Estimation of Time-Specific Survival Rates from Tag-Resighting Samples: A Generalization of the Jolly-Seber Model

The resighting rather than recapturing of individuals that were initially captured, tagged and returned to a population offers a means of circum-venting the often traumatic and sometimes fatal effect of repeated cap-ture and handling of wild animals in a tag-recapture study. The behavioral effect of initial capture and tagging, however, must often be accounted for in the model. If sighting records are restricted to tagged individuals, with no attempt at estimating a tagged/untagged ratio in the population, the model requirements are simplified to include only the modeling of mortality among tagged individuals and to exclude recruitment parameters in the unobserved, untagged portion of the population. Short-term capture/ tagging effects of specified duration (i.e., lasting for only one time period) are incorporated into the proposed model, and their biasing effects thereby eliminated from estimates of time-specific survival rates. Stan-dard error formulas and tests of the model are provided in this generaliza-tion of the Jolly-Seber method of tag-recapture analysis.