Lecture 7

Question 1

what is biomechanical analysis

Answer 1

analysis performed using phylogenetically-controlled independent contrasts.

Question 2

How do you measure transient load lifting?

Answer 2

• put harness around hummingbird connected to a color coded string
• place hummingbird on ground and then they try to escape by flying up.
• measure how much weight they can lift.

Question 3

What happens to hummingbirds when they live/fly at higher altitudes?

Answer 3

1. body mass increases
2. wing size increases
3. stroke amplitude increases (measure of sweep and angle of wing)

Question 4

True or false: At maximum load lifting all birds have the same stroke amplitude

Answer 4

true

Question 5

What changes depending on the bird and elevation? what does this mean?

Answer 5

sweep angle - means that during a hover, birds at low elevation have more room to increase their sweep angle

Question 6

Does power cost go up as elevation goes up?

Answer 6

yes but not significantly

Question 7

Why does power not increase as elevation increases?

Answer 7

1. increase in wing size
2. increase in stroke amplitude
   these mechanisms help compensate for higher elevation

Question 8

What is power margin?

Answer 8

how much extra power the bird has available beyond hovering to do extra things eg: escape from predator

Question 9

How does power margin change with increasing elevation? what does this mean?

Answer 9

power margin decreases so birds at high elevations have less excess power available than birds at lower elevations

Question 10

Do territorial birds have more burst power available to them?

Answer 10

yes