Estimating the survival of unobservable life stages for a declining frog with a complex life history

Demographic models enhance understanding of drivers population growth and inform conservation efforts to prevent declines extinction. For species with complex life histories, however, parameterizing demographic is challenging because some stages can be difficult study directly. Integrated (IPMs) empower researchers estimate vital rates for organisms that have cryptic or widely dispersing early by integrating multiple data sources. a stream-inhabiting frog (Rana boylii) declining through much its range in Oregon California, USA, we collected egg-mass counts capture–mark–recapture on adults from two populations California fit IPMs adult abundance the survival rate both marked unobserved stages. Estimates based long-term monitoring showed fluctuated greatly inter-annually but were stable at longer timescales (i.e., decades). Adult female during 5–6 yr periods was nearly equal each population. Survival R. boylii eggs subadult stage low average (0.002) highly variable among years depending post-oviposition stream flow. Population viability analysis has greatest proportional effect growth; egg tadpole stages, more malleable management interventions. example, simulations head-starting tadpoles, salvaging stranded masses, limiting aseasonal pulsed flows could dramatically reduce threat extirpation. This demonstrates value sources construct dynamics histories.