Known unknowns in an imperfect world: incorporating uncertainty in recruitment estimates using multi-event capture-recapture models

• Published in: Ecology and Evolution
• Main Authors: Desprez, M, McMahon, CR, Hindell, MA, Harcourt, R, Gimenez, O
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley-Blackwell 2013
• Subjects: Biological Sciences; Ecology; Marine and Estuarine Ecology (incl. Marine Ichthyology); Elephant Seals; Southern Elephant Seals
• Online Access: https://doi.org/10.1002/ece3.846; http://ecite.utas.edu.au/89025

Studying the demography of wild animals remains challenging as several of thecritical parts of their life history may be difficult to observe in the field. In particular,determining with certainty when an individual breeds for the first timeis not always obvious. This can be problematic because uncertainty about thetransition from a prebreeder to a breeder state recruitment leads to uncertaintyin vital rate estimates and in turn in population projection models. Toavoid this issue, the common practice is to discard imperfect data from theanalyses. However, this practice can generate a bias in vital rate estimates ifuncertainty is related to a specific component of the population and reducesthe sample size of the dataset and consequently the statistical power to detecteffects of biological interest. Here, we compared the demographic parametersassessed from a standard multistate capturerecapture approach to the estimatesobtained from the newly developed multi-event framework that specificallyaccounts for uncertainty in state assessment. Using a comprehensive longitudinaldataset on southern elephant seals, we demonstrated that the multi-eventmodel enabled us to use all the data collected (6639 capturerecapture historiesvs. 4179 with the multistate model) by accounting for uncertainty in breedingstates, thereby increasing the precision and accuracy of the demographic parameterestimates. The multi-event model allowed us to incorporate imperfect datainto demographic analyses. The gain in precision obtained has important implicationsin the conservation and management of species because limiting uncertaintyaround vital rates will permit predicting population viability with greateraccuracy.