Impacts of hunting on tropical forests in Southeast Asia.

Although deforestation and forest degradation have long been considered the most significant threats to tropical biodiversity, across Southeast Asia (Northeast India, Indochina, Sundaland, Philippines) substantial areas of natural habitat have few wild animals (>1 kg), bar a few hunting-tolerant species. To document hunting impacts on vertebrate populations regionally, we conducted an extensive literature review, including papers in local journals and reports of governmental and nongovernmental agencies. Evidence from multiple sites indicated animal populations declined precipitously across the region since approximately 1980, and many species are now extirpated from substantial portions of their former ranges. Hunting is by far the greatest immediate threat to the survival of most of the region's endangered vertebrates. Causes of recent overhunting include improved access to forests and markets, improved hunting technology, and escalating demand for wild meat, wildlife-derived medicinal products, and wild animals as pets. Although hunters often take common species, such as pigs or rats, for their own consumption, they take rarer species opportunistically and sell surplus meat and commercially valuable products. There is also widespread targeted hunting of high-value species. Consequently, as currently practiced, hunting cannot be considered sustainable anywhere in the region, and in most places enforcement of protected-area and protected-species legislation is weak. The international community's focus on cross-border trade fails to address overexploitation of wildlife because hunting and the sale of wild meat is largely a local issue and most of the harvest is consumed in villages, rural towns, and nearby cities. In addition to improved enforcement, efforts to engage hunters and manage wildlife populations through sustainable hunting practices are urgently needed. Unless there is a step change in efforts to reduce wildlife exploitation to sustainable levels, the region will likely lose most of its iconic species, and many others besides, within the next few years.

Using occupancy-based surveys and multi-model inference to estimate abundance and distribution of crested gibbons (Nomascus spp.) in central Laos.

Reliable assessments of species' status are prerequisites for monitoring the success of conservation programmes. However, survey conditions such as terrain and inaccessibility, compounded by the low densities of many species across Southeast Asia and other parts of the world are considerable barriers to obtaining robust populations estimates. We used an occupancy-based approach and multi-model inference to generate occupancy and abundance estimates for northern white-cheeked crested gibbons Nomascus leucogenys and southern white-cheeked crested gibbons N. siki in the Nam Kading National Protected Area (NKNPA) in central Lao Peoples' Democratic Republic (hereafter Laos). We present these estimates for gibbons within the context of a strategy designed to monitor multiple species and discuss the practical challenges to obtaining sufficient data for robust population estimates to detect change in gibbon status over time. We surveyed approximately 210 km2 of habitat and estimate an abundance of 45 (SE = 17, CV = 37%) groups, giving an average site abundance of 0.21 (SE = 0.08, CV = 37%) groups per km2 . We make recommendations for ongoing gibbon monitoring and discuss the wider implications for cost effective wildlife monitoring in Laos. Am. J. Primatol. 78:462-472, 2016. © 2015 Wiley Periodicals, Inc.

Experimental estimation of snare detectability for robust threat monitoring.

Hunting with wire snares is rife within many tropical forest systems, and constitutes one of the severest threats to a wide range of vertebrate taxa. As for all threats, reliable monitoring of snaring levels is critical for assessing the relative effectiveness of management interventions. However, snares pose a particular challenge in terms of tracking spatial or temporal trends in their prevalence because they are extremely difficult to detect, and are typically spread across large, inaccessible areas. As with cryptic animal targets, any approach used to monitor snaring levels must address the issue of imperfect detection, but no standard method exists to do so. We carried out a field experiment in Keo Seima Wildlife Reserve in eastern Cambodia with the following objectives: (1) To estimate the detection probably of wire snares within a tropical forest context, and to investigate how detectability might be affected by habitat type, snare type, or observer. (2) To trial two sets of sampling protocols feasible to implement in a range of challenging field conditions. (3) To conduct a preliminary assessment of two potential analytical approaches to dealing with the resulting snare encounter data. We found that although different observers had no discernible effect on detection probability, detectability did vary between habitat type and snare type. We contend that simple repeated counts carried out at multiple sites and analyzed using binomial mixture models could represent a practical yet robust solution to the problem of monitoring snaring levels both inside and outside of protected areas. This experiment represents an important first step in developing improved methods of threat monitoring, and such methods are greatly needed in southeast Asia, as well as in as many other regions.

Protecting tropical forests from the rapid expansion of rubber using carbon payments.

Expansion of Hevea brasiliensis rubber plantations is a resurgent driver of deforestation, carbon emissions, and biodiversity loss in Southeast Asia. Southeast Asian rubber extent is massive, equivalent to 67% of oil palm, with rapid further expansion predicted. Results-based carbon finance could dis-incentivise forest conversion to rubber, but efficacy will be limited unless payments match, or at least approach, the costs of avoided deforestation. These include opportunity costs (timber and rubber profits), plus carbon finance scheme setup (transaction) and implementation costs. Using comprehensive Cambodian forest data, exploring scenarios of selective logging and conversion, and assuming land-use choice is based on net present value, we find that carbon prices of $30-$51 per tCO2 are needed to break even against costs, higher than those currently paid on carbon markets or through carbon funds. To defend forests from rubber, either carbon prices must be increased, or other strategies are needed, such as corporate zero-deforestation pledges, and governmental regulation and enforcement of forest protection.

Identifying conservation successes, failures and future opportunities; assessing recovery potential of wild ungulates and tigers in Eastern Cambodia.

Conservation investment, particularly for charismatic and wide-ranging large mammal species, needs to be evidence-based. Despite the prevalence of this theme within the literature, examples of robust data being generated to guide conservation policy and funding decisions are rare. We present the first published case-study of tiger conservation in Indochina, from a site where an evidence-based approach has been implemented for this iconic predator and its prey. Despite the persistence of extensive areas of habitat, Indochina's tiger and ungulate prey populations are widely supposed to have precipitously declined in recent decades. The Seima Protection Forest (SPF), and broader Eastern Plains Landscape, was identified in 2000 as representing Cambodia's best hope for tiger recovery; reflected in its designation as a Global Priority Tiger Conservation Landscape. Since 2005 distance sampling, camera-trapping and detection-dog surveys have been employed to assess the recovery potential of ungulate and tiger populations in SPF. Our results show that while conservation efforts have ensured that small but regionally significant populations of larger ungulates persist, and density trends in smaller ungulates are stable, overall ungulate populations remain well below theoretical carrying capacity. Extensive field surveys failed to yield any evidence of tiger, and we contend that there is no longer a resident population within the SPF. This local extirpation is believed to be primarily attributable to two decades of intensive hunting; but importantly, prey densities are also currently below the level necessary to support a viable tiger population. Based on these results and similar findings from neighbouring sites, Eastern Cambodia does not currently constitute a Tiger Source Site nor meet the criteria of a Global Priority Tiger Landscape. However, SPF retains global importance for many other elements of biodiversity. It retains high regional importance for ungulate populations and potentially in the future for Indochinese tigers, given adequate prey and protection.