Evaluating population recovery for sea turtles under nesting beach protection while accounting for nesting behaviours and changes in availability

摘要: Summary 1. Sea turtles and sea birds generally have high conservation importance world-wide are often difficult to survey except when present on nesting grounds. Consequently, many such surveys tag individuals use tag-resighting models estimate population size assess anthropogenic impacts. However, the conventional Cormac–Jolly–Seber (CJS) model is problematic for these species three reasons: return areas in alternating years because of energetic costs nesting, estimated detectability confounds changes efficiency with availability surveyed beach, loss confounded mortality. 2. We develop a robust design that uses higher-order Markovian transitions approximate skip-nesting behaviours incorporates multiple observations each individual (the probability returning area rather than alternative areas). We time-varying effects using flexible spline method demonstrate data leatherback Dermochelys coriacea loggerhead Caretta caretta South Africa. 3. The apparent lack recovery after implementing beach protection, as observed nest count data, likely be due declining caused by decreased during (e.g. habitat expansion). By contrast, approximately constant stable abundance since 1970s. 4. We find increased fishing effort has no explanatory power regarding survival either species. 5. Synthesis applications. Based study results, we recommend future programmes accompanied periodically beyond regularly monitored evaluate evidence range expansion. identification expansion historical only possible model-based inference methods presented this study.