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#capture-recapture

2 public questions tagged with this topic.

What is the correct combination for estimating population using mark-recapture?

A valid mark–recapture estimate requires information about the first marked sample, the size of a later capture, and how many marked individuals appear in that later capture. It also requires assumptions: marks are retained and recognized, marking does not alter survival or catchability, marked organisms mix into the population, sampling probabilities are comparable, and the population is effectively closed during the study interval. These conditions justify M/N ≈ R/C and hence N ≈ MC/R. The row refers to statements labeled A–E, but those statements are absent from the workbook’s question text

Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 9

From a field, 80 rats are marked and released. A month later, 100 rats are captured, 20 are marked. Estimate population

The Lincoln–Petersen estimator uses N ≈ MC/R. The initial marked release is M = 80 rats, the second capture contains C = 100 rats, and R = 20 of those are marked. Therefore N = 80 × 100/20 = 400 rats. Since marked animals constitute one-fifth of the recapture sample, the marked cohort is inferred to represent one-fifth of the whole population; five times 80 gives the same estimate. The method assumes that the population is effectively closed during the month, all animals have equal capture probability, marks remain visible and do not affect survival or behavior, and marked rats mix randomly wi

Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 9