Name: _______________________________
Deer: Predation or Starvation
Introduction: In 1970 the deer population of an island forest
reserve about 518 square kilometers in size was about 2000
animals. Although the island had excellent vegetation for feeding, the food supply obviously
had limits. Thus the forest management personnel feared that overgrazing might lead to
mass starvation. Since the area was too remote for hunters, the wildlife service decided to
bring in natural predators to control the deer population. It was hoped that natural
predation would keep the deer population from becoming too large and also increase the
deer quality (or health), as predators often eliminate the weaker members of the herd. In
1971, ten wolves were flown into the island.
The results of this program are shown in the following table. The Population Change is the
number of deer born minus the number of deer that died during that year. Fill out the last
column for each year (the first has been calculated for you).
Year
Wolf Population Deer Population Deer Offspring
Predation
Starvation
Deer Population
Change
1971
10
2,000
800
400
100
+300
1972
12
2,300
920
480
240
1973
16
2,500
1,000
640
500
1974
22
2,360
944
880
180
1975
28
2,224
996
1,120
26
1976
24
2,094
836
960
2
1977
21
1,968
788
840
0
1978
18
1,916
766
720
0
1979
19
1,952
780
760
0
1980
19
1,972
790
760
0
1. Graph the deer and wolf populations on the graph below. Use one color to show deer
populations and another color to show wolf populations.
Analysis
1. Describe what happened to the deer and wolf populations between 1971 and 1980.
2. What do you think would have happened to the deer on the island had wolves NOT been
introduced?
3. Most biology textbooks describe that predators and prey exist in a balance. This "balance
of nature" hypothesis has been criticized by some scientists because it suggests a
relationship between predators and prey that is good and necessary. Opponents of this
hypothesis propose the following questions:
Why is death by predators more natural or "right" then death by starvation?
How does one determine when an ecosystem is in "balance"?
Do predators really kill only the old and sick prey? What evidence is there for this
statement?
What is your opinion of the balance of nature hypothesis? Would the deer on the island be
better off, worse off, or about the same without the wolves. Defend your position.
Name:
Biomes at MoBot
Objective: Understand the plants, animals and climate that characterize each biome of the world.
Site: http://mbgnet.mobot.org/ - Missouri Botanical Gardens
Browse each biome and fill out the chart below.
Biome
Type of Plants
Types of Animals
Details & Climate (weather)
Rainforest
Tundra
Taiga
Desert
Temperate Forest
Grasslands
*Browse the site to find the answers to the following questions.
1. The trees that live in the taiga are all very similar. Collectively, these trees are called:
2. How do trees in the taiga protect themselves from fire (check under "taiga facts")?
3. Go to the temperate deciduous forest link and locate the graph that compares its rainfall to that of other
biomes. What two biomes receive the most rainfall and how many inches per year do they receive?
4. Go to the link that asks "what causes seasons?" Describe in your own words what causes the seasons.
5. Go to the leaf identification section. Identify the leaves below.
6. Go to the link for the desert biome, why does a desert get so cold at night?
7. Name the four major deserts of North America. (Look under the "deserts of the world" link).
8. What is the world's largest desert and where is it located?
9. In order to be classified as a "tropical rain forest" a forest must be located between what two Tropics.
10. Where can you find a rain forest in the United States?
11. Where is the tundra located and what is its most distinctive feature?
12. What is a lichen and where do they grow? (look under tundra plants)
13. What are the three types of grasslands found in the United States?
14. 14. Look under "Grasslands of the World". What are grasslands called in Africa? What are they called
in the U.S.?
15. There are three freshwater ecosystem links at the top menu. What are the three categories?
16. What is the longest river in the world? What is the longest river in the United States?
17. Name a fish, a bird, and a reptile that you would find near a lake.
18. Go to the rivers link and answer the question "What is a watershed?"
19. The top menu has three categories for marine ecosystems. What are they?
20. Within the shoreline ecosytem link are several subtopics that describe different types of shorelines.
Pick one of the types of shorelines and write a short description.
Deer Predation Answer Key | Deer Predation downloadable .doc file