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How do you estimate animals you never saw?

Counting every animal in a population can be impractical. In a simple mark-and-recapture model, the proportion of previously marked animals in a later sample offers a clue to the total. The estimate depends on assumptions about mixing, survival, movement, and capture, rather than the formula alone.

8–10 min

Questions you could explore

  • What happens if marked animals become harder to catch?
  • Why would very few recaptures make the estimate fragile?

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