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Habitat degradation and hunting have caused the widespread loss of larger vertebrate species (defaunation) from tropical biodiversity hotspots. However, these defaunation drivers impact vertebrate biodiversity in different ways and, therefore, require different conservation interventions. We conducted landscape-scale camera-trap surveys across six study sites in Southeast Asia to assess how moderate degradation and intensive, indiscriminate hunting differentially impact tropical terrestrial mammals and birds. We found that functional extinction rates were higher in hunted compared to degraded sites. Species found in both sites had lower occupancies in the hunted sites. Canopy closure was the main predictor of occurrence in the degraded sites, while village density primarily influenced occurrence in the hunted sites. Our findings suggest that intensive, indiscriminate hunting may be a more immediate threat than moderate habitat degradation for tropical faunal communities, and that conservation stakeholders should focus as much on overhunting as on habitat conservation to address the defaunation crisis.

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Conservation of Indochinese primates is hampered by a lack of knowledge of species ecology, habitat preferences and, locally, distribution. Predictive distribution and habitat suitability models, using predictors known to affect the distribution of similar species elsewhere, may, therefore be of great benefit to conservationists within the region. Yellow-cheeked crested gibbon Nomascus gabriellae is an IUCN-listed endangered primate distributed east of the Mekong River in Cambodia, southern Vietnam, and possibly southern Lao PDR. Within Cambodia, yellow-cheeked crested gibbon are naturally restricted to evergreen forest fragments within a landscape matrix of deciduous dipterocarp and semievergreen forests. During the 2008 dry season, auditory surveys for yellow-cheeked crested gibbon were conducted within Phnom Prich Wildlife Sanctuary, Mondulkiri province, Cambodia. Predictive distribution models, in which variables were included at the scale at which they best explained gibbon occurrence (multi-grain models), were constructed to examine the species' habitat associations and tolerance of habitat fragmentation within the wildlife sanctuary. Gibbon occupancy ( j) was higher in evergreen (0.43 AE 0.26-0.62) than in semi-evergreen forest (0.21 AE 0.09-0.4), with gibbon presence constrained by a critical amount of evergreen forest within 5 km radius of listening posts. Three patches of optimal habitat within Phnom Prich Wildlife Sanctuary were identified. These, and connecting habitats, should be the target of increased enforcement effort to limit hunting and habitat conversion. Similar multi-grain models are likely to be valuable for conservationists within mosaic habitats as they can facilitate identification of the minimum suitable fragment size for species of conservation concern.

With less than 3200 wild tigers in 2010, the heads of 13 tiger-range countries committed to doubling the global population of wild tigers by 2022. This goal represents the highest level of ambition and commitment required to turn the tide for tigers in the wild. Yet, ensuring efficient and targeted implementation of conservation actions alongside systematic monitoring of progress towards this goal requires that we set site-specific recovery targets and timelines that are ecologically realistic. In this study, we assess the recovery potential of 18 sites identified under WWF’s Tigers Alive Initiative. We delineated recovery systems comprising a source, recovery site, and support region, which need to be managed synergistically to meet these targets. By using the best available data on tiger and prey numbers, and adapting existing species recovery frameworks, we show that these sites, which currently support 165 (118–277) tigers, have the potential to harbour 585 (454–739) individuals. This would constitute a 15% increase in the global population and represent over a three-fold increase within these specific sites, on an average. However, it may not be realistic to achieve this target by 2022, since tiger recovery in 15 of these 18 sites is contingent on the initial recovery of prey populations, which is a slow process. We conclude that while sustained conservation efforts can yield significant recoveries, it is critical that we commit our resources to achieving the biologically realistic targets for these sites even if the timelines are extended.

The Bengal Florican is a 'Critically Endangered' bustard (Otididae) restricted to India, Nepal and southern Indochina. Fewer than 500 birds are estimated to remain in the Indian subcontinent, whilst the Indochinese breeding population is primarily restricted to grasslands surrounding the Tonle Sap lake, Cambodia. We conducted the first comprehensive breeding season survey of Bengal Florican within the Tonle Sap region (19,500 km2). During 2005/06 and 2006/07 we systematically sampled 1-km squares for territorial males. Bengal Florican were detected within 90 1-km squares at a mean density of 0.34 males km-2 which, accounting for unequal survey effort across grassland blocks, provides a mean estimate of 0.2 males km-2. Based on 2005 habitat extent, the estimated Tonle Sap population is 416 adult males (333 - 502 ± 95% CI), more than half of them in Kompong Thom province. Tonle Sap grasslands are rapidly being lost due to intensification of rice cultivation and, based on satellite images, we document declines of 28% grassland cover within 10 grassland blocks between January 2005 and March 2007. Based on mean 2005 population densities the remaining grassland may support as few as 294 adult male florican, a decline of 30% since 2005. In response to these habitat declines almost 350 km2 of grassland have been designated as protected areas, set aside for biodiversity and local livelihoods. Conservation activities in these areas include participatory land-use zoning, patrols reporting new developments to government officials, awareness-raising and incentive-led nest protection schemes

Predictive models can help clarify the distribution of poorly known species but should display strong transferability when applied to independent data. Nevertheless, model transferability for threatened tropical species is poorly studied. We built models predicting the incidence of the critically endangered Bengal Florican (Houbaropsis bengalensis) within the Tonle Sap (TLS) floodplain, Cambodia. Separate models were constructed with soil, land-use, and landscape data and species incidence sampled over the entire floodplain (12,000 km(2)) and from the Kompong Thom (KT) province (4000 km(2)). In each case, the probability of Bengal Florican presence within randomly selected 1 x 1 km squares was modeled by binary logistic regression with multimodel inference. We assessed the transferability of the KT model by comparing predictions with observed incidence elsewhere in the floodplain. In terms of standard model-validation statistics, the KT model showed good spatial transferability. Nevertheless, it overpredicted florican presence outside the KT calibration region, classifying 491 km(2) as suitable habitat compared with 237 km(2) predicted as suitable by the TLS model. This resulted from higher species incidence within the calibration region, probably owing to a program of conservation education and enforcement that has reduced persecution there. Because both research and conservation activity frequently focus on areas with higher density, such effects could be widespread, reducing transferability of predictive distribution models.

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