

What are the two major flight muscles in seabirds?

Answer 3

1. Pectoralis
2. Supracoracoideus
   Both are attached to the sternum (keel)

Question 4

What is the function of the pectoralis?

Answer 4

Lowers wings for downstroke (power stroke)

Question 5

What is the function of the supracoracoideus?

Answer 5

Raises wings for the recovery stroke

Question 6

What is the function of the alula?

Answer 6

Facilitates landing by allowing birds to create drag

Question 7

What are the two muscle types in seabirds?

Answer 7

1. Red-muscle fiber
2. White muscle fiber

Question 8

What is the function of red-muscle fiber?

Answer 8

Endurance oriented aerobic activity (ex: walking, sustained flight)

Question 9

What is the function of white-muscle fiber?

Answer 9

Explosive anerobic movements (ex: predator evasion short explosive flight)

Question 10

Define aerodynamics

Answer 10

Demands imposed by getting off the ground and staying in the air

Question 11

What are the two key features of aerodynamics?

Answer 11

1. Lift
2. Drag

Question 12

Describe lift

Answer 12

An upward force that gets birds off the ground and keeps them in the air

Question 13

What produces lift?

Answer 13

The movement of air around and past an airfoil

Question 14

What is an airfoil?

Answer 14

Any shape that produces lift and drag (for birds it is a wing)

Question 15

Describe the mechanism required to produce lift in birds?

Answer 15

1. Air flowing over the top of the wing must reach the back of the wing at the same time as the air flowing underneath the wing
2. Wings are curved so… the top of the wing is longer relative the bottom of the wing
3. Air flowing over the top of the wing must go faster than air flowing underneath the wing
4. The result of this difference in speed is lower pressure above the wing and higher pressure below the wing

Question 16

How do feathers function as airfoils?

Answer 16

• They are asymmetrical
• The outer vane is narrower than the inner vane
• The result is a curved feather

Question 17

Why is it important that bird feathers have a curved shape?

Answer 17

Similar to the shape of the bird wing the curvature is necessary for creating the pressure difference required to generate lift (higher pressure underneath the feather lower pressure on the top). The pressure gradient is the result of the air at the top of the feather flowing faster than the air on the bottom.

Question 18

What is the importance of drag?

Answer 18

Reduces lift by slowing the air moving over the wing

Question 19

Define turbulence

Answer 19

Disruption of air flowing over the wing

Question 20

Define thrust

Answer 20

Foward force generated during flapping flight (utilized to gain lift)

Question 21

Wing loading

Answer 21

The ratio of weight to wing area (how much body weight is weighing down the wings)

Question 22

How do you calculate wing loading?

Answer 22

Body mass/Surface area (kg/m^2)

Question 23

Aspect ratio

Answer 23

Ratio of a wing’s length to it’s width

Question 24

Describe wing shape if you have a high aspect ratio

Answer 24

Long and skinny (narrow)

Question 25

Describe wing shape if you have a low aspect ratio

Answer 25

Wings have similar length and width

Question 26

Why is aspect ratio imporatant?

Answer 26

Higher aspect ratios reduce drag (facilitate gliding)

Question 27

Describe the wing loading and aspect ratio of a bird that has a high wingbeat frequency

Answer 27

• High wing loading
• Low aspect ratio
• Both

Question 28

Describe the wing loading and aspect ratio of a bird that has a low wingbeat frequency

Answer 28

• Low wing loading
• High aspect ratio
• Both

Question 29

Describe gliding flight

Answer 29

• Common in birds with high aspect ratio
• Utilize weight to overcome air resistance when moving forward
• Only large birds glide regularly

Question 30

Describe soaring flight

Answer 30

• Utilizing atmospheric processes to gain altitude
• Common in birds with low wing loading and high aspect ratio

Question 31

Describe flapping flight

Answer 31

• Up and down movement of the wings generates thrust
• Downward stroke (“power stroke”): generates the most thrust (wing forms a solid airfoil)
• Upward stroke: Tips of primaries separate allowing passage of air through slots (reduces friction)
• Proximal portion of the wig moves less and provides the most lift
• Distal portion of the wing generates thrust

Question 32

If a bird is a better diver than flyer, is their wing loading low or high?

Answer 32

High

Question 33

If a bird is a better flyer than diver, is their wing loading low or high?

Answer 33

Low

Question 34

Why is underwater locomotion energetically costly?

Answer 34

Water is more dense and viscous than air

Question 35

What are the 3 types of water locomotion?

Answer 35

1. Swimming on the surface
2. Wing propulsion
3. Foot propulsion