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Long-tailed macaque surrounded by trees

The UK Is Failing Long-Tailed Macaques

There are worrying shortcomings in the U.K.'s oversight of long-tailed macaque imports, a species that is extensively exploited in trade to satisfy the insatiable demand from laboratories for test subjects.

Long-tailed macaques are the most heavily exploited mammals on Earth among species protected in global trade, in terms of sales of live individuals, according to figures from the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). 

Overall, exporting countries reported over a million long-tailed macaque trades between 2016 to 2021. These included sales of their body parts and specimens, such as blood and tissue, as well as live individuals. 


For years, concerns have circulated over whether trade in the species is sustainable. At a meeting in June 2023, CITES, which regulates international trade in the primate and many other wild species, agreed to review the trade from some exporter countries due to this.

However, the U.K.’s trade records, along with government responses to queries about imports, suggest that countries buying the primates also require scrutiny. They point to a lack of rigorous checks and balances at the receiving end of the long-tailed macaque supply chain.

The International Union for Conservation of Nature's Red List classified long-tailed macaques as endangered in 2022. Habitat loss and persecution play a significant role in their situation, as does high demand of the primates in trade, primarily for use in research. 

Long-tailed macaques are the go-to primate for regulatory toxicity testing in laboratories, meaning they are utilized in the manufacture and testing of drugs and other substances. 

According to research published in 2022, exporting countries reported trading over 476,000 live individuals between 2010 and 2019, with a market value of around $1.25 billion.  


The U.S. is the biggest importer of long-tailed macaques, with other major buyers including the EU, the U.K. and Japan. A study published in April highlighted that in the space of 20 years up to 2021, the EU and U.K. imported between 218,000 and 238,000 live primates, mostly long-tailed macaques.  

It’s critical that trade records involving macaques are thorough and accurate to assess the sustainability of trade. However, as researchers have highlighted, CITES’ own data on trade in live long-tailed macaques contains large discrepancies, with figures that exporting and importing countries report rarely matching. 

This is partly due to CITES’ differing species-dependent permitting requirements for countries at either end of the trade chain.  

Moreover, it’s impossible to know how many individuals are utilized in the number of specimens traded, such as blood and tissue, because CITES doesn’t require countries to report this. Specimens make up the bulk of reported trade in long-tailed macaques in CITES’ records.

The situation makes scrutiny of the trade difficult, according to The Long-Tailed Macaque Project's Malene Hansen. “The discrepancy level is through the roof,” she says. “We are trying to monitor here but we actually don't know exactly what's going on.” 


The U.K.’s national trade records, along with responses to queries and freedom of information requests from relevant government agencies, show that such inadequacies are not limited to CITES data.

The U.K.’s customs authority, HMRC, maintains a national information hub on trade, the U.K. Trade Info database. It points to an increasing number of live primates imported in recent years, with import “units,” meaning individual primates, rising from 898 in 2016 to 2,255 in 2022.

Although HMRC’s data lacks detail on the species involved, the U.K.’s reported figures to CITES during the period indicates that the imports were overwhelmingly of long-tailed macaques. 

The Trade Info database also shows a steep rise in the reported weights of primate imports in recent years. In 2022, the data suggests that the average weight of imported individuals was over 9.5 kilograms, compared to averages ranging from 2.7 to 3.7 kilograms between 2016 and 2020. High average reported weights have continued in 2023.

The listed weights relate solely to the primates themselves and do not include the crates they travel in or other transport materials, according to HMRC. 


Although weight listings for live animals in trade reports may seem like a relatively minor detail, their inclusion can be valuable. Weights can point to potentially illicit activities, like smuggling, and trade trends, such as the approximate age of imported individuals. 

Non-human primates as a group include apes, monkeys and prosimians, such as tarsiers. The larger species can weigh anywhere from around a dozen kilos, such as some baboons, to 200 kilograms, like gorillas. 

Long-tailed macaques are comparatively lighter even when full grown. However, the preferred age of macaques for toxicology testing is usually around 3 years old, when they would weight between 2.5 and 3 kilograms, according to Action for Primate's Sarah Kite. 

Given that long-tailed macaques represented most of the primate imports recorded by the U.K., such a high average weight would be highly abnormal, she says. 

Meanwhile, according to analysis provided by the group Abolición Vivisección, Spain’s national data, where several imports came from in 2022, conflicts with U.K. records. 


According to the Trade Info database, the average weight for recorded imports from the country was almost 10 kilograms, whereas Spain’s apparent records for those trades puts the average at around 4 kilograms. 

Asked about the abnormally high average weight records and increasing imports, the Department for Environment, Food and Rural Affairs (DEFRA) advised a degree of caution in drawing conclusions about trade trends. 

This is due to the country’s data being affected by its exit from the EU and shipment reporting changes in 2019, according to the department. In sum, it’s unclear why U.K. data lists increasingly high weights for imports but the discrepancies between the U.K. and Spanish data could point to a recording issue of some kind. 

Born Free’s head of policy Mark Jones finds these disparities in the trade concerning. "There always seem to be huge discrepancies between export and import data in these kinds of transactions, which is clearly unacceptable given we're talking about numbers of live animals," he said. "The very least that should be expected is for the counts to be accurate and consistent.” 

Jones added: "If the data the U.K. is collecting does not enable meaningful trend analysis, you have to wonder what its purpose is.” 


Understanding trends in the long-tailed macaque trade is particularly important at present because trade patterns have changed in recent years. As a 2023 study highlighted, China used to be a dominant supplier of live macaques globally. It predominantly exported captive-bred individuals, which purportedly make up most of the live trade. 

According to the Species Survival Network — a coalition of wildlife nonprofits — more than 70% of live long-tailed macaques traded between 2011 and 2020 were alleged to originate from captive-bred facilities. 

CITES records show China’s exports have dropped off since 2019. To fill the void left by the country, other nations, such as Cambodia, have increased their exports of reportedly captive-bred individuals.  

Hansen, who was the lead researcher for the macaque’s IUCN assessment, provides an example. She explains that one Cambodian farm tripled its exports, from 4000 to 12,000, between 2019 and 2020. 

With females only giving birth to one offspring every one to two years, along with 2- to 3-year-old juveniles being most sought after for medical research, such “extreme increases are not possible” in captive-bred operations, she says.


The rapid increases in exports from certain countries have increased concerns that captive breeders may be overexploiting wild macaques to restock their breeding populations and laundering wild individuals into the captive-bred trade. In April, the EU released a report that provides some further context for these concerns. 

Relaying information from overseas captive-breeding operators, the report highlighted that “the rise in demand is currently using all the purpose-bred animals produced by the breeders, leaving no non-human primates for replacement of breeding animals which are coming to the end of their effective reproductive life.”  

Considering all these moving parts, weights and other aspects of trade reporting could be instructive in terms of identifying trends and potentially illegitimate practices. 

The UK government insists that it has robust processes in place, including close monitoring and a strict licensing system, to ensure its trade in long-tailed macaques and other primates is sustainable.

A DEFRA spokesperson said: “The U.K. controls go above and beyond those required by CITES to include import permits for all species that may become threatened with extinction through international trade, which means that assessments of sustainability must be conducted by UK authorities before any import of primates is authorized.” 


As the spokesperson indicated, the backbone of CITES-regulated trade is a permitting system, with varying permit requirements depending on the conservation status of species. 

But the response to a freedom of information request to DEFRA’s Animal and Plant Health Agency (APHA), which is the U.K. CITES Management Authority, suggests the government itself does not consider this system wholly reliable. 

Following the FOI request, APHA provided figures for imports of long-tailed macaques in 2021 and 2022. The agency cautioned that it could not “guarantee the accuracy” of the data, due to the agency being reliant on information “that has been input into external customer facing systems by third parties.” 

APHA emphasized that the provided information “is a true reflection of the information that we have access to.” Ultimately, this warning turned out to be prescient as it materialized that the agency had itself provided incomplete data due to an administrative error. 

Kite says APHA’s warning raises questions over whether the U.K. has mechanisms in place “to check and compare the actual imports of primates against the numbers submitted on a CITES permit.” 


Border checks are a mechanism for authorities to check actual live imports against the associated paperwork, such as CITES permits and veterinary health certificates. 

Varied communications with DEFRA and Border Force, the entities involved in such checks, indicated that all live imports are checked at the border, which can involve paperwork, identity, and physical checks, along with tests.

However, physical inspections appear to take place on a case-by-case basis, based on different factors, such as assessments of risk. This is in line with the treatment of other "goods" that the U.K. imports, according to DEFRA. Wildlife trade investigator Daniel Stiles says physical checks in other destination countries are not always guaranteed either. 

He authored a report on the trafficking of non-human great apes in April that illustrated why physical checks at borders are vital. The report highlighted that the smuggling of great apes takes place “using concealment and mislabeling of documents.” For instance, they “may be shipped with CITES permits indicating other species”, such as birds or other primates.  

Kite says “the lack of mandatory physical inspections of non-human primates at the border is alarming for welfare and public health reasons.” Jones also argues that UK authorities “should be inspecting each and every consignment of live macaques” to fulfil their various legal duties. 

Nevertheless, the DEFRA spokesperson commented: “We are fully committed to the implementation of the CITES Convention, with parts of the U.K. system being described by the United Nations Office on Drugs and Crime as international best practice.” 


At a CITES meeting in June, the U.K. joined with other nations in agreeing a U.S.-led recommendation to review the captive-bred supply of long-tailed macaques from several source countries, namely Cambodia, Indonesia, Vietnam and the Philippines. In essence, the review will probe the credibility of captive breeding facilities, putting source countries under the spotlight.  

Hansen welcomes the CITES review. But she stresses that importing countries must be held to account too. Referring to the changing trade patterns, she argues that importers “know that a country that used to export a certain amount can't suddenly export numbers that are 10 times as high.” 

In short, authorities across the supply chain need to take responsibility for ensuring trade is legitimate and sustainable. 

This is only possible if they have rigorous and trustworthy systems in place to ensure that oversight of the trade is robust. With the long-tailed macaque’s now endangered status, the stakes for the most heavily exploited mammal in CITES-regulated live trade couldn’t be higher. 

This story was produced with support from Internews' Earth Journalism Network. It was first published in The Ecologist on November 17, 2023. It has been lightly edited for length and clarity and is republished here published under a Creative Commons 4.0 license. 

Banner image: A long-tailed macaque at Fraser's Hill, Malaysia / Credit: Peter Gronemann via Wikipedia Commons (CC BY 2.0).