Estimating Population Size

Estimating population size

Lab Protocol


Extension:
Part A
 Repeat your Capture, Mark and recapture, but this time fill the trap to the 40 ml line. That is, you will be doubling your sampling effort.

Repeat your Capture, Mark and recapture, but this time fill the trap to the 60 ml line. That is, you will be doubling your sampling effort..

 III. Results In a graph, compare the entire class's mean estimates for population size for each of the three sampling efforts.

 What happens to each of the parameters listed below when sampling effort is first doubled (10 ml vs. 20 ml) and then increased again by 50% (20 ml vs. 30 ml)?

Mean of the estimates at each 'Effort'

Standard error of the mean of the estimates

Range of estimates Assuming cost is an issue, which of the three sample sizes would be the best ? (In the sampling of actual wildlife, cost usually is an issue. It can be expensive and time-consuming and laborintensive to sample wild populations. Getting accurate results without consuming to many resources [time, money, possible harassment of animal population] is a worthy goal. )

 IV. Conclusion 1. Evaluate how well you were able to satisfy each of the assumptions of the mark-recapture technique. 2. If migration occurred in a natural population being studied, how would this influence the reliability of your estimate of population size determined using the mark-and-recapture technique? Would your population estimate be too high or too low, or would you not be able to predict how your estimate would be biased? (Remember: migration consists of both immigration and emigration. 3. Discuss the kind of bias you would expect to be generated in the estimate of population size (and/or the standard error) if each of the remaining assumptions (2, 3, and 4) were violated. (For example: If Assumption 2 is not met, would it cause the size of the population to be overestimated? underestimated? Or have no effect? ) Note that it is possible that violating several different individual assumptions may have the same effects.



Part B

1. Make a box of a known population. (Total number of individuals should be above 500 and below 5000)
2. Label Box with Lab period and Table #
3. Turn in an index card with the population description to Mr. Smirk.
4. Get another prepared box and using the techniques developed create a description of the population. Include in your description your confidence in the estimations you have made.
5. Get answer card from Mr. Smirk and calculate your percent error. Describe what factors may have led to your error and how they influenced your results.

Range of estimates Assuming cost is an issue, which of the three sample sizes would be the best ? (In the sampling of actual wildlife, cost usually is an issue. It can be expensive and time-consuming and labor intensive to sample wild populations. Getting accurate results without consuming to many resources [time, money, possible harassment of animal population] is a worthy goal. )

 IV. Conclusion
1. Evaluate how well you were able to satisfy each of the assumptions of the mark-recapture technique.
2. If migration occurred in a natural population being studied, how would this influence the reliability of your estimate of population size determined using the mark-and-recapture technique?
Would your population estimate be too high or too low, or would you not be able to predict how your estimate would be biased? (Remember: migration consists of both immigration and emigration.
3. Discuss the kind of bias you would expect to be generated in the estimate of population size (and/or the standard error) if each of the remaining assumptions  were violated. (For example: If Assumption 2 is not met, would it cause the size of the population to be overestimated? underestimated? Or have no effect? ) Note that it is possible that violating several different individual assumptions may have the same effects.