1. Estimating Populations
Mark and Recapture:
Estimating Populations

2. The mark and recapture method is based on the assumption that if a sample is RANDOMLY collected and marked, then ALLOWED TO ASSIMILATE back into the population and then a sample is RANDOMLY collected again- that the fraction of the population that is marked in the second capture is proportional to the fraction of the original capture compared to the whole population.
Example: If one third the recapture was marked, then the initial capture is assumed to be equal to one third of the entire population.

3. M m --- = --- N n M = marked in 1st capture
--- = ---
N n
M = marked in 1st capture
m = recaptured (marked in 2nd capture)
n = number in second recapture
N = number in total population

4. The method of marking the animals must not increase or decrease the likelihood that they are recaptured.
Video of a tagging method that was not successful:
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