Combining dead recovery, auxiliary observations and robust design data to estimate demographic parameters from marked individuals

Abstract

Summary When estimating demographic parameters for wild populations, using multiple data sources can increase robustness through greater precision, reducing bias and permitting the estimation of otherwise confounded parameters. We present a method that combines recapture data from marked individuals, collected at a single study site, under a robust design framework, with dead recoveries and auxiliary resightings collected at any time and place. This model permits the joint modelling of survival, permanent and temporary emigration from the study area. We demonstrate that the usefulness of this model is compelling in the case of long‐lived species with substantial rates of temporary emigration, to mitigate bias in survival at the end of the time series and to permit conservation decisions based on more current information. We use the case of Florida manatees as an example. Our model can easily be extended to account for an arbitrary number of phenotypic states and account for state uncertainty. The increase in precision overall in vital rates, and the mitigation of bias in survival estimation in the final years of a time series, permits managers to base resource decisions on more robust and timely information. The model also provides the ability to adapt monitoring to changing conditions or specific management objectives, via dynamic allocation of effort to auxiliary resightings.