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.

Roost selection of the endangered Spotted Greenshank(Tringa guttifer) in critical habitat in the Inner Gulf of Thailand

Background: Roost-site quality can significantly affect the individual fitness of shorebirds, but roost sites remain poorly described for many threatened species on the East Asian–Australasian Flyway. We studied roost-site selection of the globally endangered Spotted Greenshank (Tringa guttifer) in the Inner Gulf of Thailand, an area which supports approximately 24% of their global wintering population, during two non-breeding seasons (October 2014–May 2015 and December 2015–February 2016). Methods: We measured nine variables associated with roost site characteristics including water depth, indicators of disturbance/predation risk, and associations with other shorebird species. We predicted that roost ponds with shallow water in proximity to foraging sites would receive higher usage than those further away. Results: A total of 94 sites were measured of which 46 were used for roosts with 23 used repeatedly. All used sites were human-modified ponds, of which 44 were used for salt farming and two used for aquaculture. Roosts were on average 1.10 ± 0.78 (SE) km from foraging sites and 5.8 ± 2.4 cm deep. The most supported model indicated that roost sites were negatively associated with distance to foraging sites and positively associated with the presence of Grey Plover (Pluvialis squatarola) and water depth. Conclusions: Traditional saltpans and other artificial wetlands near (< 1 km) mudflats serve as the primary high-tide roost habitat in the Inner Gulf of Thailand for this Spotted Greenshank population and perhaps seven other globally threatened or near-threatened species. Critically, all observed roost sites are on private land with no formal protection and thus will require creative public–private partnerships to manage sustainably.

Plant-frugivore interactions in an intact tropical forest in north-east Thailand

Fleshy-fruited plants in tropical forests largely rely on vertebrate frugivores to disperse their seeds.Although this plant-animal interaction is typically considered a diffuse mutualism,it is fundamental as it provides the template on which tropical forest communities are structured.We applied a mutualistic network approach to investigate the relationship between small-fruited fleshy plant species and the fruit-eating bird community in an intact evergreen forest in north-east Thailand.A minimum of 53 bird species consumed fruits of 136 plant species.Plant-avian frugivore networks were highly asymmetrical,with observed networks filling 30%of all potential links.Whereas some of the missing links in the present study might be due to undersampling,forbidden links can be attributed to size constraints,accessibility and phenological uncoupling,and although the majority of missing links were unknown(58.2%),many were probably due to a given bird species being either rare or only a very occasional fruit eater.The most common frugivores were bulbuls,barbets and fairy-bluebirds,which were responsible for the majority of fruit removal from small fleshy fruited species in our system.Migratory birds seemed to be a minor component of the plant-frugivore networks,accounting for only 3%of feeding visits to fruiting trees;they filled 2%of the overall potential networks.The majority of interactions were generalized unspecific;however,Saurauia roxburghii Wall.appeared to be dependent on flowerpeckers for dispersal,while Thick-billed Pigeons were only seen to eat figs.