Road induced edge effects on a forest bird community in tropical Asia

Background: Edge effects cause changes in bird community richness, abundance, and/or distribution within a landscape, but the avian guilds most influenced can vary among regions. Although Southeast Asia has the highest rates of deforestation and projected species loss, and is currently undergoing an explosive growth in road infrastructure, there have been few studies of the effects of forest edges on avian communities in this region.Methods: We examined avian community structure in a dry evergreen forest in northeastern Thailand adjacent to a five-lane highway. We evaluated the richness and abundance of birds in 11 guilds at 24 survey points on three parallel transects perpendicular to the edge. At each point, 10-min surveys were conducted during February-August 2014 and March-August 2015. Vegetation measurements were conducted at 16 of the bird survey points and ambient noise was measured at all 24 survey points.Results: We found a strongly negative response to the forest edge for bark-gleaning, sallying, terrestrial, and understory insectivores and a weakly negative response for arboreal frugivore-insectivores, foliage gleaning insectivores, and raptors. Densities of trees and the percentage canopy cover were higher in the interior, and the ambient noise was lower. In contrast, arboreal nectarivore-insectivores responded positively to the forest edge, where there was a higher vegetation cover in the ground layer, a lower tree density, and a higher level of ambient noise.Conclusion: Planners should avoid road development in forests of high conservation value to reduce impacts on biodiversity. Where avoidance is impossible, a number of potential mitigation methods are available, but more detailed assessments of these are needed before they are applied in this region.

Securing a future for wild Indochinese tigers:Transforming tiger vacuums into tiger source sites

A century ago,tigers(Panthera tigris Linnaeus,1758)were so common in parts of Southeast Asia as to be considered pests,and governments sponsored their killing.Habitat loss and fragmentation,market-driven poaching and loss of prey have since led to the disappearance of Indochinese tigers from most their former range.Despite 15 years of dedicated tiger conservation funding,national estimates of Indochinese tiger subpopulations can at best only be roughly approximated.The future for the subspecies appears grim unless very focused efforts can be applied to stabilize and recover subpopulations.On a regional scale,the 2 proposed subspecies Panthera tigris corbetti and P.tigris jacksoni are effectively managed as separate conservation units.Evaluating where to place conservation efforts should consider the vulnerability(likelihood of extinction)and irreplaceability(likelihood that an area contributes uniquely to regional conservation)of tiger subpopulations.Only 1 site in Thailand supporting<200 individuals(Huai Kha Khaeng-Thung Yai)is considered low vulnerability,and is irreplaceable.Five sites in Lao,Thailand and Peninsular Malaysia are medium vulnerability and irreplaceable.Priorities at these 6 sites are to double tiger numbers within 10 years through protection and monitoring.Seven sites in Lao,Thailand and Myanmar are high vulnerability and irreplaceable,and might be recovered if government commitment to tigers,staff capacity and legal frameworks for tiger protection are established.Tigers are extremely vulnerable or even extinct in Cambodia’s Eastern Plains and the site is irreplaceable for tigers because it represents the only large(>10000 km^(2))block of dry forest habitat available in the region.A reintroduction program is the only option to recover tigers there.

Comparative sensitivity to environmental variation and human disturbance of Asian tapirs (Tapirus indicus) and other wild ungulates in Thailand

Southeast Asia’s tropical forests suffer the highest rates of deforestation and disturbance of any on Earth,with poorly understood impacts on native fauna.Asian tapirs(Tapirus indicus)are among the least studied of the large mammals in these forests.Using records from 9 camera trap surveys in 7 of the largest(>1000 km2)pro-tected area complexes,we assessed the influence of environmental variation and human-induced disturbance on tapir occurrence.Tapirs were detected at 13%of locations sampled,significantly associated with evergreen for-est(P<0.001).A multiple logistic regression model predicted tapir presence 87%of the time.According to this model,tapir occurrence was positively influenced by annual rainfall and proximity to the forest edge.Howev-er,tapirs may not avoid edges but instead prefer wetter evergreen forest,a habitat type that tended to occur fur-ther from the forest edge at higher elevations in our particular study sites(P<0.001).By comparison,4 other wild ungulate species that share habitats with tapirs showed a range of differing responses.Tapirs are expect-ed to be less sensitive to disturbance because they are not targets for hunting and trade,and are almost entire-ly active at night,so avoid peak traffic periods in parks.Tapir populations in Thailand may be more stable than in other parts of their global range because rates of forest loss have decreased>40%over the past 20 years.We recommend surveys to fill gaps in the understanding of the status in lesser-known protected areas,research to better understand the fine-scale environmental influences on behavior and habitats of tapirs,and other forest un-gulates,and continued legal status for tapirs in the highest category of protection.