Intense trapping of the critically endangered Yellow-crested Cockatoo (Cacatua sulphurea) for the international pet trade has devastated its populations across Indonesia such that populations of >100 individuals remain at only a handful of sites. We combined distance sampling with density surface modeling (DSM) to predict local densities and estimate total population size for one of these areas, Komodo Island, part of Komodo National Park (KNP) in Indonesia. We modeled local density based on topography (topographic wetness index) and habitat types (percentage of palm savanna and deciduous monsoon forest). Our population estimate of 1,113 (95% CI: 587–2,109) individuals on Komodo Island was considerably larger than previous conservative estimates. Our density surface maps showed cockatoos to be absent over much of the island, but present at high densities in wooded valleys. Coincidence between our DSM and a set of independent cockatoo observations was high (93%). Standardized annual counts by KNP staff in selected areas of the island showed increases in cockatoo records from <400 in 2011 to ~650 in 2017. Taken together, our results indicate that KNP, alongside and indeed because of preserving its iconic Komodo dragons (Varanus komodoensis), is succeeding in protecting a significant population of Indonesia’s rarest cockatoo species. To our knowledge this is the first time DSM has been applied to a critically endangered species. Our findings highlight the potential of DSM for locating abundance hotspots, identifying habitat associations, and estimating global population size in a range of threatened taxa, especially if independent datasets can be used to validate model predictions.

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A challenge with species that have disappeared from most of their range is to identify the correlates of local persistence. With species decimated by trade, site‐specific trapping risk is hard to capture by remotely accessed predictors. The recently split yellow‐crested cockatoo Cacatua sulphurea and citron‐crested cockatoo C. citrinocristata have undergone catastrophic declines due to habitat loss and especially trapping, and are now extinct in much of their former range across Indonesia. Of 144 sites on 30 islands known to contain the species in 1950, only 76 on 27 islands did so in 2017–2019, with many of the other 68 experiencing extinctions between 1985 and 2000. We compared socio‐ecological conditions such as forest cover and loss, human population density and infrastructure, and protected area status between the occupied and unoccupied sites, using ‘random forests’ within decreasing time intervals 1950–2015. Populations on Sulawesi and West Nusa Tenggara were more likely to become extinct than those on Sumba, Timor‐Leste and small remote islands. Sites retaining cockatoos had high proportions of tree cover, low road density and low human densities. The relative importance of these factors changed little over time, but road density and human density became respectively more and less important in recent years. The examination of local conditions at ‘false negative’ sites (where cockatoos survived contrary to model predictions) showed that, particularly in recent years, cockatoo survival has been promoted by site‐specific protection due to traditional beliefs, NGO activities, dedicated individual residents and local topographic barriers. Some of these local influences add complexity to the task of conserving cockatoo strongholds, but also offer exciting possibilities for low‐cost conservation prescriptions tailored to individual sites. Studies combining field and remotely sensed data, and examining false negative sites for beneficial location‐specific conditions, have broad application for the conservation of taxa with once‐large ranges.

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Mangrove forest in Kao Village, North Halmahera Regency, North Maluku Province, is a Key Biodiversity Area. Since 2017, the community has been protecting mangrove forests through Kao Village Regulation No.03/2007. In 2020, through the collaboration between stakeholders from universities, NGOs and the government, the Kao mangrove forest area of 300.92 Ha was designated as an Essential Ecosystem Area (EEA) based on the North Halmahera Regent Decree No.078/102/HU/2020. This study describes the biodiversity and the community-based conservation through stakeholder collaboration in the EEA of Kao. The study found that there are 13 mangrove species and 56 bird species, of which 10 are protected species. In 2020, the community has built a mangrove nursery and rehabilitated 8 ha of degraded mangrove forest with the participation of about 70 people. Since the establishment of EEA, the community has stopped hunting for eggs of the endemic moluccan scrubfowl (Eulipoa wallacei) and is trying to increase its population through semi-natural hatching on the beach. The community has also learned to use non-timber mangrove forest products and ecotourism through the support of stakeholders.