Thomas N. E. Gray

Generality of Models that Predict the Distribution of Species: Conservation Activity and Reduction of Model Transferability for a Threatened Bustard

Predictive models can help clarify the distribution of poorly known species but should display strong transferability when applied to independent data. Nevertheless, model transferability for threatened tropical species is poorly studied. We built models predicting the incidence of the critically endangered Bengal Florican (Houbaropsis bengalensis) within the Tonle Sap (TLS) floodplain, Cambodia. Separate models were constructed with soil, land-use, and landscape data and species incidence sampled over the entire floodplain (12,000 km(2)) and from the Kompong Thom (KT) province (4000 km(2)). In each case, the probability of Bengal Florican presence within randomly selected 1 x 1 km squares was modeled by binary logistic regression with multimodel inference. We assessed the transferability of the KT model by comparing predictions with observed incidence elsewhere in the floodplain. In terms of standard model-validation statistics, the KT model showed good spatial transferability. Nevertheless, it overpredicted florican presence outside the KT calibration region, classifying 491 km(2) as suitable habitat compared with 237 km(2) predicted as suitable by the TLS model. This resulted from higher species incidence within the calibration region, probably owing to a program of conservation education and enforcement that has reduced persecution there. Because both research and conservation activity frequently focus on areas with higher density, such effects could be widespread, reducing transferability of predictive distribution models.

Distribution, status and conservation of the Bengal Florican Houbaropsis bengalensis in Cambodia

Summary The Bengal Florican is a ‘Critically Endangered’ bustard (Otididae) restricted to India, Nepal and southern Indochina. Fewer than 500 birds are estimated to remain in the Indian subcontinent, whilst the Indochinese breeding population is primarily restricted to grasslands surrounding the Tonle Sap lake, Cambodia. We conducted the first comprehensive breeding season survey of Bengal Florican within the Tonle Sap region (19,500 km 2 ). During 2005/06 and 2006/07 we systematically sampled 1-km squares for territorial males. Bengal Florican were detected within 90 1-km squares at a mean density of 0.34 males km � 2 which, accounting for unequal survey effort across grassland blocks, provides a mean estimate of 0.2 males km � 2 . Based on 2005 habitat extent, the estimated Tonle Sap population is 416 adult males (333–502 6 95% CI), more than half of them in Kompong Thom province. Tonle Sap grasslands are rapidly being lost due to intensification of rice cultivation and, based on satellite images, we document declines of 28% grassland cover within 10 grassland blocks between January 2005 and March 2007. Based on mean 2005 population densities the remaining grassland may support as few as 294 adult male florican, a decline of 30% since 2005. In response to these habitat declines almost 350 km 2 of grassland have been designated as protected areas, set aside for biodiversity and local livelihoods. Conservation activities in these areas include participatory land-use zoning, patrols reporting new developments to government officials, awareness-raising and incentive-led nest protection schemes.

Establishing a monitoring baseline for threatened large ungulates in eastern Cambodia

Monitoring ungulate populations is an essential part of wildlife management with ungulates performing essential ecosystem roles including structuring populations of large carnivores. A number of ungulate species in Southeast Asia are also globally threatened and are therefore important conservation targets in their own right. We estimated large (> 15 kg) ungulate densities in two protected areas, i.e. Mondulkiri Protected Forest and Phnom Prich Wildlife Sanctuary, in eastern Cambodia using distance-based line transect sampling. During the 2009/2010 and 2010/2011 dry seasons, we surveyed 110 line transects (randomly distributed across 3,406 km2) for a total of 1,310 km. We used DISTANCE 6.0 to model detection functions from observations of banteng Bos javanicus, wild pig Sus scrofa and red muntjac Muntiacus muntjak generating estimates of group density, cluster size and individual density. Estimated densities ± SE were 1.1 ± 0.2 individual banteng/km2, 1.4 ± 0.4 individual wild pig/km2 and 2.2 ± 0.2 individual red muntjac/km2 giving an overall density of approximately 4.7 large ungulates/km2. Although wild pig and red muntjac densities were within the range of estimates reported from ecologically similar protected areas in tropical Asia, overall large ungulate density is much lower than the intrinsic carrying capacity of deciduous dipterocarp forest. This appears largely to be due to the scarcity of large deer (i.e. hog deer Axis porcinus, sambur Cervus unicolor and Elds deer Cervus eldii) as a result of extensive historic hunting. Current large ungulate densities appear too low to support a viable tiger Panthera tigris population in the long term, and ungulate recovery, driven by strong protected area management, needs to be achieved before tiger populations can be restored.

First structured camera-trap surveys in Karen State, Myanmar, reveal high diversity of globally threatened mammals

The hill forests of Karen State, Myanmar, were previously inaccessible to biologists and conservationists for security and political reasons. We have, however, now been able to conduct six surveys across the area, using camera traps, for a total of 9,511 trap-nights, to ascertain the presence of threatened mammal species. We obtained 4,191 records of at least 31 mammal species, including 17 categorized as Near Threatened, Vulnerable or Endangered on the IUCN Red List. Carnivores were especially diverse, with 19 species recorded, indicating a globally significant community, including the tiger Panthera tigris , leopard Panthera pardus and dhole Cuon alpinus . Our methodology was not appropriate for estimating relative abundance or occupancy but the species richness of the mammal community, the number of records and the number of locations where species were detected suggest the area is important for the conservation of a globally threatened mammal community that is in decline across the majority of its range. Despite long-standing conservation efforts undertaken by the Karen people, their forests are threatened by hunting and habitat loss. These threats are likely to be exacerbated as political change brings rapid development. Urgent action is thus needed to assist the Karen people to protect one of South-east Asias last intact rich and diverse ecosystems.

Density and Activity Patterns of the Globally Significant Large Herbivore Populations of Cambodia’s Eastern Plains Landscape

The northern and eastern plains of Cambodia support the largest extent of lowland deciduous forest remaining in Southeast Asia. This landscape has also been identified as the highest priority site for tiger Panthera tigris recovery in Indochina. We estimated ungulate tiger prey densities using distance-based line transect sampling from two protected areas in the Eastern Plains Landscape between 2009 and 2011. Densities for large ungulates ranged from 1.1 ± SE 0.2 individuals/km2 for banteng Bos javanicus to 2.2 ± SE 0.2 individuals km2 for red muntjac Muntiacus muntjak. The ungulate activity patterns were correlated with activity patterns of extant large carnivores in the landscape with leopard Panthera pardus and dhole Cuon alpinus showing substantial activity pattern overlap with wild pig Sus scrofa and red muntjac, respectively. Overall tiger prey biomass was more than 540 kg/km2 of which the endangered banteng comprised greater than 80 %. However, ungulate densities were much lower than in ecologically similar sites in South Asia. This was mainly due to the absence of large deer species like Cervus deer, which have historically been extensively hunted. Nevertheless, the Eastern Plains landscape likely supports 50–60 % of the global banteng population and remains a high priority area for the conservation of large herbivores in Southeast Asia.

Rhinoceros horns in trade on the Myanmar–China border

The illegal trade in rhinoceros horn, driven largely by the demand from East and South-east Asia, is a major impediment to the conservation of rhinoceroses globally. We surveyed the town of Mong La, in eastern Myanmar on the border with China, for the presence of rhinoceros horn. No rhinoceros horn was observed in 2006 or 2009, and other African wildlife was rare or absent. During visits in 2014 and 2015 we observed two horns, presumed to be of the white rhinoceros Ceratotherium simum , and one horn tip, small discs from the horn core, horn powder and horn bangles. Shops selling rhinoceros horn all specialized in high-end and high-value wildlife, mostly for decorative purposes, including whole elephant tusks, carved elephant ivory, carved hippopotamus Hippopotamus amphibius canines, and tiger Panthera tigris skins. Organized criminal syndicates are involved in the wildlife trade between Myanmar and Africa, possibly via China. Mong Las geographical position on the border with China, limited control by the central Myanmar Government, and the presence of the Chinese entertainment industry provide ideal conditions for a global wildlife trade hub catering for the Chinese market. Solutions require more intense collaboration between the Myanmar and Chinese authorities to curb the trade in African rhinoceros horn in this part of Asia.