1. Population Dynamics Ms. Byers and Ms. Jacobs

2. Why Estimate Population Size? To compare populations in different areas To assess the health of wildlife –Take action if required To answer questions about what humans are doing to wildlife

3. Sampling Methods

4. Marking Methods Bird Banding Ear Tagging Mammal Tagging

5. More Marking Methods Pit Tagging Tattooing Branding Fluorescent markers

6. Toe-Clipping

7. Mark-Recapture A method used in ecology to estimate population size –Use it when you cannot detect all individuals in a population Other Names –capture-recapture –capture-mark-recapture –mark-release-recapture

8. Mark-Recapture Trap a sample of live animals on site Mark the animals Release the animals unharmed Allow time for the population to redistribute Return to site, capture another sample Count recaptures Do math

9. The Lincon-Peterson Index N = Estimate of total population M = # of animals marked on first visit C = Total # of animals caught on second visit R = # of marked animals caught on second visit R/M = C/N N = MC/R

10. Agriculture Impacts When a forest becomes a farm, the landscape is permanently altered Can wildlife survive in this new habitat? To address these questions scientists compare populations from forest and agricultural landscapes

11. Amphibians and Agriculture Would you expect to find larger amphibian populations in a pond on a farm (open field) or in a forest? Compare amphibian abundance between the two habitat types Sample amphibian populations on farmland and forest sites

12. Four Field Sites - 2 Forest Sites - 2 Farm Sites Sample amphibians and estimate populations at each site

13. Mark-Recapture Assumptions Closed population Tags stay on Marked and unmarked animals have the same probability of being captured Marked and unmarked individuals randomly mix between samples

14. Limitations Must be able to trap sufficient animals Must be able to sample randomly

15. Results Was amphibian abundance higher at farm or forest sites? How can you explain your results