1. The Effects of Coyote Removal in Texas: A Case Study in Conservation Biology
National Center for Case Study Teaching in Science website;

2. Plains of West Texas
Shortgrass prairie
chaparral

3. Primary Producers: Grasses, herbaceous flowering plants (forbs)
Mesquite, yucca

4. Herbivores & Scavengers
Jackrabbits & cottontails
Ground squirrels
Rats (3 species)
Mice (7 species)
Ord’s Kangaroo Rat

5. Mesopredators
Badgers
Bobcats
Skunks
Grey fox

6. Top Predator
Coyote

7. What does this food web look like?
Ideas –
Draw on board

8. Part I Predator removal
The Nature Conservancy wants to determine the effects of coyote removal in West Texas
Your group has been asked to submit a proposal

9. Part I Questions What specific question do you intend to answer?
What type of experimental treatment and control will you use?
What variables do you intend to monitor?

10. Part II Congratulations! Your proposal has been funded.
Experimental design:
Four, 5,000 ha sites
2 controls, 2 treatments
Similar ecological communities represented

11. Part II – Experimental Design
Figure 1.  Location of experimental sites in West Texas. Sites 1 and 2 were the control sites. Coyotes were removed from sites 3 and 4 and from a 5-km border (figure from Henke and Bryant 1999, used with permission).

12. Part II-Experimental Design
Four, 5,000 ha sites
2 controls, 2 treatments
All coyotes removed from treatment sites & 5 km border
No manipulation of control sites
Animal community monitored on all sites:
1 year prior to treatment
2 years following coyote removal

13. Part II
Question
Make two predictions concerning the effects of coyote removal on the fauna of West Texas.

14. Part III - Mesopredators
Mesopredator populations monitored for 3 years
Total abundance of badgers, bobcats, skunk and fox found on treatment and control sites plotted each year
Use these data to interpret the impact of coyote removal on the community of small mammalian predators

15. Part III - Mesopredators
Figure 2.  Relative abundance of mammalian mesopredators in the experimental sites before and after treatment. Error Bars represent one standard error (figure modified from Henke and Bryant 1999, used with permission).

16. Part III - Mesopredators
Questions
What effect does coyote removal have on the mesopredator populations?
Predict what might have happened to the rodent populations as a result of changes in the mesopredator populations.

17. Part IV – Rodent Population Size
You decide to analyze data on rodent population size next
As a measure of population size, you compare rodent biomass in grams per hectare in treatment vs. control areas over 3 years

18. Part IV – Rodent Population Size
Figure 3.  Biomass of rodents in the experimental sites before and after coyotes were removed from the treatment sites. Error Bars represent one standard error (figure modified from Henke and Bryant 1999, used with permission).

19. Part IV – Rodent Population Size
Questions
What do you think is the primary factor controlling rodent population growth?
Given the changes in population size, what other changes might you expect in the rodent community?

20. Part V – Rodent Diversity
Population size of individual rodent species shows Ord’s kangaroo rat doing very well in treatment areas
Examine the data:

21. Part V – Rodent Diversity
Figure 4.  Diversity of rodents in the experimental sites before and after coyotes were removed from the treatment sites. Rodent diversity was estimated using Simpson's Index. Error Bars represent one standard error (figure modified from Henke and Bryant 1999, used with permission).

22. Part V – Rodent Diversity
Questions
In one sentence summarize the meaning of the graph shown in Figure 4.
How does the competitive success of Ord's kangaroo rat change in the absence of coyotes?
What term could be used to describe the role of the coyote in this community?
Propose one possible cause for the decline in rodent diversity in the control areas after treatment begins.
In your report to The Nature Conservancy, how will you summarize the impact of coyote removal in this community?

23. Business Letter Format

24. References
Henke, S.E., and F.C. Bryant Effects of coyote removal on the faunal community in Western Texas. Journal of Wildlife Management 63:
Carroll, M The effects of coyote removal in Texas: A case study in conservation biology. National Center for Case Study Teaching in Science website: ; site visited 9/06