1. Define the terms proximate cause and ultimate cause.
2. What was the ultimate cause of the pelican's decline?
3. What was the proximate cause of the pelican's decline?
4. Describe what DDT does to pelican eggs?
5. What two things does a biologist look for when studying the reasons for population decline
6. What is the difference between direct and indirect threats?
7. List 3 examples of indirect threats.
8. List 3 examples of direct threats.
9. Describe the relationship between threats and ultimate causes.
10. Define and give examples for each type of unpredictability.
11. Why are unpredictable events so dangerous for small populations?
12. Define positive feedback loop.
13. Define carrying capacity.
14. Explain how carrying capacity is an example of a negative feedback loop.
15. Describe how negative and positive feedback loops may function in the squirrel population

back to Endangered Species Pamphlets

• U. S. Department of the Interior Wildlife Fact Sheets
  http://species.fws.gov/
  • search for species by common or scientific name
  • photographs and current status
• U. S. Department of the Interior, Endangered Species Program
  http://endangered.fws.gov/
  • search for species by common or scientific name
  • photogaphs and current status
• National Audobon Society
• http://www.audubon.org
  • primarily dedicated to birds, but also to conservation of species and habitats.
  • Click on the link to
    • National Wildlife Refuge Campaign
  • http://www.audubon.org/campaign/refuge/
• National Wildlife Federation
• http://www.nwf.org/