Predator-Prey Relationships
Background
In this case study you will look at one of the most famous sets of data ever collected on a
predator-prey relationship. Lynx are a type of wildcat that inhabit the forests of Canada and prey
on snowshoe hare. In some areas, the snowshoe hare provide over 70% of the lynx diet. As a
result, the population growth curve of the lynx should show a relationship to that of the
snowshoe hare. The data on this relationship is shown in the graph below. Study the data as
carefully as you can before answering the questions that follow.
Data
Population Numbers of Hare and Lynx by Year
100000
Population Numbers
90000
80000
70000
60000
50000
40000
Hare Numbers
30000
Lynx Numbers
20000
10000
1895
1900
1903
1905
1908
1909
1910
1912
1915
1918
1921
1924
1927
1930
1933
1934
1936
0
Year
Questions
1
Which animal is the predator and which is the prey?
2
As the hare population increases what happens to the population of the lynx? Why do you
think is?
3
As the lynx population increases what happens to the population of the snowshoe hare?
Why do you think is?
4
The population growth curves are said to fluctuate, what do you think this means?
5
Using the graph to help, how many years are there in one fluctuating cycle of the hare
population?
6
What factors could be responsible for the unusual number of hare in 1895?
7
A good predator-prey relationship keeps the two populations “in balance”, what do we mean
by this?
8
What would happen to the forest environment if the lynx started being hunted for their
skins?
Challenge
9
Explain the changes, if any, the introduction of a second predator of the snowshoe hare
would have on the predator-prey relationship shown above?