Environmental Science
Lab 6: Endangered Species
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Exercise 1: Giant Panda and Poaching
Part A: Limits on Growth
1. What is the probability that this panda population will go extinct in the next 120
years with a carrying capacity of 25? What if there were no limits on the panda
population? (Hint: Choose exponential and rerun the model.)
2. How was the probability of a 50% decline affected by reducing the carrying
capacity? How was it affected when you increased the carrying capacity?
3. Based on this model, would you expect restoration of habitat (so that it could hold
more pandas) to be a successful measure of insuring the long-term survival of the
panda? Explain your reasoning.
Part B: Impacts of Poaching
1. Does poaching have a noticeable effect on this panda population? Explain.
2. Is there any level of harvesting that the population can withstand? If so, what is it?
3. Given what you have learned about the giant panda and the threats facing it, what
would you recommend to those concerned with its long-term survival?
Exercise 2: Grizzly Bear and Habitat Restoration
1. How vulnerable are these grizzly bear populations to extinction?
2. Which of these three populations is the most vulnerable to extinction? Why?
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Environmental Science
Lab 6: Endangered Species
3. Does restoration of the habitat make a noticeable difference on the risk of
extinction? Does it affect the final abundance? Does it affect the risk of a 50%
decline? Be specific.
4. Suppose there is a large amount of pressure to harvest timber in these populations.
If harvesting reduces the fertility of the grizzly because of difficulty in finding
denning sites and disturbance caused by timber harvest, how will these populations
be affected?
5. Based on these models, do you believe that restoration of habitat that leads to
increases to fertility will be a good strategy for insuring the survival of all three
populations? What other strategies might be suitable? (Hint: What other parameters
could you “improve”?)
Exercise 3: Black-Footed Ferret and Reintroduction
1. How vulnerable is this newly reintroduced population to extinction if there are no
additional introductions (with the original vital rates)? What if the juvenile survival
was overestimated?
2. If you could restore and protect additional habitat the carrying capacity of this
population could be increased. What impact does increasing the carrying capacity
have on the original model?
3. How important is the parameter of juvenile survival to your predictions for this
population? Explain your reasoning.
4. How many total individual each year would you need to add to the population to
achieve a stable population size of 80 (with the reduced juvenile survival rate)? How
many total individuals would be introduced over the 50 years under this conservation
strategy?
5. Which is a more effective strategy for this population—increasing the carrying
capacity or adding individuals? Is this a realistic strategy for the long term? Discuss
some of the potential difficulties.
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