Blog written by Susana Rostro-García. Read the full paper here. Featured image shows a jungle cat in threatened dry deciduous forests of eastern Cambodia © Rostro-García et. al. / WWF-Cambodia / WildCRU
Southeast Asia, a beautiful region well known for being one of the most important biodiversity hotspots worldwide, is amidst a conservation crisis. Despite supporting more threatened species than any other continental area, the wildlife in Southeast Asia has been considerably understudied, which alongside the rapid drivers of species loss, make protecting biodiversity highly challenging. The open dry deciduous forests (DDF) of Southeast Asia, which currently cover about 15-20% of the region, support several globally irreplaceable species, many of which are classified as threatened. However, the DDF are now the most threatened of all forest types of the region, and despite their relevance there has been little research on wildlife species in this habitat.
One of the major differences between the evergreen forests, which dominate the region, and DDF, is that the latter are characterized by an open canopy and abundant grassland. Also, in DDF annual dry season fires occur, resulting in most water sources drying up and large decreases in small vertebrate prey. Four species of cats are known to occupy DDF habitat, but only one of these species appears to be a DDF specialist in Southeast Asia: the jungle cat Felis chaus. This tawny medium-sized cat is relatively common in India and southwestern Asia, but it appears to have suffered drastic declines in Southeast Asia because of the habitat modification within DDF landscapes, and the pervasive indiscriminate snaring in the region. It is thought that the jungle cat now occurs only in small and isolated populations, making it one of the rarest felids in mainland Southeast Asia – yet almost nothing is known about the ecology of this species.
We investigated the ecology of jungle cats in a landscape in eastern Cambodia which contains one of the largest tracts of threatened DDF remaining in the region. Specifically, we worked in a site known as the Serengeti of Asia – the Eastern Plains Landscape of Cambodia. This landscape is dominated by DDF and has been identified as the last major stronghold for jungle cats in Southeast Asia. We used camera-trap surveys and DNA-confirmed scats to study this species and the strategies it uses to coexist with a common, similar-sized felid that occurred in our study site, the leopard cat Prionailurus bengalensis.
We found that the diet of jungle cats was relatively diverse and consisted of mostly of small rodents, followed by squirrels, hares, birds, and reptiles. In contrast, leopard cats had a less diverse diet dominated by smaller prey, primarily small rodents. Despite these differences, the diets of these species had high overlap because both cats were consuming predominantly small rodents. We also found that both species were primarily nocturnal and thus had high temporal overlap, which was unexpected because previous studies reported that jungle cats were more diurnal than other felids. This nocturnal activity was unlikely to be due to jungle cats avoiding larger carnivores (e.g., leopards Panthera pardus, dholes Cuon alpinus) because these larger species also were nocturnal in our study area. We believe jungle cats may have favored nocturnal activity because the camera trapping surveys were carried out during the dry season, when monthly temperatures are the highest and the grassy understory burns. Alternatively, jungle cats may have become nocturnal to avoid humans because illegal human activity occurred primarily during the daytime.
The investigation in habitat use of these species revealed that jungle cats used DDF almost exclusively but had low occupancy. This was remarkable given that evergreen forests in the area did not burn and contained a higher number of small rodents compared to nearby DDF. The fact that jungle cats used DDF almost exclusively suggested that prey abundance alone did not affect the habitat use of jungle cats, and that the specialization of this species for hunting in open habitats may preclude it from regularly using closed evergreen forests. In contrast, the data from both scats and camera traps indicated that leopard cats were more abundant habitat generalists that used both DDF and evergreen forests, providing confirmation that leopard cats are a behaviorally flexible habitat generalist. The use of evergreen habitat by leopard cats was likely responsible for the abundance of this species on our study site, given the larger number of rodents and lack of fires in this habitat compared to DDF. The broader habitat use of leopard cats, together with the lower occupancy and more diverse diet of jungle cats, likely facilitated the coexistence of these species.
Our study confirmed that jungle cats are DDF specialists that likely persist in low numbers due to the harsh conditions of the dry season in this habitat, which includes annual fires and substantial decreases in small prey. Of the three recognized subspecies of jungle cats, the one that occurs in Southeast Asia Felis chaus fulvidina is the only one that is a conservation concern because it has become one the rarest felids in the region. Although jungle cats might be able to occur in open scrub and other secondary habitats in Southeast Asia, because of the anthropogenic pressures these habitats are now unusable by them, leaving DDF as the only major remaining suitable habitat for jungle cats. Our study suggests this species might be rare not only because of poaching and limited availability of DDF, but also likely because of the seemingly low carrying capacity of jungle cats in this habitat owing to its harsh dry-season conditions. Consequently, our results indicate that relatively large areas of DDF will be required for the long-term conservation of this rare felid in Southeast Asia. Unfortunately, DDF is easily accessible to humans, who are increasingly causing habitat destruction and overhunting species within it. Immediate conservation action should be taken to conserve jungle cats in Southeast Asia by making and implementing conservation plans that include the protection of large tracts of DDF and increased law enforcement activities for these areas. Only with implementation of better conservation strategies for DDF will the long-term conservation of jungle cats and other DDF specialists be feasible in Southeast Asia.