Action for Primates
As human beings expand into and destroy natural habitat, there is a concomitant increase in interactions with non-human primates. Historically, this has been defined as 'conflicts', a pejorative term that is based on an anthropocentric view of the issue. It is important to understand, however, that activities by non-human primates considered undesirable by people are not the result of purposeful behaviour against people. The non-human primates are only trying to survive in an increasingly diminishing and hostile environment due to human activity. They are not 'crop raiding' nor are they 'competing'; rather, they are being forced to overcome their innate fear of people in order to survive by foraging on whatever is available. Our language, therefore, should not only be free of negativity and be sensitive to the plight of the non-human primates, it should also imbue a sense of hope and optimism for resolution that emphasises the interests of all concerned.
In an effort to resolve the problems created by themselves, people will often use methods that are inhumane and ineffective. Large numbers of non-human primates may simply be rounded up and killed. Others may be captured alive and used for research and breeding or for the 'pet' and food trade. Although this may provide a short-term reduction in animal numbers, it is cruel and fails to address the issue over a longer period of time. The large scale trapping and exportation of monkeys for the food and research industries is also inhumane. Moreover, this has been shown to be largely ineffectual in reducing damage to human property and crops or in reducing the number of individuals long-term. For example, despite the trapping and export for research of 10,000 vervet monkeys over a 14 year period in Barbados, this did not have the desired effect of reducing crop foraging, as the population of monkeys remained stable due to the species' high breeding rate [§, §].
Complicating this issue is the mistaken belief that free-living (wild) non-human primates are a threat to human health due to transmission of diseases. There is also considerable misinformation about what diseases monkeys carry in general and which might be transmissible to human beings, although there is also a significant risk of disease transmission from people to non-human primates in captivity. There is very little likelihood that free-living non-human primates could transmit any disease to human beings, unless they are brought into close contact with people such as being trapped for the research or 'pet' trade or to be killed as food.
The issue needs to be approached from at least two perspectives. One is changing public behaviour and perception, the other is implementing practical methods that are effective.
Preventive measures: It is essential that people involved with management methods understand that adverse interactions between wild animals such as monkeys and people are usually due to inappropriate behaviour on the part of human beings, not the other animals. Wild animals are typically fearful of human beings. If, however, people feed or in any way tolerate or encourage the presence of the animals, the animals become less fearful. Feeding can also make the monkeys reliant on a human food source (anthropogenic), causing them to spend less time foraging for natural sources of food and can artificially increase 'carrying capacity', causing an increase in reproduction beyond what natural habitat would dictate. It is critical, therefore, that people be taught not to encourage the animals in any way. This includes not only not feeding the animals or having easily-available food sources, but also not making attempts at being 'friendly' with the monkeys.
Educating residents to make changes to their lifestyle will be necessary. Monkey-proofing their trash receptacles and deterring entry into their homes through the use of suitable window screening are essential. Food or garbage must not be allowed to accumulate anywhere the monkeys can have access to it. People must be discouraged from feeding wildlife. For example, in Hong Kong and Singapore, fines are imposed against those people who continue to feed wild monkeys.
A systematic method of scaring away the animals with things like unnatural sounds or the sounds of their predators should be instituted and used consistently every time there is an intrusion. For example, in some communities, specific people are assigned the duty of chasing away monkeys from residential or other areas [§, §]. The same principle can be used for deterring crop foraging [§, §, §]. In some cases, dogs have been used successfully to guard fields of crops or deter monkeys from entering areas of human habitation. Solar powered electric fencing can be economical and effective in reducing access to crops. Another strategy involves the use of laser pointers or taste aversion.
Sterilisation: Sterilisation is an effective long-term solution that ensures there will be fewer and fewer monkeys over time. It is increasingly being used by authorities who recognise its importance to humanely and effectively provide long-term resolution [§, §, §, §, §, §, §, §, §, §]. It should be understood, however, that sterilisation will take time to reduce the number of monkeys in order to result in reduced interactions. Because of this, people would still have to do what they could to discourage monkeys. Importantly, sterilisation should only be used for finite situations, not as strategy for overall management.
As for the method of sterilisation, because the monkeys are completely free-living, the most effective method would be to remove the ovaries (ovariectomy) of females, tie off their Fallopian tubes (tubal ligation) or remove part of the Fallopian tubes (salpingectomy) (Deleuze et al 2021, Yu et al 2015). Once done, these methods would ensure that the female would not be able to reproduce. Although easier to do, sterilising the males will be less effective than doing the females, whether surgically or with vaccine, as it will only take one fertile male to impregnate perhaps several dozen females.
Another way to sterilise females (and males) is the use of chemical or similar sterilants. One is GonaCon™, a gonadotropin-releasing hormone immunocontraceptive vaccine developed by USDA-APHIS-Wildlife Services. It has been shown to be effective in a variety of species. There is some evidence that it may be effective in non-human primates[§]. It has to be injected into the individual, so trapping is still necessary.
Another is Reversible Inhibition of Sperm Under Guidance (RISUG). This contraceptive was developed for human males, but is being advocated for use in non-human primates. It appears to provide lifelong sterilisation.
As with any sterilisation procedure, a method of permanently marking the animal who has been done has to be instituted in order to prevent duplicative efforts. Also, if a vaccine is used, a means of identifying the animals based on when they were done has to be developed in order to know not only that an individual has been done, but also when it is time to re-vaccinate.
Coexistence: In addition to the above, careful consideration of all the issues may lead to discoveries that allow for reasonable coexistence. For example, in Indonesia, it was found that monkeys and human beings depended on the same native tree and that cultivation of this tree might not only help the ecosystem, it might result in a reduction in crop foraging. In South Africa, crop-foraging baboons could be deterred by planting crops specifically for them some distance from the farm.
Trapping and relocation: This may not be ideal or effective in all situations. Success with this approach depends on having suitable habitat located a sufficient distance away to deter the monkeys from simply returning to the original site. There is no distance that has been shown to ensure their not returning, but perhaps a location at least several kilometres away might be helpful. The area to which the monkeys are to be re-homed would not only have to be suitable for them in terms of food and shelter, it would also have to be free of other similar monkeys, or else they or the other monkeys will simply be chased away. Such a translocation of monkeys took place in India in 1997, when 600 rhesus macaques were successfully moved to different sites following an increase in monkey-human interactions that were deemed unfavourable.
Although there is no easy solution to the problem, a continued commitment by the relevant authorities will be essential in developing a plan that works, is humane and is sustainable. A multi-prong approach is likely to yield the best results.
With the deployment of the dogs, the number of wild monkeys spotted in residential areas has sharply dropped, according to the city. Dogs of any breed can be placed in a five-month training session after a trainer deems them capable. They must learn not to injure people, chase only monkeys and return to their owners when called.
Worldwide, primates, and humans increasingly share habitats and often enter in conflict when primates thrive in human-dominated environments, calling for special management measures. Reproductive control is increasingly used to manage population growth but very few monitoring data are available. … In the context of a contraception program in wild female long-tailed macaques in Ubud, Bali, conducted over four successive campaigns between 2017 and 2019, including 140 females (i.e., 41.9% of the reproductive females of the population in 2019), modifications of an endoscopic tubectomy procedure, a permanent sterilization method, clinical evaluation of this method, and the post-operative monitoring results of the neutered females after release are described. … Moreover, no new pregnancies in sterilized females were recorded during the 3-year observation period. The survival rate of the treated females 6 months after sterilization was high (96.3%) with no major post-operative complications clinically recorded. Among females that were pregnant during surgery, 81.1% were confirmed to experience term delivery. This study demonstrates the safety and efficiency of endoscopic tubectomy, even for pregnant females, as a mean of wild macaques' population control.
A three-year sterilization program using female endoscopic tubectomy was launched in 2017 to manage the macaque population growth and allowed the sterilization of 136 females in the population…
Contraception is increasingly used to control wild animal populations. However, as reproductive condition influences social interactions in primates, the absence of new offspring could influence the females' social integration. We studied two groups of wild macaques (Macaca fascicularis) including females recently sterilized in the Ubud Monkey Forest, Indonesia. … These results confirm the influence of nursing condition in female macaque social networks and did not show any negative short-term effects of sterilization on social integration.
It just reduces the troop size for a little while.
The feeding and release of wildlife has been made illegal islandwide with sweeping changes to the Wild Animals And Birds Act passed in Parliament yesterday that confers greater protection on Singapore's native flora and fauna.
Our results suggest that field rangers are a successful nonlethal method for reducing spatial overlap between baboons and urban areas but that intensive, unsystematic herding of the troop does have measurable impacts on behavior and should be prevented.
An increasing number of studies have found that the implementation of feeding sites for wildlife-related tourism can affect animal health, behaviour and reproduction. Feeding sites can favour high densities, home range overlap, greater sedentary behaviour and increased interspecific contacts, all of which might promote parasite transmission. In the Yunnan snub-nosed monkey (Rhinopithecus bieti), human interventions via provisioning monkeys at specific feeding sites have led to the sub-structuring of a group into genetically differentiated sub-groups. The fed subgroup is located near human hamlets and interacts with domesticated animals. … These elements suggest that feeding sites might indirectly play a role on parasite transmission in the Yunnan snub-nosed monkey.
Periods of development and economic boom have meant that the baboons' natural habitat has often been invaded. This continuous sabotage over the course of many years excessive logging, destruction of forests, and the killing of natural predators such as tigers, hyenas, wolves, and lynxes led to the rise of the "monkey phenomenon" in different regions of the Kingdom. They began to flee from the natural areas in which they lived to agricultural areas, attacking the livelihood of farmers.
[Ahmed Al-Bouq, supervisor of the national launch program and the research and breeding centers of the National Center for Wildlife, stated that] …killing the animals was not a viable solution, stressing the important issue of maintaining ecological balance.
When these animals are fed by humans, they often develop a dependency on humans as a source of food and become territorial over the area where feeding occurs. This dependency can lead to increased aggression, which may result in injuries and spread of disease to humans.
Male macaques were more likely to co-interact with humans than females. Neither macaques' grooming relationships nor their dominance ranks predicted their tendencies to co-interact with humans.
Our findings suggest that, in challenging anthropogenic environments, less (compared to more) time-consuming forms of affiliation, and additionally greater social tolerance in less ecologically flexible species with a shorter history of exposure to humans, may be key to animals' joint propensities to take risks to gain access to resources. For males, greater exploratory tendencies and less energetically demanding long-term life-history strategies (compared to females), may also influence such joint risk-taking. From conservation and public health perspectives, wildlife connectedness within such co-interaction networks may inform interventions to mitigate zoonosis, and move human-wildlife interactions from conflict towards co-existence.
…across all species, males and spatially peripheral individuals interacted with humans the most, and that high-ranking individuals initiated more interactions with humans than low-rankers. Among bonnet macaques, but not rhesus or long-tailed macaques, individuals who were more well-connected in their grooming network interacted more frequently with humans than less well-connected individuals. From an evolutionary perspective, our results suggest that individuals incurring lower costs related to their life-history (males) and resource-access (high rank; strong social connections within a socially tolerant macaque species), but also higher costs on account of compromising the advantages of being in the core of their group (spatial periphery), are the most likely to take risks by interacting with humans in anthropogenic environments.
Increased edge density around households, collection of small trees for construction, and foraging and hunting for food in forested habitat significantly increase the likelihood of human-NHP contact.
As animals increasingly occupy habitats in proximity to humans, with home ranges a mosaic of natural and anthropogenic landscapes, it becomes imperative from a conservation perspective to understand the impacts of human activities on wildlife. … Such proximity, however, is often accompanied by direct conflict between humans and wildlife, leading to higher stress levels, injuries, mortality and behavioural changes, with detrimental effects on long-term health and fitness. … Taken together, the results of this study highlight the risks associated with ranging in anthropogenic environments and point to the need for a multifaceted approach to studying the negative impacts of human activities on animals so as to better inform conservation practices.
This study highlights the risks of roads for monkeys, and that collision rates vary with species, age class, and, in some species, sex and that rainfall is one factor that affects these rates.
With the uncontrolled expansion of anthropogenic modifications of the environment, wildlife species are forced to interact with humans, often leading to conflict situations that have detrimental effects for both wildlife and humans. … Access to human-origin food, either cooked or packaged, acquired directly from homes or garbage pits, in the human-dominated habitat appeared to significantly reduce active foraging and searching for food…
We recommend that efforts to protect Buton macaques focus on education and the use of effective nonlethal mitigation techniques, such as electric fencing.
Here I briefly outline current debates about the use of terms such as human–wildlife conflict and crop raiding and why they are misleading, summarize current knowledge about primate crop foraging behavior, and highlight some key areas for future research to support human–primate coexistence in an increasingly anthropogenic world.
In Nepal, for example, the expansion of monocultures, increased forest fragmentation, the degradation of natural habitats, and changing agricultural practices have led to a significant increase in the frequency of human-macaque conflict. … As human-macaque conflict is one of the most critical challenges faced by wildlife managers in South Asia and Southeast Asia, studies of macaque crop raiding behavior provide an important starting point for developing effective strategies to manage human-macaque conflict while promoting both primate conservation and the economic well-being of the local community.
Crop type and distance from farm fields to the forest edge affected crop raiding. Planting buffer crops and collective monitoring are recommended to reduce crop loss. A program of natural forest restoration is needed in rural areas of Nepal.
Contact with human beings or habitat altered by them may lead to reverse zoonosis and compromise the health of non-human primates.
Around the Uluwatu Temple in Bali, Indonesia, a large free-ranging population of long-tailed macaques spontaneously and routinely engage in token-mediated bartering interactions with humans. These interactions occur in two phases: after stealing inedible and more or less valuable objects from humans, the macaques appear to use them as tokens, by returning them to humans in exchange for food. Our field observational and experimental data showed (i) age differences in robbing/bartering success, indicative of experiential learning, and (ii) clear behavioural associations between value-based token possession and quantity or quality of food rewards rejected and accepted by subadult and adult monkeys, suggestive of robbing/bartering payoff maximization and economic decision-making.
This study provides the first indirect evidence that some Peninsula baboons with a history of raiding human food sources, may be at risk of developing insulin resistance in the wild, with long term implications for population health.
Anthropogenic influence is expanding, threatening primate taxa worldwide. With wildlife tourism a burgeoning industry, understanding human–primate interactions is key in avoiding primate defaunation. We observed interactions between humans and a group of wild Panamanian white-faced capuchin monkeys (Cebus imitator) at Curú Wildlife Refuge, Costa Rica, in June and July, 2019, and compared our findings with findings for the same group in May–October of 2006 and 2007, when the group received more provisioning. … The reduction in moderate and intense behaviors between studies also suggests that reducing direct provisioning could reduce the frequency and intensity of human–primate interactions in tourist sites.
Primates exhibit behavioral flexibility in anthropogenic habitats in various ways, most commonly documented as dietary adjustments, i.e., incorporation of human foods including agricultural crops and provisioned items, and as differences in activity, ranging, grouping patterns, and social organization, associated with changing anthropogenic factors. … The contributions to this Special Issue include both empirical research and reviews that examine various aspects of the human–primate interface. Collectively, they show that primate behavior in shared landscapes does not always conflict with human interests, and demonstrate the value of examining behavior from a cost–benefit perspective without making prior assumptions concerning the nature of interactions.
Despite concern about environmental protection, travelers often underestimate the contribution they may have to disease transmission to other species, as well as the risk of becoming infected themselves. … Results revealed that even though individuals with more positive environmental attitudes were more willing to take steps to mitigate tourism-related disease transmission, they were also more likely to report wanting to touch or feed a monkey/ape. … The human desire for physical contact with other species may be partly the result of biophilia, emotionally arousing events (like contact with exotic species) that can lead to further disinhibition, and social media platforms that provide opportunities for exhibitionism. … Individuals for whom physically interacting with monkeys/apes may be emotionally rewarding may not alter their behavior in response to cognitive means of persuasion; techniques aimed at appealing to emotions may be more effective.
Critical information on two novel zoonotic viruses is presented, unique Indian macaque Simian Foamy Virus (SFV) and H1N1 Influenza A viruses (IAV)-like virus infecting wild rhesus monkeys from the Rajasthan forests. Monkey bites are quite common in India.
The data presented here however indicate a reverse transmission of H1N1 IAV from humans to rhesus monkeys…
Reducing animal-human contact and affordable vaccination are two relevant anti-viral strategies to counteract the spread of infectious zoonotic pathogens.
We surveyed 794 people co-living with four different primate speciesrhesus macaque Macaca mulatta, bonnet macaque Macaca radiata, lion-tailed macaque Macaca silenus, and Hanuman langur Semnopithecus dussumieriin southern and western India to understand how people perceived the costs and benefits of coexistence. The results of our semi-structured interview study revealed that although tangible costs (i.e., financial losses from primate depredation) primarily drive people's stated tolerance for primate presence, intangible benefits from primates (i.e., their ecological, existence, sentience, and religious values) also critically affect attitudes towards coexistence. Amongst the four species, people associated rhesus macaques with the greatest costs and fewest benefits, lion-tailed macaques with the lowest costs, and bonnet macaques with the highest benefits. People preferred lion-tailed macaques and Hanuman langurs more than bonnet and rhesus macaques, and affection for a species shaped how people viewed costs accruing from the species. People's preferences for species were influenced by their existence, ecological, and sentience values more than their religious value. We suggest that intangible benefits influence people's fondness for a primate species and this, in turn, shapes how people perceive costs resulting from the species. Hence strengthening people's perceptions of the intangible benefits they receive from primate species will improve human tolerance for living near primates. We argue that there is a need to understand the context of human–primate conflicts beyond the cost aspects and focus on the benefits to improve human–primate coexistence.
The macaques appear to be attracted to the road because it presents opportunities to obtain palatable and energy-dense foods. Our results indicate that moor macaques are able to flexibly adjust their ranging behavior in response to anthropogenic impacts. However, given the risks of being in proximity to roads and humans, management of this emerging human-macaque interface is needed.
Several species of Costa Rican wildlife are suffering terrible injuries along the power lines in rural areas of the country due to the increasing human development in rural areas, but this has also brought the problem of poorly designed electric infrastructure, where arboreal mammals find their normal tree routes cut down so that the only way for them to cross is on the power lines where they can get electrocuted.
Provisioning of primates is a common behavior that humans engage in at these sites. … People were driven to feed macaques by the desire to observe them closely, concern over decreasing food resources for wildlife, and religious affinities.
We found that the macaques' consumption of natural resources and dietary diversity decreased, and they spent more time in human-modified habitats when provisioned food was available. We also found that particular behaviors of the provisioned macaques stimulated provisioning by humans. Our findings show that provisioning influences macaque feeding ecology and habitat use, and that the behavior of the macaques themselves drives people to provide them with food subsidies, illustrating a complex web of interactions between the sympatric species.
The aim of the manual is to describe methods that farmers can try to reduce crop damage, not to describe methods to reduce monkey numbers.
The Green monkey (Chlorocebus sabaeus) was first introduced to Barbados in the early 1600's, and an Act for Destroying Wild Monkeys and Raccoons was passed for the first time in 1680 because of their crop raiding behaviour. The monkey population has risen and fallen several times since the bounty was introduced, but a recent increase in crop raiding activity has been creating significant challenges for the agricultural sector.
Crop fields were avoided for most of the year, suggesting that fields are perceived as a high-risk habitat. When field visits did occur, this was generally when plant primary productivity was low, suggesting that crops were a “fallback food”. All recorded field visits were at or before 15:00. Activity was significantly higher in crop fields than in the landscape in general, evidence that crop-foraging is an energetically costly strategy and that fields are perceived as a risky habitat. In contrast, activity was significantly lower within 100 m of the field edge than in the rest of the landscape, suggesting that baboons wait near the field edge to assess risks before crop-foraging. Together, this understanding of the spatiotemporal dynamics of crop-foraging can help to inform crop protection strategies and reduce conflict between humans and baboons in South Africa.
We found that 16 of 21 (76%) primate species in China, for which data are available, have experienced a population decline over the past 35 years. Factors contributing most to primate population decline included human poverty and the conversion of natural habitat to cropland. In contrast, the five species of primates that were characterized by recent population increases were the subjects of substantial government research funding and their remaining distribution occurs principally in protected areas (PAs).