BIOL 3370L capture-recapture method

BIOL 3370L capture-recapture method 



 In a Word document:

  1. Use the spreadsheet provided and the formula below to estimate three grasshopper population sizes.


Calculate three population sizes (3 Ns), either for one color (across all lab sections) or for one lab section (all three colors) AND provide the average of the three population sizes.

Indicate how you arrived at each estimate, that is, for each estimate, indicate the numbers used for “M”, “C”, and “R”.

Clearly indicate the average population size.

  1. In the same word document, address each of the assumptions involved in using this method (indicated below) to calculate population size and explain whether you think each assumption was met, and why or why not. Each assumption thus merits a small paragraph of text.


The capture-recapture method rests on several assumptions:

All individuals in the population have an equal chance of being captured.

  1. There is no change in the ratio of marked to unmarked animals between capture times. This means that there have been no significant additions of unmarked individuals to the population via births or immigration and that decreases in the population (death or emigration) have affected marked and unmarked individuals proportionally.
  2. Marked individuals distribute themselves in the population homogeneously after being released.
  3. Capturing an organism does not affect its chances of being recaptured.
  4. Marks are not lost or overlooked.