Assessing the biodiversity value of degraded lowland forest in Sumatra, Indonesia

Forest degradation, forest fires, and wildlife poaching have devastated biodiversity in Indonesia. To assess the impact of forest degradation and the potential for recovery, we used birds as a proxy for biodiversity and assessed density estimates (hereafter density) in the degraded lowland forest of Harapan Rainforest Ecosystem Restoration Concession (HRF) in Sumatra. In this study, a total of 149 bird species (from 5,317 individuals) were recorded. Of the 103 species for which densities could be calculated, 45% were lowland bird specialists (i.e. species occurring below 200 m above sea level in Sumatra), including three globally threatened and 41 Near-Threatened species. Comparison with bird densities in degraded forest of Borneo revealed that there was broad similarity across taxa but three species had significantly higher density, and four had significantly lower density, in HRF. The mosaic of degraded forest habitats in different stages of regeneration in HRF appears to support more individuals of some species, especially woodpeckers, than the Bornean sites, but fewer individuals of other species. Determining bird densities is essential to establish population baselines, allowing comparisons between sites and over time. The present study fills one gap, but we urge others to conduct similar studies to provide a better understanding of the temporal and spatial variation in bird density in Southeast Asia’s degraded forests

Nesting cycle and nest tree characteristics of the Helmeted Hornbill Rhinoplax vigil, compared to the Wreathed Hornbill Rhyticeros undulatus, in Sumatran lowland rainforest

Hornbills provide a seed dispersal service for rainforest trees, but the persistence of hornbill populations depends on the availability of old trees that provide cavities for their nests. The Helmeted Hornbill Rhinoplax vigil is Critically Endangered, due to both forest destruction and an inhumane illegal trade in their bill casques, yet little is known about its nests and breeding biology. Here we describe the nest tree and external nest characteristics of a pair of Helmeted Hornbills in Bukit Barisan Selatan National Park, Lampung, Sumatra, and compare them with observations of two nests of the Wreathed Hornbill Rhyticeros undulatus less than 1 km away. As in a previous study, the Helmeted Hornbill (HH) nest was in a large dipterocarp, and possessed a stump next to the entrance that the male used as a perch when feeding the female or chick. The nest entrance dimensions and bole diameter of the nest tree were much larger than those of the two Wreathed Hornbill (W1 and W2) nests. Egg laying in HH took place in February, while in W1 and W2, eggs were laid much later, between late May and July. The maximum nesting cycle of the Helmeted Hornbill was an astonishing 137 days (4.5 months), close to the minimum period (range, 138-151) for a nest of the species in Peninsular Malaysia. This may be longer than the nesting cycle of the Wreathed Hornbill, but additional data are needed

Planning for megafauna recovery in the tropical rainforests of Sumatra

Human-induced forest loss has had devastating impacts on biodiversity. Mammal populations in the tropics have been hit particularly hard by the resulting habitat loss, fragmentation and degradation, as well as by overhunting which often goes hand-in-hand. While declines in these populations are generally well documented, few studies offer a pathway for their recovery. Here, we test the association between changes in forest habitat and occupancy trends of Sumatran megafauna (elephant and tiger) and key tiger prey species (wild boar and sambar) in the Leuser Ecosystem: a large forest landscape on the Indonesian island of Sumatra. For elephant and tiger, we develop additional occupancy models to predict their respective spatial distribution under different scenarios of forest loss and gain (through restoration and increased connectivity) to provide a blueprint for avoiding future species loss and assisting with their population recovery. From 2000 to 2019, 254,722 ha (6.7%) of natural forest was converted, primarily to plantations and shrubs. The species-specific responses over the study period revealed that the occurrence of elephant declined along the west, with a range shift to the northeast of Leuser, whereas wild boar underwent a dramatic widespread decline and although sambar experienced losses around the forest edge, it remained widespread in the interior forest, while tiger occupancy remained stable. Modelling habitat loss and fragmentation led to an unsurprising demise of Sumatran megafauna, whereas strategic investments that reconnected several forest patches provided disproportionately large benefits for their recovery through the recolonization of former parts of their range. Indonesia has achieved six consecutive years of declining forest loss rates, and our study’s findings can build off this conservation success by supporting improved provincial spatial planning and field-based restoration efforts that avoid declines of threatened megafauna species and act as a catalyst for rewilding a landscape of global importance

Assessing the potential for avifauna recovery in degraded forests in Indonesia

Marthy, William, Clough, Yann, Tscharntke, Teja (2017): Assessing the potential for avifauna recovery in degraded forests in Indonesia. Raffles Bulletin of Zoology 65: 35-48, DOI: http://doi.org/10.5281/zenodo.535584

Globally threatened Sunda Blue Flycatcher Cyornis caerulatus: synthesis of global records and recent records from Sumatra

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Towards coexistence: can people's attitudes explain their willingness to live with Sumatran elephants in Indonesia?

Understanding coexistence between humans and threatened wildlife is a central focus in conservation. Way Kambas National Park in Sumatra Island, Indonesia, harbors one of the largest populations of the critically endangered Sumatran elephant (Elephas maximus sumatranus). The people who live alongside this population are affected by intensive crop foraging. Our study investigated the factors which influenced attitudes toward elephants. We then evaluated the implications of reported attitudes for future willingness to live with elephants. We surveyed 660 respondents in 22 villages around the park. People generally reported positive attitudes toward elephants (smartness 95%, usefulness 62%, importance 57%, and pleasantness 53%), apart from where human safety was concerned (safety 11%). Each dimension of attitude was explained by different factors including age, gender, knowledge of elephants, and distance to crop foraging locations. Most respondents (62%) expressed no willingness to coexist with elephants. Such willingness was lower when elephants were perceived to be more dangerous, but higher if beliefs in the benefits of elephants were greater. Efforts to improve crop foraging mitigation practice and to increase people's awareness of elephant benefits may promote support for their conservation. Through this study, we advocate the integration of social science to promote human–wildlife coexistence strategies, an approach that is currently limited in Indonesia.Published versionThis study was funded by US Fish and Wildlife Service

Measuring the impact of the pet trade on Indonesian birds

The trade in wild animals involves one-third of the world's bird species and thousands of other vertebrate species. Although a few species are imperiled as a result of the wildlife trade, the lack of field studies makes it difficult to gauge how serious a threat it is to biodiversity. We used data on changes in bird abundances across space and time and information from trapper interviews to evaluate the effects of trapping wild birds for the pet trade in Sumatra, Indonesia. To analyze changes in bird abundance over time, we used data gathered over 14 years of repeated bird surveys in a 900-ha forest in southern Sumatra. In northern Sumatra, we surveyed birds along a gradient of trapping accessibility, from the edge of roads to 5 km into the forest interior. We interviewed 49 bird trappers in northern Sumatra to learn which species they targeted and how far they went into the forest to trap. We used prices from Sumatran bird markets as a proxy for demand and, therefore, trapping pressure. Market price was a significant predictor of species declines over time in southern Sumatra (e.g., given a market price increase of approximately $50, the log change in abundance per year decreased by 0.06 on average). This result indicates a link between the market-based pet trade and community-wide species declines. In northern Sumatra, price and change in abundance were not related to remoteness (distance from the nearest road). However, based on our field surveys, high-value species were rare or absent across this region. The median maximum distance trappers went into the forest each day was 5.0 km. This suggests that trapping has depleted bird populations across our remoteness gradient. We found that less than half of Sumatra's remaining forests are >5 km from a major road. Our results suggest that trapping for the pet trade threatens birds in Sumatra. Given the popularity of pet birds across Southeast Asia, additional studies are urgently needed to determine the extent and magnitude of the threat posed by the pet trad