Managers of threatened species in remote protected areas play a pivotal role in shaping the outcomes of management and conservation programmes. The island of Java supports the last remaining population of the Javan rhinoceros Rhinoceros sondaicus, a Critically Endangered megaherbivore with only 72 individuals persisting in the wild, in Ujung Kulon National Park. Substantial resources are being invested to manage the Javan rhinoceros and it is difficult to monitor it in the rainforest to assess whether management actions have been successful. Insights from frontline staff into the outcomes of past conservation actions and the future actions required may be key to enhancing the outcomes of conservation actions for threatened species. To study the perceptions of frontline staff towards the conservation of the Javan rhinoceros, management actions and their outcomes, we surveyed all 36-frontline staff in Ujung Kulon National Park. Although staff perceptions of conservation outcomes were generally positive, they noted key anthropogenic threats and challenges to rhinoceros protection inherent to the survival of the last Javan rhinoceros population. Staff identified increased threat of disease transfer from domestic stock to the rhinoceros, in spite of protective fencing, and the combined effects of illegal firewood collection and agricultural encroachment on rhinoceros habitat. Systematically recording and incorporating the perceptions of frontline staff in remote and often inaccessible protected areas can help identify important areas for future conservation and threat mitigation that can facilitate better protection for the Javan rhinoceros and other iconic species.