Abundance estimators and truth: Accounting for individual heterogeneity in wild house mice

We compared the actual abundance of 12 confined populations of wild house mice (Mus musculus) with closed population estimates based on mark-recapture data. Goodness-of-fit tests consistently detected individual heterogeneity in capture probability. Estimators designed to take such heterogeneity into account were expected to perform best, and generally did. However, of the 9 abundance estimators we considered, only Chao's modified moment estimator had no obvious bias and produced confidence intervals that always included the actual population size. The reliability of the 9 estimators and minimum number known alive (MNA), as indices of abundance, was quantified by (1) linear regression, and (2) calculating a Spearman rank correlation coefficient between the ranking obtained using the index and the true ranking.