assignment

UNDERSTANDING HEAT REGULATION IN OWLS

Owls range in size in North America: the largest being the great gray owl to the smallest being the northern pygmy owl. Surface area of an organism increases approximately as the square of the organism’s length, whereas the volume increases approximately as the cube of the organism’s length. Owls are shaped like a cylinder, and we can use the surface area (SA) and volume (V) formulas of cylinders to understand heat regulation in owls.

SA = 2πrh + 2πr2 V = hπr2

where h = height of owl, r = radius of owl’s body, and π = 3.14. First, read the assigned pages and pay particular attention to surface area, volume, and thermal inertia. Second, answer the questions on the following page and turn in the page for extra credit.

Great Gray Owl

Northern Pygmy Owl

Name: 1. Calculate surface area and volume for each owl and fill in the blank spaces.

Owl species Body height (cm)

Body radius (cm)

Surface area (cm2)

Volume (cm3)

Great gray owl 54 10 Saw-whet owl 17 4 Long-eared owl 30 5 Boreal owl 24 4 Screech owl 20 4 Barn owl 34 6 Pygmy owl 14 3 Great horned owl 50 8 Barred owl 40 7

2. Graph the relationship between (a) height and surface area and (b) height and volume.

3. Which owl would have the greatest thermal inertia? 4. Which owl would need to invest more energy to keep warm while hunting on a cold winter

night?

0

2

4

6

8

10

12

14

16

18

0 10 20 30 40 50 60

Vo lu

m e

& S

ur fa

ce A

re a

Th ou

sa nd

s

Height