Effects of Moonlight on Predation…..INTERPRETING BAR GRAPHS

Ain’t I cute?

How Much Does Camouflage Affect Predation on Mice by Owls?

About 50 years ago, D.W.Kaufman investigated the effects of a mouse’s coat color in a specific environment on the rate of nighttime predation by hungry owls. He also investigated the effects of the amount of moonlight on this predation as well.

He did this by placing a pair of mice, with different coat colors, into an enclosure with a hungry owl. He recorded which mouse was caught first (if no mouse was caught within 15 minutes, he recorded a ‘0’.)

He repeated this method multiple times

Both dark soils and light soils were used on the enclosure ground.

Presence/absence of moonlight was also recorded

The Experiment

Dark Coat

Light Coat

Dark Coat

Light Coat

Full Moon No Moon Full Moon No Moon

Num

ber

of

Mic

e C

au

ght

Num

ber

of

Mic

e C

au

ght

A: Light-Colored Soil B: Dark-Colored Soil

10

00

5

15

20

25

35

30

40

10

20

30

40

35

25

15

5

Results

Interpret the Data

1. Graph A shows data from the light-colored soil enclosure, while graph B is data from the dark-colored soil enclosure (all other aspects are the same.)

a) What are the independent variables (those tested by the researcher); which axis has the independent variables?

b) What is the dependent variable (that responding to the variable being tested); which axis has the dependent variable?

2. Analysis

a) How many dark brown mice were caught in the light-colored soil enclosure on a moonlit night?

b) How many dark brown mice were caught in the dark-colored soil enclosure on a moonlit night?

c) On a moonlit night, would a dark brown mouse be more likely to escape predation by owls on dark- or light-colored soil? Explain your answer.

3. Is a dark brown mouse on dark-colored soil more likely to escape predation nder a full moon or with no moon? How about a light brown mouse on light-colored soil? Explain.

4. Under which conditions would a dark brown mouse be most likely to escape predation at night? How about a light brown mouse? Explain.

5. What combination of independent variables:

a) led to the highest predation level in light-colored soil enclosures?

b) Led to the highest predation level in dark-colored soil enclosures?

6. What relationship, if any, do you see in your answers in 5 a) and 5 b) above?

6. What conditions are most deadly for both colors of mice?

7. Combining the data shown in both graphs, estimate the total number of mice caught in moonlight versus no-moonlight conditions. Which condition is optimal for predation by the owl on mice? Explain your answer.