Chapter 9 Assessing Threats and Choosing Conservation Actions

Discussion Questions

1. Draw a life-cycle diagram (as described in Chapter 8) corresponding to the demographic matrix provided as equation 9.1. Use the matrix and your diagram to answer these questions: What percentage of large juveniles die each year? How likely is an individual that is currently a large juvenile to become a subadult in either the upcoming year or the year after that?
2. Imagine that you are considering two alternative management scenarios for an endangered species. One scenario would improve the survival of the subadult class of animals; the other would improve the reproductive output of the oldest size class. Describe how you might use a demographic matrix model to determine which action would be more effective.
3. What are the pros and cons of using a demographic matrix model to understand the relative effectiveness of alternative management actions?
4. Imagine a species of coral reef fish that is threatened by both overfishing and pollution. Design an observational study (or possibly a pair of studies) that you could use to understand the relative importance of these two threats. Be sure to specify whether you would use a control-impact, BACI, or regression approach. Describe how your study would deal with any potentially confounding variables.
5. Imagine that you are living in the United States in the 1960s and suspect that DDT may be contributing to the decline of bald eagles. Manipulative experiments are out of the question because the number of bald eagles is low and this species is protected as the nation's symbol. Suppose you have a time-series of data on hatching success that covers a period before and after the start of DDT usage in two areas—one where DDT is used extensively and another where it is not used. What is the argument against using the data from the DDT-affected area to do a simple before-after comparison? Similarly, what is the argument against using only the "after" data to compare the two areas? Now construct a graph with hypothesized data corresponding to a BACI analysis (similar to the graphs used in Levin and Tolimieri's salmon study) that shows a strong effect of DDT on hatching success. HINT: The vertical axis should show the difference in hatching rates between the two sites (high-DDT site versus no-DDT site).

Group Projects

• Select three species from the IUCN Red List, excluding any for which no threats are listed. For each of these three species, read the underlying assessment documents, paying particular attention to the quality of data used to determine the major threats to the species. Did the assessment rely solely on expert opinion? If threat analyses are cited, do they appear to have been manipulative experiments, observational studies, or modeling exercises? What is your overall assessment of the quality of evidence used to identify key threats to each species?
  
  
• Search the ReefBase database to compare the threats in two different global regions (Africa, Pacific, Asia, Americas, Middle East, Australia, Coral Triangle). Discuss the extent to which the coral reefs in these two areas face similar versus distinctive threats. What does this suggest regarding a global strategy for coral conservation?

Useful Websites

• Compass Resource Management offers examples and practical guidance for how to use structured decision making in conservation. http://www.structureddecisionmaking.org/


• Global Coral Disease Database is a compilation of coral disease records and information hosted by the UNEP World Conservation Monitoring Centre. http://coraldisease.org/


• IUCN Red List of Threatened Species can be searched by risk category, taxonomic group, geographic region, habitat types, threat types, etc. http://www.iucnredlist.org


• ReefBase provides a global database (http://www.reefbase.org/global_database) documenting the locations, status, threats, and management of coral reefs. An on-line library and photos are also available through this site. http://www.reefbase.org


• State of the Salmon offers information about salmon and their habitats for the entire North Pacific. Data and maps document the distribution, abundance, and threats to each of the Pacific salmon species. http://www.stateofthesalmon.org


• State of the World's Sea Turtles (SWOT) provides information on the status of sea turtle populations and an interactive map of sea turtle nesting beach data. http://seaturtlestatus.org


• U.S. Fish and Wildlife Service Endangered Species Program offers electronic access to all recovery plans that have been finalized or revised since 1989. http://www.fws.gov/endangered/species/recovery-plans.html

Suggested Readings for In-class Discussion

• Carwardine J, O’Connor T, Legge S, Mackey B, Possingham HP, Martin TG (2012) Prioritizing threat management for biodiversity conservation. Conserv Lett 5: 196-204. http://onlinelibrary.wiley.com/doi/10.1111/j.1755-263X.2012.00228.x/full (open access)
  
  
• McDonald-Madden E, Game ET (2013) Infusing structure into environmental management decisions. Trends Ecol Evol 28: 258-259.
  
  
• Peery MZ, Henry RW (2010) Recovering marbled murrelets via corvid management: A population viability analysis approach. Biol Conserv 143: 2414-2424.
  
  
• Wilsey CB, Lawler JJ, Cimprich D, Schumaker NH (2014) Dependence of the endangered black-capped vireo on sustained cowbird management. Conserv Biol 28: 561-571.