Dusit Ngoprasert

Human disturbance affects habitat use and behaviour of Asiatic leopard Panthera pardus in Kaeng Krachan National Park, Thailand

Edge effects arising from road construction and other development in protected areas can negatively affect the behaviour of wildlife, particularly large carnivores. The Asiatic leopard Panthera pardus is a large carnivore that may be sensitive to edge effects. Camera trapping was used to assess the influence of human disturbance along forest edges on leopard behaviour and habitat use in a 104 km 2 area of Kaeng Krachan National Park, Thailand. A minimum of four male and two female leopards was recorded in the study area. A Park access road bisecting the study area was not a barrier to leopard movement but movements and activity were affected by human traffic inside the Park. A regression model showed that leopard habitat use increased with distance from human settlements at the forest edge. As in other parts of its range, leopards at Kaeng Krachan National Park tended to show less diurnal activity in areas more heavily used by people compared to areas less used. As is the case with tigers, such responses may pose a threat to leopard population persistence but more research is needed to determine the demographic implications of edge effects for Asiatic leopards and other large tropical carnivores, and the appropriate mitigation strategies required.

Influence of Fruit on Habitat Selection of Asian Bears in a Tropical Forest

ABSTRACT Wild bear populations in Southeast Asia are threatened with extinction, but the ecology and distribution of the 2 species occurring in the regions protected areas is poorly known, so there is little scientific basis underlying conservation strategies. We used bear signs, primarily claw marks on climbed trees, to study habitat selection and distribution of Asiatic black bear (Ursus thibetanus) and sun bear (Helarctos malayanus) across Khao Yai National Park, Thailand from March to December 2008. We found black bear claw marks in 24 of 30 random sample blocks (80%), indicating that this species was widely distributed across Khao Yai. Sun bear signs were much scarcer: their claw marks occurred in 11 blocks (37%); data were too sparse for sun bear so we limited our focus to Asiatic black bear. Using logistic regression, we found that fruit abundance best explained variation in presence of black bear, whereas human disturbance, distance to park edge, elevation, and ground cover had little influence. Fruits appear to be a key resource for Asiatic black bears, and factors affecting fruit abundance or shifts in seasonality (e.g., climate change) will impact bear populations. Knowledge of this relationship will allow managers to be more proactive in managing bears. We recommend using sign surveys for monitoring changes in black bear occupancy as they are inexpensive, efficient, and can be conducted by trained park rangers.

Mapping the distribution of dholes, Cuon alpinus (Canidae, Carnivora), in Thailand

Abstract No recent attempt has been made to survey dhole distribution, or to estimate remaining population numbers. We surveyed 15 protected areas in Thailand with camera traps from 1996 to 2010. We used the photo locations of dholes (n=96) in the maximum entropy (MaxEnt) model along with six environmental variables to model current dhole distribution, as well as species predictive occurrence layers for sambar, red muntjac, wild boar, tiger, and leopard. The MaxEnt model identified the predicted probability of the presence of leopards and sambar as positive and the most important variables in modeling dhole presence, indicating that maintaining a sufficient prey base may be the most important factor determining continued survival of dholes. Roughly 7% of the total land area in Thailand is potentially suitable for dholes. However, surveys to date have focused on protected areas, which make up just a third of the potential suitable areas for dholes. Only in four protected areas do they occur across the entire landscape, suggesting that in the majority of places where they occur, habitats are not uniformly suitable. Using the model, we identified several potential areas where dholes have not been reported, and therefore status surveys are needed, and where future research of the species might be focused.

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

Southeast Asias 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 km(2) ) protected 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 forest (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. However, tapirs may not avoid edges but instead prefer wetter evergreen forest, a habitat type that tended to occur further 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 expected to be less sensitive to disturbance because they are not targets for hunting and trade, and are almost entirely 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 ungulates, and continued legal status for tapirs in the highest category of protection.

Projecting range-wide sun bear population trends using tree cover and camera-trap bycatch data

Monitoring population trends of threatened species requires standardized techniques that can be applied over broad areas and repeated through time. Sun bears Helarctos malayanus are a forest dependent tropical bear found throughout most of Southeast Asia. Previous estimates of global population trends have relied on expert opinion and cannot be systematically replicated. We combined data from 1,463 camera traps within 31 field sites across sun bear range to model the relationship between photo catch rates of sun bears and tree cover. Sun bears were detected in all levels of tree cover above 20%, and the probability of presence was positively associated with the amount of tree cover within a 6-km2 buffer of the camera traps. We used the relationship between catch rates and tree cover across space to infer temporal trends in sun bear abundance in response to tree cover loss at country and global-scales. Our model-based projections based on this “space for time” substitution suggested that sun bear population declines associated with tree cover loss between 2000–2014 in mainland southeast Asia were ~9%, with declines highest in Cambodia and lowest in Myanmar. During the same period, sun bear populations in insular southeast Asia (Malaysia, Indonesia and Brunei) were projected to have declined at a much higher rate (22%). Cast forward over 30-years, from the year 2000, by assuming a constant rate of change in tree cover, we projected population declines in the insular region that surpassed 50%, meeting the IUCN criteria for endangered if sun bears were listed on the population level. Although this approach requires several assumptions, most notably that trends in abundance across space can be used to infer temporal trends, population projections using remotely sensed tree cover data may serve as a useful alternative (or supplement) to expert opinion. The advantages of this approach is that it is objective, data-driven, repeatable, and it requires that all assumptions be clearly stated.

Effect of landscape variables on the long-term decline of Great Argus in the rainforest of Southern Thailand

In Thailand, as for most of South-East Asia, large vertebrates are declining rapidly due to habitat degradation and increasing hunting pressure. Once relatively common in the evergreen forest of Southern Thailand, the Great Argus Argusianus argus is currently limited to a few populations, whose status is currently unknown. In this study we investigated changes in Great Argus abundance over the past 13 years in Hala-Bala Wildlife Sanctuary. Our aim was to estimate and compare the abundance and density of this species from an earlier two-year survey in 2001–2002 and ours in 2014, and to assess the effect of landscape change on its status of the species. We conducted surveys from March to August 2014 during the breeding season. We placed point counts that overlapped the line transects from the 2001–2002 survey. The results indicated a decline of > 35% in mean abundance from 2001 to 2014. In addition, male abundance has shifted and is now positively related to distance from the forest edge. High levels of human disturbance close to the forest edge may have resulted in the birds moving to the core of the forest, suggesting a need to increase protection and management of forest edge areas. In common with other studies of large vertebrates, our results confirm the importance of long-term studies to highlight the negative effects of human disturbance.

Singing Patterns of White-Cheeked Gibbons (Nomascus sp.) in the Annamite Mountains of Laos

Studying the structure and patterns of vocalizations in primates is important to understand their evolution, responses to changing environments, and social behavior, and to design efficient vocalization-based survey techniques. Gibbons (Hylobatidae) are small arboreal apes known for their stereotyped songs. Data on their vocalization patterns remain limited, especially for crested gibbons (Nomascus spp.). We recorded songs of white-cheeked gibbons (Nomascus sp.) heard from listening posts at a site in Nakai–Nam Theun National Protected Area, central-eastern Laos, during a cold dry and a warm dry season, from November 2013 to May 2014, along with weather data. Males typically initiated the duet songs at a mean time of 06:14 h. Duet song bouts lasted a mean of 16 min. Song bout length was relatively constant throughout the study but decreased with the occurrence of wind. On a given day, the first male song started at a mean of 12 min before sunrise and all songs ceased at a mean of 13 min after sunrise. The start time of the first song relative to sunrise did not differ significantly between the two seasons but we found a significant negative relationship between the start time of the first song and both time of sunrise and temperature. The mean number of song bouts heard was significantly larger during the cold dry season than the warm dry season, and we found a significant negative relationship between the number of song bouts heard and temperature. Song rates also increased during days with no rain relative to rainy days. Our findings provide a preliminary understanding of song patterns in Nomascus spp. and can aid the planning and interpretation of surveys that rely on documenting their calls.

Changing Landscapes and Declining Populations of Resident Waterbirds: A 12-Year Study in Bung Boraphet Wetland, Thailand:

Changes in wetland environments can alter the dynamics of waterbird populations. We investigated the effects of hydrological and landscape variables on the abundance of resident waterbirds (ducks, fish-eaters, large waders, small waders, and vegetation gleaners) from 2003 to 2014 in Bung Boraphet, Thailands largest freshwater wetland. Generalized linear mixed models were used to determine the effects of environmental variables on waterbird numbers, and generalized additive mixed models were used to identify the threshold for each effect. The results revealed that the population of all waterbirds declined by 27% from 2003 to 2014 with highest decline of 56% in ducks. Increasing water depth was negatively correlated with the abundance of small waders and vegetation gleaners. Higher concentrations of dissolved oxygen in the water increased the abundance of fish-eaters, while marshy areas were positively associated with the abundance of ducks, large waders, and vegetation gleaners. The abundance of fish-eaters, large waders, and small waders were negatively associated with the spatial area of waterbodies. Expanding human settlements decreased the abundance of vegetation gleaners, while vegetation infested by Mimosa pigra decreased the abundance of large waders. The study concludes that the maintenance of an optimal water depth and quality, preservation of critical marsh habitats, eradication of invasive species, and restrictions on new human settlements adjacent to wetlands are all necessary to conserve resident waterbird populations. Validating these findings in additional research sites is recommended before applying it to a broader landscape level.

Habitat Use of the Saola Pseudoryx nghetinhensis (Mammalia; Bovidae) Based on Local Sightings in the Northern Annamite Mountains of Lao PDR:

The Saola Pseudoryx nghetinhensis (Mammalia; Bovidae) is IUCN Critically Endangered, but its ecology remains almost entirely unknown. Here we present the first characterization of Saola habitat use. We assessed Saola macrohabitat and microhabitat characteristics using Saola sighting location data obtained from local people. The study focused on the Phou Sithon Endangered Species Conservation Area in the northern Annamites of Lao PDR. A geographical information system was used to characterize macrohabitat variables including elevation, abundance of streams, and distance to nearest village associated with each observation. Infinitely weighted logistic regression models were used to assess relationships between detection of Saola and these macro variables. Direct measurements for microhabitat variables for each Saola observation were also collected and compared with other available vegetation data. Twenty-two observations from 18 independent observation points were analyzed. Elevations of the points ranged from 592 to 1,112 m (Median = 747 m) matching previous studies (500–1,400 m). Our regression model indicated abundance of streams affected detection of Saola suggesting it was more likely detected in areas with higher abundances of streams; however, streams were also associated with human travel routes. Our analysis also suggested that Saola were more frequently encountered in primary forest with a high density of trees but were occasionally observed in secondary growth. Most encounters were on animal trails. This information represents an important baseline for future assessments of Saola priority areas, which may assist in searching for possible sites that might harbor this elusive species; however, additional studies of its ecology are urgently needed to guide future management.

Informing decisions on an extremely data poor species facing imminent extinction

Some of the species that are believed to have the highest probability of extinction are also amongst the most poorly known, and this makes it extremely difficult to decide how to spend scarce resources. Assessments of conservation status made on the basis of loss or degradation of habitat and lack of records may provide compelling indications of a decline in geographical range and population size, but they do not help identify where conservation action might be best targeted. Methods for assessing the probability of extinction and for modelling species’ distributions exist, but their data requirements often exceed the information that is available for some of the most urgent conservation cases. Here we use all available information (localities, expert information, climate and landcover) about a high-priority Vietnamese bird species (Edwardss pheasant Lophura edwardsi ) to assess objectively the probability of its persistence, and where surveys or other conservation action should be targeted. It is clear that the species is on the threshold of extinction and there is an urgent need to survey Bach Ma National Park (including the extension) and to consider surveying Ke Go Nature Reserve. This approach has potential to help identify where conservation action should be targeted for other Critically Endangered species for which there is an extreme scarcity of information.