Estimating temporary migration using the robust design.

*(English)* Zbl 0881.62126
Summary: One of the basic assumptions central to the analysis of capture-recapture experiments is that all marked animals remain in the population under study for the duration of the sampling, or if they migrate out of the population they do so permanently. {\it K. P. Burnham} [in J.-D. Lebreton and P. M. North (eds.), Marked Individuals in the Study of Bird Populations, 199-213 (1993)], {\it W. L. Kendall} and {\it J. D. Nichols} [J. Appl. Stat. 22, 751-762 (1995)], and {\it W. L. Kendall}, {\it J. D. Nichols} and {\it J. E. Hines} (in press) showed that completely random temporary emigration influences only estimates of the probability of capture, these now estimating the product of the temporary emigration rate and the conditional probability of capture given the animal remains in the population. Estimates of abundance or survival that refer to the entire population, including the temporary emigrants, remain unaffected. {\it W. L. Kendall} et al. (in press) further showed that {\it K. H. Pollock}’s [J. Wildlife Manage 46, 757-760 (1982)] robust design could be used to estimate the temporary emigration rate when the population ws assumed closed during the secondary samples.
We generalize this result to allow animals to enter and leave the population during the secondary samples. We apply the results to a study of Grey Seals and perform simulation experiments to assess the robustness of our estimator to errors in field identification of brands and other violations of our assumptions.

##### MSC:

62P10 | Applications of statistics to biology and medical sciences |