13 • A
10.Run the sand through a sieve to remove all
remaining beans.Part B: Multiple Prey Species
1.Bury 40 kidney beans, 30 pinto beans, and 20 lima
beans in the sand.
2.Design a table that will allow you to record an
identification number for each forager, the number
of each type of bean remaining in the pan before
each forager starts, the number of each type of
bean captured by each forager, and the time taken
by each forager to locate enough prey items to
survive.
3.Repeat Steps 4 to 8 from Part A. This time,
however, survival is ensured by finding any of the
following five combinations of beans:
4 pinto beans 3 kidney beans
2 lima beans 3 pinto beans and 1 kidney bean
3 pinto beans and 1 lima bean
As before, the forager must find one of these
combinations within 10 seconds or die of starvation.
As soon as survival is ensured, foraging must stop.
The time taken to find sufficient prey is recorded in
the table.
4.Construct a graph showing the relationship between
time taken to find sufficient prey to ensure survival
and the number of prey items remaining in the pan.Post-lab Questions
1.What type of foraging strategy — that of a specialist
or a generalist — was represented by each of the
situations in Parts A and B of this investigation?
2.Why were other group members required to turn
their backs while the forager looked for beans?
What does this prevent? Does this aspect of the
simulation represent what occurs in nature or not?
Explain.
3.Were there any beans left when all the foragers had
died in Part A or Part B? Do you think there might
be prey items left in a natural habitat? Why?
4.What happens as the food is depleted (that is, the
number of beans decreases) in the habitat? Why?
5.In general, which of the two types of foraging
strategies worked more quickly to allow individuals
to find enough food to survive? Why do you think
this was the case?
6.In Part B, did you use any particular strategy in
deciding what combination of prey to search for? If
so, what was it and why did you use this strategy?
7.Do you think this simulation truly represents natural
foraging activity? Why?Conclude and Apply
8.In nature, what features of both the prey and the
habitat would contribute to the success of an
individual forager? Were any of these features
simulated in this experiment? Explain.
9.In nature, how might a forager increase its efficiency
at finding prey? How might the simulation be
changed to represent this? Repeat Part B using
your changed simulation to test your new prediction.
10.How many foragers (represented by the number of
turns taken before all foragers died) were able to
survive in each of the two habitats (in Parts A and
B)? Explain your results.
11.Is it possible for the same species to act as both a
generalist and a specialist in its foraging behaviour?
Explain your answer.Exploring Further
12.Given sufficient quantities of all types of food, what
factors in real life might influence the choice of food
taken by a generalist?- (a)In nature, what do animals do when their food
supply is depleted?
(b)How might an organism try to ensure that there
continues to be sufficient food in a habitat to
support it and/or its young?
14.How might you change this simulation to
incorporate reproduction of prey or predators?
15.Repeat the procedures after changing the substrate
to simulate the effects of human interaction (for
example, by mixing stones, pieces of plastic, or
other substances into the sand). Compare your new
results with the previous trials for undisturbed
substrate. What did you find? Explain your findings
in a one-page essay.
If spreadsheet software is available, input the data into the
spreadsheet and use the computer to generate graphs that
illustrate the data.COMPUTER LINK
438 MHR • Unit 5 Population Dynamics