There were 14,000 Pileated gibbons (Hylobates pileatus) in southeast Thailand in 2005, the last time a census survey was done. No one knows what those numbers look like today. The animals are falling victim to illegal hunting, which is the most serious threat to wildlife across Southeast Asia according to a recent study.
The gibbons are especially being poached as bushmeat in Thap Lan National Park by poachers who feed on them when they venture deep into the forest to cut Endangered rosewood trees. ‘Hongmu’ (red wood) timber imports from the Mekong region to China between 2000 and 2014 were valued at nearly US $2.4 billion.
Underfunded and under-equipped Thai park rangers regularly engage in firefights with the armed loggers, but it is believed that gibbon numbers continue to fall, as the animals are easily spotted when they sing, and are shot out of the trees.
“In the past we used to hear [the gibbons singing] a lot, but now we don’t hear them so much. I think it’s people going into the forest to log that is affecting them,” said Surat Monyupanao, head ranger at Thap Lan National Park.
Thailand’s Pileated gibbons (Hylobates pileatus) face a new, still largely undocumented threat: illegal loggers are penetrating deep into the forests of the nation’s national parks to cut down Endangered Siamese rosewood trees (Dalbergia Cochinchinensis). While there, the poachers are feeding on the primates and other wildlife. Wildlife rangers in the country’s Thap Lan National Park have taken photos of the carnage, showing the loggers grisly harvest of gibbons and other animals for bushmeat.
Covering 2,200 square kilometers (849 square miles), Thap Lan is one of four national parks, and a wildlife sanctuary, that make up Thailand’s Dong Phayayen-Khao Yai Forest Complex (DPKY-FC). Designated a UNESCO World Heritage site in 2005, DPKY is one of Southeast Asia’s last remaining tracts of globally significant lowland dipterocarp tropical forest ecosystem. It is an important wildlife stronghold for over 800 species, including globally threatened and endangered animals such as the Asian elephant, Asiatic black bear, Malayan sun bear, banteng (a species of wild cattle), hornbills, slow loris, Siamese crocodile and Sunda pangolin.
Pileated gibbons are classified as Endangered on the IUCN’s Red List, with their numbers rapidly decreasing across Thailand, Cambodia and Laos PDR — the species’ three range states. Populations are believed to have declined by over 50 percent in just 3 generations (about 45 years) between 1970 and 2015.
Hunted toward extinction
A medium-sized primate weighing around 5-6 kilograms (11-13 pounds), Pileated gibbons live in mated pairs together with their offspring. Almost completely arboreal, the species is predominantly frugivorous, spending more than 60 percent of its feeding time on fruit.
As with other species of gibbons, Pileated gibbons sing incredible duets in the forest canopy, with their ethereal songs audible from more than 1.5 kilometers (0.9 miles) away. The females launch into “great calls”, while the males sing in overlapping responses. Naturalist and explorer Alexander Henri Mouhot (1826-1861) described “jungles full of monkeys uttering their plaintive cries” during his expedition to Southeast Asia while collecting animal specimens for London’s Natural History Museum.
Today, those songs are being replaced by silence as the forests empty of wildlife. Thailand is home to three other gibbon species beside the Pileated gibbon — including the white-handed or lar gibbon (Hylobates lar), agile gibbon (Hylobates agilis), and siamang (Symphalangus syndactylus) — all are now listed as Endangered by the IUCN.
Southeast Asian gibbons are among 301 mammal species worldwide threatened with extinction due to hunting for bushmeat, and by large-scale commercial hunting, according to the first ever worldwide assessment of the impact of hunting on terrestrial mammals, published in October 2016 in the Royal Society Open Science journal. A study published in September 2016 in Conservation Biology found that hunting is “by far” the most severe immediate threat to wildlife across Southeast Asia.
“Hunting is the first priority that we have to tackle,” agreed Rungnapa Phoonjampa, a gibbon researcher working with WWF Greater Mekong in Thailand. Hunting “just kills off the gibbon life cycle, because they are very slow to recover”. Gibbon pairs typically only produce one infant at a time, with the young staying with the mother for at least two years. As a result, the poaching of mature individuals has compounded the rapid rate of decline.
“In the past we used to hear [the gibbons singing] a lot, but now we don’t hear them so much. I think it’s people going into the forest to log that is affecting them,” said Surat Monyupanao, head ranger at Thap Lan National Park, who has served there 25 years.
Collateral damage in a deadly trade
Unfortunately, no one knows precisely what impact the hunting of Pileated gibbons in Thailand’s parks is having on populations. Incursions of Siamese rosewood loggers spiked between 2012-2014, but rangers report that the poaching continues unabated.
Last year, camera traps laid in Thap Lan by the Freeland Foundation, a conservation NGO that has been working in the park for eight years, documented a 950 percent increase in poacher numbers over just a single three month period.
Photographic evidence gathered by Thap Lan’s rangers further depicts the deadly results of the poachers’ activities, damage which reverberates throughout the lowland dipterocarp tropical forest ecosystem. It’s likely that the loggers engage in opportunistic hunting of the gibbons. They are relatively easy to shoot, especially when singing.
“When the poachers go into the forest, they can get everything — gibbons are just one species — but all other species are targeted too,” reported Phoonjampa.
Tracking the illegal loggers down and capturing them is no easy task. The poachers trek for days into the forest to access rosewood trees deep inside the protected areas, which coincidentally is where the most gibbons are also to be found. The loggers aren’t to be trifled with: they can be well armed, and regularly engage in firefights with Thailand’s understaffed and under-equipped wildlife rangers.
The gibbons and other wildlife hunted as bushmeat by the poachers are biological fallout at the start of the rosewood supply chain — a lucrative black market trade that saw US $2.4 billion worth of the ‘Hongmu’ (red wood) timber imported from the Mekong region to China between 2000 and 2014, according to the Environmental Investigation Agency (EIA).
Curbing the rosewood trade
While Siamese rosewood was listed under the Convention on Trade in Endangered Species (CITES) in 2013, systemic corruption and legal loopholes have allowed the brisk Southeast Asia black market trade to continue.
Some good news: The CITES Conference of the Parties in 2016 helped to close one of those loopholes. Annotation 5 — which restricted CITES controls to just the sale of “logs, sawn wood and veneer sheets”, and allowed the trade of any other “semi-finished” products without the need for export permits — had opened the door for illegal logging and has now been deleted, But it remains to be seen how this policy change will filter down to life in Thailand’s forests.
“Yes removing Annotation 5 will help, but [rosewood] will still be completely logged out unless China doesn’t help [from] the demand-side. As long as there is the money there to be invested in the trade, there will be [poachers] willing to be involved”, said Prawatsart Jantorntep, Director of Thap Lan National Park.
“People need to know that the [wildlife poaching] problem starts with rosewood,” agreed Kasidis Janpradub, a law enforcement officer based at Thap Lan. “The Chinese community should know that the [rosewood] demand side lies with them, and they should realize there’s a war here in the forest, and for now, it never ends.”
“The poachers are poor, and they know that if they come into the forest here for fifteen days, they can feed their family for a month,” Janpradub explained, adding that the poachers “are just following the instructions of the people with money who send them.”
In June 2015, Thailand’s Department of National Parks, Plants and Wildlife formed an elite group of forest rangers, called Hasadin, specifically tasked with curbing violent Siamese rosewood poaching across the country.
Chasing up-to-date information
All gibbon species are globally threatened with extinction, and a lack of up-to-date, comprehensive population and ecological data undermines efforts to conserve them.
In Southeast Asia, scientists’ efforts to survey gibbons are being rapidly outpaced by widespread habitat loss, fragmentation, and degradation, hunting, as well as the capture of these small apes for the pet or tourist trade.
“It’s time to re-evaluate the Pileated gibbons’ status due to the rapidly changing situation across their range,” said Tim Redford, a training coordinator at Freeland.
The last census survey done in 2005 across Southeast Thailand found approximately 14,000 Pileated gibbons, with approximately 12,000 living in the four largest contiguous forest area complexes. But no one knows what those numbers look like today.
The authors of the 2005 study, published in the journal Oryx, attributed the low numbers of Pileated gibbons in areas far from protection units to poaching, and suggested that their number is 25-50 percent lower than what they would be in the absence of human disturbance. The researchers also believed that hunting had replaced deforestation as the greatest threat to Thailand’s Pileated gibbons by the end of the 20th century.
But the lack of current population data “makes it impossible to respond to recent or current threats,” reported Warren Brockelman, a gibbon researcher and conservationist who has worked in Thailand for more than four decades.
The sheer pace of habitat destruction in nearby Cambodia — long considered the stronghold for Pileated gibbons — has meant that up-to-date population counts there for this primate are also non-existent.
“Things are changing very quickly, and the protected area system is not very stable. Conservationists are not in control of the situation,” said Brockelman. A 2005 report published by Flora and Fauna International estimated that 35,000 Pileated gibbons then remained in Cambodia. But that was 11 years ago, and numbers have surely dropped since then. Large agribusiness concessions have transformed large swaths of Cambodia’s remaining habitat, converting its intact deciduous dipterocarp forest — known as the Central Indochina Dry Forest Ecoregion — into cropland.
One approach that is having some success in Cambodia is the direct engagement of forest communities in conservation using new technologies, such as SMART (Spatial Monitoring and Reporting Tool), an effective method for patrolling and practicing law enforcement in protected areas.
There may be some hope for gibbon recovery in Thailand too, according to Brockelman. The country’s intact forests still have the “carrying capacity” for much larger Pileated gibbon populations. Examining the correlation between gibbon density and forest characteristics, Brockelman and other scientists have found that the two main predictors of abundance of gibbons in Thailand’s wild areas are the percentage of evergreen forest cover and distance from a boundary or road.
“If we [had] an update on the [current] number of gibbons, it might help [us] identify which [geographical] areas to focus our attention on to do intensive patrolling, or [where to] start increasing our conservation activities in order to save this species,” said Phoonjampa. “I would like to do a [new] survey to gauge how the Pileated gibbon population is faring, but it is difficult to get funding to research species that are not considered iconic, like the elephant or the tiger.”
Unfortunately, the presence of armed Siamese rosewood poachers makes such an updated survey highly unlikely, at least for the time being. Auditory surveys to calculate gibbon population density usually require two to three researchers walking deep into national park forests, camping out for days, and following and recording the gibbons’ calls as the animals move through the treetops. “it would be pretty dangerous, and I just don’t think it would be safe in Thap Lan to do that now,” concluded Redford.
Correction: A previous version of this article stated that “US$1.2 billion of rosewood timber was illegally smuggled into China between 2000 and 2014”. This has been corrected to “Hongmu’ (red wood) timber imports from the Mekong region to China between 2000 and 2014 were valued at nearly US $2.4 billion.”