Xuebo Xi, Yuansi He, Siyi Zeng, S M Yang, Zhuo Pan, Jia Zheng, Daiping Wang
Abstract Reintroduction programs are critical for restoring threatened species, yet quantitative evaluations integrating vital rates across the full life cycle remain limited. Nipponia nippon (Asian Crested Ibis), once nearly extinct, has been the focus of intensive conservation efforts, including reintroduction into its historical range in central China. Here, we evaluate the success of a reintroduced N. nippon population by integrating multi-year field monitoring with population dynamics modeling. We conducted a multi-year demographic study (2023–2025) in Dongzhai National Nature Reserve, China. Based on monitoring of breeding attempts (n = 176) and GPS telemetry (n = 74 tags; maximum tracking duration 4 years), we quantified reproductive output and stage-specific mortality across 6 life stages. Mean clutch size was 3.24 ± 0.08, and breeding pairs reared an average of 1.31 ± 0.12 fledglings per year. Breeding failure during incubation was 32.5% (n = 425 eggs), largely due to egg infertility and nest desertion. Failure was highest during chick provisioning (34.1%, n = 287 chicks), while mortality was highest during the fledgling stage (38.6%, n = 63 individuals), mainly due to predation and starvation. In contrast, breeding failure during nest building was relatively low (9.1%), while mortality during the subadult and adult stages was 9.8% and 21.3%, respectively. A stage-structured matrix model projected sustained population growth under density-independent conditions (r = 0.046, 95% CI: 0.034–0.057), with the population projected to increase from ∼500 to 5,286 individuals (95% CI: 2,772–8,817) over 50 years. Incorporating density dependence reduced growth but did not reverse the positive trajectory. Sensitivity analyses indicated that population growth was most strongly influenced by adult survival, highlighting the importance of maintaining high adult survival to support long-term population persistence.