The Kayan River slow loris has been assessed as Vulnerable by the International Union for Conservation of Nature (IUCN, 2015), appearing on IUCN’s Red List of Threatened Species. The species is suspected to be in decline due to loss of habitat from deforestation, forest fires, and the illegal pet trade.

Burning of habitat and forest conversion, especially to palm oil plantations, represent threats to the species. Because the Kayan slow loris is relatively adaptable to human settlements one might assume that the species could be less affected by forest loss than some other primate species. However, the severity of deforestation in general and recent forest fires specifically have had dramatic impact on the region and its inhabitants, including the Kayan slow loris. 

Kayan slow lorises are collected locally for use as pets. Subsequent uncontrolled release of pets in some areas is also a threat. Hybridization poses a real threat to this species both in the wild and among confiscated individuals in rescue centers. In addition, the species is at risk of exploitation in the illegal wildlife trade. Lack of law enforcement further threatens slow loris species across their range.

Until the late 2015 assessment of the species, which was only announced in the summer of 2020, the Kayan River slow loris was considered a subspecies of the Philippine slow loris whose 2008 IUCN evaluation deemed them Vulnerable. With the recognition of several new slow loris species native to Borneo since that time—all of which were once also considered subspecies of the Philippine slow loris—it is likely that each species’ population is in more critical condition than previously thought.

This taxonomic saga sheds light on the risks of unintentionally misrepresenting species based on insufficient data. When species are more biologically diverse than science previously assumed, it takes years for conservation efforts to catch up. In that time, the situations in which those previously unrecognized species find themselves are likely to grow more precarious.

Indeed, misunderstanding the taxonomy of slow loris species has proven problematic for their conservation both generally and locally. While researchers wrestle with the raw data, conservationists may occasionally misidentify the individual slow lorises that wind up in their care. Since taxonomy determines what they should be fed, how they should be socialized, and where they should be released if they are eventually rehabilitated, proper care and rehabilitation are dependent on proper species identification.

This issue of taxonomy is doubly important given the sheer number of slow lorises that end up in rescue and rehabilitation centers. The biggest threat to all slow loris species is their value as commodities in the exotic pet trade and for traditional medicines. Slow lorises are illegally trafficked and sold all over the world. Buyers rarely have any concern about what variety of slow loris they are receiving. When rescued from these circumstances, a slow loris is inevitably already in rough shape. Suffering from infection, malnutrition, and blindness, and highly stressed by his ordeal, there is no room for error in getting him what he needs as fast as possible. Therefore, proper rapid identification is essential to his rescuers’ success.

Unfortunately, poached from the wild, a slow loris’s chances of survival are small—and rehabilitation leading to her release even smaller. Even if she is properly brought back to optimal health, a single consequence of her ordeal often remains that will permanently prevent her eventual release. When she was first taken, her captors prepared her for sale. By removing her teeth—an incredibly painful procedure typically done without any kind of anesthetic—they prevent her from biting their future owners, which can prove fatal. However, with this one action she, a competent and self-reliant creature, is rendered helpless and dependent for the rest of her life. Without her teeth, she cannot properly eat or defend herself in the wild. And so, ultimately, she has no hope of ever going back.

While life in the wild is certainly preferable to life in captivity, slow lorises who avoid becoming pets are still threatened by human encroachment into their natural habitats. When left to their own devices, slow lorises often prove to be quite adaptable and capable of surviving in suboptimal conditions. In many places where they live, however, forests have been degraded to the point where it significantly and adversely affects their rates of survival—and fragmentation of their ranges inevitably inhibits healthy gene flow between spatial groups. What’s more, such trends put them at even greater risk of being found, captured, and sold into the pet trade.

Kayan River slow lorises live in one of the last and largest stretches of continuous ancient forest left in Southeast Asia. Known as the Heart of Borneo, this vast stretch of forest is less than half of what the island once supported. In the last thirty years alone, illegal logging, the construction of dams and other infrastructure, mining, slash-and-burn agriculture, and many other human activities have drastically depleted Borneo’s wilderness, putting the animals that call it home—including many humans themselves—at great risk.

The Heart of Borneo, for now, remains intact. But these trends have not let up. Compounded with the overarching effects of climate change, the future for the Kayan River slow loris’s home appears bleak. Slash-and-burn agriculture has become especially problematic over the years. With its peat forests and swamps, Borneo is highly vulnerable to fire. When a fire ignites in one of these environments it can smolder invisibly underground for weeks. In the wake of such fires, the scorched soil more easily erodes, preventing the forests from ever recovering. September 2019 saw some of the worst fires on record in Borneo, many of which had been set intentionally in order to clear the land for palm oil plantations. So long as the Heart of Borneo is at risk, so too is the Kayan River slow loris.