Developing a monitoring protocol for a threatened species in a developing country: Lessons learned from monitoring the Togean Islands babirusa

•We used a power analysis to develop a monitoring protocol for the Togean babirusa.•Our protocol can detect a ≥ 20 % decline in occupancy of the species.•Areas with higher occupancy require lower sampling effort and should be prioritized.•Sampling effort for the monitoring can be adjusted following budget availability.•We present a budgeting scenario to perform the monitoring in developing countries. Monitoring is a critical step in evaluating the efficacy of conservation measures, and having an effective monitoring protocol can serve as a warning system for population decline. We performed a power analysis to develop a camera trap-based monitoring protocol to detect occupancy changes of the endangered Togean Islands babirusa (Babyrousa togeanensis) as a case study for a threatened species in a developing country. We divided our study sites, representing the entire distribution range of the species, into three areas following the species occupancy probability: high (0.8–1), medium (0.4–0.8), and low occupancy (0–0.4), and estimated the required sampling efforts to detect declines in occupancy in each area. Under a realistic sampling scenario (i.e., maximum 135 camera stations), our protocol is able to detect a ≥ 20 % occupancy decline in high occupancy areas and a ≥ 40 % decline in medium occupancy areas. The low occupancy area requires unrealistic sampling efforts to monitor changes in occupancy. We provide budgeting estimations for monitoring scenarios that are achievable in developing countries, as well as strategies to allocate limited funding. Furthermore, we derived some lessons from our study as guidelines for practitioners to develop and implement a cost-effective monitoring protocol for threatened species in developing countries, particularly by considering the species traits, management boundaries, priority areas, and budget constraints.