Macaca nigra
In addition to contributing valuable information on the distribution and status of the species, our study facilitates the design of a targeted monitoring protocol, which we define as 90 sites surveyed with camera traps for 90 days (18 × 5-day occasions) per season.Testing the power of this de- sign under simulation,we found itwould be possible to detect an annual change in occupancy of 10%(a declinewe consider sufficiently severe to initiate a conservation intervention), with 80% certainty if implemented over 3 seasons. By demonstrat- ing the robustness of our suggested protocol in meeting the objectives of such a monitoring programme, researchers can be confident in investing resources in its long-term imple- mentation (Yoccoz et al., 2001;Legg&Nagy, 2006). Meaningful monitoring studies, especially at large spa-
FIG. 4 Total survey effort required (sites × repeats) (a), and total number of unique camera sites required (b) to achieve a given precision in the occupancy estimate as a function of the number of repeats required per camera. Repeats are represented by months; a single repetition has a duration of 5 days and 1 month is therefore six repeats. Curves were created based on the averaged model (p = 0.28 and ψ = 0.66) and on the asymptotic properties of the maximum likelihood estimates. The curves correspond to different standard errors in the occupancy estimate.
area of occupancy of 2,101 km2 and an extent of occur- rence of 7,810 km2. The Critically Endangered status of M. nigra was a result of suspected severe population de- clines. As we only provide a baseline, using new survey methodology, we can neither support nor refute this. However, with a greater range than previously thought, our findings may influence the threatened status of the species and therefore have implications for any future review of the species’ Red List status. With this in mind, we caution that the species remains highly threatened, particularly outside protected areas, and emphasize the need for standardized monitoring that follows the proto- col we recommend. This will identify trends in the popu- lation and lead to a clearer picture of the species’ status. In the meantime, we stress the need for increased conser- vation management in the landscapes identified as im- portant (Supplementary Table 3).
tial scales, are considerable investments of limited conser- vation resources. Procurement of the cameras required for a study such as this constitutes a high cost, which must be justified given the availability of other presence/absence survey methods such as line transect surveys. We were able to use data collected during this study to conduct a basic feasibility comparison between the two methods and found that the cost efficiency of camera traps was far greater than that of a more labour intensive transect method, even after considering the cost of cameras (Sup- plementary Table 4). As such, although initial costs are high, camera traps may provide a cheaper alternative for monitoring certain species. In conclusion, our study provides a robust baseline for
M. nigra occupancy and, through simulation, indicates how the monitoring of a generally elusive and Critically Endangered primate through camera trapping could be feasible at a landscape level. We emphasize the necessity of such amonitoring approach for understanding popula- tion responses to ecological and anthropogenic factors and hence informing conservation efforts. The baseline we report forms the basis on which temporal trends in M. nigra occupancy could be detected, and the study design we suggest provides a robust means of detecting potential declines within a suitable timeframe. In demon- strating the potential of camera-trap data analysed in an occupancy framework to monitor M. nigra,weadd to a growing body of literature that promotes occupancy as a fea- sible alternative to abundance-based metrics for monitoring wild primates (Guillera-Arroita et al., 2010; Keane et al., 2012; Gerber et al., 2014; Rovero et al., 2015).
Acknowledgements We thank the Ministry of Science and Technology for permission to conduct this research in Indonesia; Bogani Nani Wartabone National Park management authority for research permission; BKSDA North Sulawesi, in particular Pak Yakub Ambagau, for support of our research; our field assistants Nicodemus Malir, Hanisa Silayar, Fandy Pongantung, Adha Yakseb, Omega Judistira, Idham Pohi, Muhamad Ihwan, Sukrisno and Luciano Gawina; Graeme Gillespie for providing advice during the conception of this project; and two anonymous reviewers for their
Oryx, 2020, 54(6), 784–793 © The Author(s), 2020. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/S0030605319000851
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