Abstract:
Increased environmental stochasticity due to climate change will intensify temporal variance in the life-history traits, and especially breeding probabilities, of long-lived iteroparous species. These changes may decrease individual fitness and population viability and are therefore important to monitor. In wild animal populations with imperfect individual detection, breeding probabilities are best estimated using capture-recapture methods. However, in many vertebrate species (e.g., amphibians, turtles, seabirds., non-breeders are unobservable because they are temporarily absent from breeding colonies. Although unobservable states can be used to model temporary emigration of non-breeders, there are disadvantages to having unobservable states in capture-recapture models. The best solution to deal with unobservable life-history states is therefore to eliminate them altogether. Here, we achieve this objective by fitting novel multi-event-robust design models which utilize information obtained from multiple surveys conducted throughout the year. We use this approach to estimate annual breeding probabilities of capital breeding female southern elephant seals (Mirounga leonina.. Conceptually, our approach parallels a multistate version of the Barker/robust design in that it combines robust design capture data collected during discrete breeding seasons with observations made at other times of the year. A substantial advantage of our approach is that the non-breeder state became “observable” when multiple data sources were analyzed together. This allowed us to test for the existence of state-dependent survival, and to estimate annual breeding transitions to and from the non-breeder state with greater precision compared to a multistate open robust design model. We used program E-SURGE (2.1.2. to fit the multi-event-robust design models, with uncertainty in breeding state assignment (breeder, non-breeder. being incorporated via a hidden Markov process. This flexible modelling approach can easily be adapted to suit sampling designs from numerous species which may be encountered during and outside of discrete breeding seasons. - Abstract as displayed in the - Abstract booklet. The presentation on the day may differ from the - Abstract.
