Sibling rivalry in wild Chacma Baboons.

Jealousy occurs in Humans when we perceive our relationship with a person important to us is threatened by the actions of someone else. This is a complex emotion, which often manifests in attempts to disrupt social interactions that we find threatening. Whether jealousy is a uniquely Human emotion is less clear, as it can be hard to judge the genuine emotional state of non-Human Animals, at least in part due to the dangers of anthropomorphising behaviours that resemble Human emotional traits.

Non-Human Primates would appear to be a good starting point for those wishing to study jealousy outside our species, but very few studies appear to have been done in this area, and all of those on sexual jealousy in captive Primates held in unnatural conditions.

In Humans, one area which has been extensively studied is sibling rivalry among children. Human mothers are unusual in that they often care for multiple offspring of different ages at the same time, leading to forms of competition for parental attention and resources which do not occur in most Animals. Intense rivalries can develop between child siblings when they perceive that they are being treated differently, sometimes leading to conflicts which extend into adulthood. Such rivalries are most likely to develop when children are the same sex and close in age.

Such rivalries between siblings of different ages have not been studied in non-Human Animals. Instead, research has concentrated on competition between siblings produced in large clutches or broods, where they are part of a group reliant on parental provisioning until reaching independence. There have also been some studies concerning mother-child competition for resources in monotocous species (species that have one young at a time), plus a few studies looking at species in which older siblings cooperate in the rearing of young. 

Monotocous Animals with long child-rearing periods, including many Primates, form an intermediate group between Humans and polytocous species (species that have produce many offspring in a single clutch or litter). In such species different aged siblings interact with one-another and their parent(s) on a daily basis, and competition between siblings has the potential to have a significant impact upon fitness. Siblings will compete with one another in ways which they do not compete with non-siblings, requiring maternal care and attention rather than just foraging competitively. 

In a paper published in the journal Proceedings of the Royal Society B on 11 February 2026, Axelle Delaunay of the Institute of Evolutionary Science of Montpellier, and the Tsaobis Baboon Project in the Tsaobis Nature Park in Namibia, Vittoria Roatti, also of the Tsaobis Baboon Project, and of the Department of Anthropology at University College London, Rose Ellis and Punaete Kandjii, again of the Tsaobis Baboon Project, Alecia Carter, again of the Tsaobis Baboon Project and the Department of Anthropology at University College London, and of the Gobabeb Research Institute, Guy Cowlishaw of the Tsaobis Baboon Project, the Gobabeb Research Institute, and the Institute of Zoology, Marie Charpentier, also of the Institute of Evolutionary Science of Montpellier, and Élise Huchard, once again of the Institute of Evolutionary Science of Montpellier, the Tsaobis Baboon Project, and the Gobabeb Research Institute, present the results of a study into the role of jealousy in driving sibling competition in wild Chacma Baboons, Papio ursinus, a monotocous, social Primate.

Chacma Baboons live in matrilineal societies in which males disperse to new groups around puberty, while females remain within their birth groups, inheriting their mother's dominance rank. On average, females produce one young every two years, with growing Baboons are weened after about two years, but have a long developmental period and have long-lasting strong bonds to their mother, expressed through grooming relationships in which preference of grooming partner is an important signifier of relationship status.

In order to do this, they looked at instances in which young Baboons interrupted their mother when she was grooming a sibling. They did this to test three hypotheses, that young Baboons interrupted on such occasions because they were jealous, because they wished for attention from their mother themselves, or because they wanted to interact with their sibling. Theoretically, a jealous Baboon would interrupt even if it was not likely to gain any reward, a Baboon wanting attention from its mother would only interrupt if this was likely to result in it getting such attention, and a Baboon wishing to interact with a sibling would only do so if it was likely to gain such interaction. 

Theoretically, a Baboon which was jealous or wanted to play with a sibling would be more likely to approach its mother when she was grooming that sibling, while a Baboon simply wanting its mothers attention would be most likely to approach her when she was unoccupied. Furthermore, the jealousy hypothesis suggests that a Baboon would be more likely to interrupt its mother if she was grooming a sibling which tended to monopolise her attention, or otherwise appeared to be a favourite. This would fit with the patterns observed in Human children. 

It was also predicted that, in Baboons, jealousy would be more prevalent among same-sex siblings, and in particular between sisters, since younger sisters can come to outrank older sisters with maternal support. Since males leave the troop at puberty and do not rely on their mothers for social status, they were predicted to be less prone to jealousy. 

Furthermore, it was predicted that Baboons seeking maternal care would be more likely to interrupt when their mother was grooming a younger sibling, as these tend to be easier to displace, and that females may be more inclined to interrupt when their mother was grooming a male sibling, as mother-daughter social bonds are stronger than mother-son bonds.

If Baboons interrupt grooming because they want to play with a sibling, then males interrupting when other males were being groomed would be predicted to be the more frequent occurrence, as young males play with other young males more frequently than females play with females, or young Baboons play with members of the opposite sex. This would also lead to more interruptions when the Baboon being groomed was close in age to the Baboon interrupting. 

Dalauney et al. studied Chacma Baboons from two well habituated troops (L and J) in the Tsaobis Nature Park, which lies on the edge of the Namib Desert in Namibia, between August and December 2021. The Baboons were followed from dawn to dusk each day by trained observers who were able to identify all Baboons in the troops, including infants. Every family group which included at least a mother and two offspring was included in the study. This comprised eight families in each troop, with between two and five offspring, with a total of 28 female and 21 male young Baboons, ranging in age from six days to 8.9 years. This included adult females, but not adult and subadult males still living in the maternal group, due to the limited amount of interaction these males have with their mothers. 

Female Baboons were observed for five minute intervals when they were either grooming one of their offspring, or resting, and all interruptions were recorded, as well as whether this was be a sibling or non-sibling of the Baboon being groomed. Interruptions could be aggressive, such as attacking, chasing, biting, pushing, slaping, threatening, displacing, or supplanting; affiliative behaviours such as body contact, come-here faces, grunting, jumping on one groomer, lipsmacking, playing, presenting, or touching; tantrum behaviours such as gecks, complaint grunts, or other screams; maternal care solicitations, such as soliciting access to the nipple, soliciting grooming, suckling, or starting a triadic grooming session with the groomers; or simply approaching within a metre of a grooming pair. Under this analysis, a very broad range of behaviours were treated as 'interruptions', the object being to understand the motives of young Baboons in approaching their mothers. As such, focusing only on agonistic behaviours or effective disruption would only provide a partial picture of sibling interference, and might not pick up on some relationships, for example if younger siblings were afraid to behave aggressively towards older siblings being groomed by their mothers, but still found other ways to gain her attention. 

Having come up with a definition of 'interruptions', Dalauney et al. then looked at the outcome of these interruptions, grouping them into three basic categories; instances where the grooming continues, instances where the grooming stops, and instances in which the interrupter replaces one of the Baboons in the grooming relationship. In the final case, they recorded which Baboons were in the new grooming relationship (i.e. mother and interrupting youngster, or interrupting youngster and previously involved youngster). Finally, Dalauney et al. recorded every youngster within 10 m of their mother at the start of a five minute session. If the mother broke off from her original activity (grooming or resting) to engage in some other activity during the five minutes of the observation, that observation was abandoned. Each family group was monitored for no more than five minutes each hour. 

A juvenile male just approached and initiated body contact with his younger sister being groomed by their mother. This interference did not interrupt the ongoing grooming interaction, nor allow him to groom with his mother or his sibling. Axelle Delaunay in Dalauney et al. (2026).

Dalauney et al. found that young Baboons were significantly more likely to interrupt their mother when she was grooming a sibling than when she was resting, which predicted by the theories that the young Baboon was jealous or wanted the attention of its sibling, but not by the theory that the primary motivator was gaining the attention of the mother. This was unaffected by the presence of other siblings within 10 m (which was predicted to make interruptions less likely if a young Baboon was looking for a sibling to play with), nor was it affected by the sex of the youngsters, nor the social status of those involved. Baboons did become less likely to interrupt their mother grooming a sibling as they got older.

Younger Baboons were more likely to interrupt their mother when she was grooming a sibling, but this was apparently unaffected by the age-difference between them and the sibling being groomed. However, older siblings were twice as likely to interrupt their mother when she was grooming a younger sibling, and all Baboons were more likely to interrupt their mother when she was grooming a sibling of the same sex, with males more likely to interrupt when a brother was being groomed than females were to interrupt when a sister was being groomed. If one of the mother's offspring was perceived as a favourite, and received more grooming attention than its siblings, then those siblings were more likely to interrupt when it was being groomed. The age of this favourite did not appear to matter. This again supports the theory that interrupting Baboons were driven primarily by jealousy. 

Of 501 instances of Baboons interrupting their mother while she was grooming a sibling, 95 instances (19%) resulted in grooming being broken off (the predicted desired outcome of the jealousy model), while in 44 cases (9%) resulted in the interrupter entering into a grooming session with the mother (the predicted desired outcome of the maternal attention-seeking model), and only 12 (2%) resulted in the interrupter entering into a grooming session with the sibling (the predicted desired outcome of the sibling attention-seeking model). Entering into a grooming relationship with the mother or a sibling did not necessarily disrupt the original grooming relationship, as Baboons can form grooming triads. Data was not initially collected on interrupters entering into play relationships with the sibling being groomed (another possible outcome of the sibling attention-seeking model), but only 11 instances of this were observed, limiting support for this hypothesis. Thus, while most attempts at interrupting a mother grooming a sibling failed to disrupt that activity, they were significantly more likely to cause that grooming session to break off than to allow the interrupting Baboon to enter into a grooming relationship with one of the originally involved Baboons, supporting the hypothesis that the main reason for such interruptions was jealousy.

Interference are rarely successful, but more often disrupt the ongoing grooming than they grant access to maternal or sibling grooming. Proportion of successful interference as defined under the jealousy hypothesis (i.e. the interference effectively disrupts the ongoing mother–sibling grooming, in pink), the care-seeking hypothesis (i.e. the interferer gains access to maternal grooming, in orange), and the sibling-seeking hypothesis (i.e. the interferer gains access to sibling grooming, in yellow). Note that interferer do not need to disrupt the ongoing grooming to gain access to maternal or sibling grooming, as interference leading to triadic grooming interactions was also considered successful. The blue bar represents all the interferences that were not successful under any hypothesis, i.e. when the grooming kept going and the interferer did not get access to either of the groomers. Dalauney et al. (2026).

Dalauney et al.'s study lends to support to the idea that young Baboons interrupt their mothers when they are grooming siblings out of jealousy. They were more likely to interrupt their mothers when they were grooming siblings than when she was apparently available. They were also more likely to interrupt when the sibling being groomed was younger than them, of the same sex, or perceived as their mothers favourite. This interference appeared to be largely aimed at the mothers rather than their siblings. In Baboon societies, mothers are a more useful social connection than siblings, as they provide support to female offspring throughout their lives, and to male offspring for as long as they remain within their maternal group, whereas brothers will leave the group at some point, and sisters will shift the focus of their support to their own offspring when they start to have them.

Younger siblings were preferentially targeted over older siblings. This may be because younger Baboons tend to monopolise their mothers attention, or because they are less likely to respond aggressively to such interruptions. There is a lack of comparative studies of this behaviour in Humans, where only the jealousy of older siblings towards younger siblings has been explored, and then only in the context of age difference between siblings in modern Western societies.

What has been recorded in both modern Western societies and non-Human Primates is that behaviour predicted to be caused by jealousy is more commonly directed at younger siblings, and siblings of the same sex (which implies that in both cases offspring of different sexes are competing for slightly different maternal resources, and that siblings of the same sex are therefore a greater threat). In Baboons and Humans, young males engage in more rough-and-tumble play than young females, which might lead to a desire to play with siblings becoming a reason to disrupt interactions between those siblings and their mothers. Dalauney et al. believe that by looking at a wide range of interrupting actions and their outcomes, that their study has screened for this possibility

Dalauney et al. believe that the tendency of Baboons to interrupt when their mothers are grooming a sibling perceived as a favourite is important. This matches the finding in Humans that children who feel disfavoured by their parents report higher levels of conflict with both parents and siblings, often with lifelong consequences. In Humans, siblings are less likely to be jealous if they perceive that siblings receiving different treatment are doing so because they have different needs. Non-Human Primates are known to be able to track relationships between their close family and social partners, as well as those between third parties. Dalauney et al.'s findings suggest that Chacma Baboons are able to judge the strength of their maternal bond compared to that of their siblings, although the cognitive ability needed to do this and the perception of fairness in Baboons will need to be the subject of further studies. Negative responses to uneven food rewards have previously been recorded in several Primate species, as well as Domestic Dogs and Corvids. Whether Primates can assess maternal care in the same way is still unclear, but the ability to do so would clearly have implications for family dynamics.

One of the most important questions that arises from Dalauney et al.'s study is whether there is any benefit to a young Baboon in simply disrupting its mother grooming a sibling, and whether there is any more general advantage to jealousy. Interrupting activity was shown to be twice as likely to result in the mother abandoning grooming of a sibling as it was to result in the interrupter entering into a grooming session with the mother, and entering into such a grooming bout does not actually require the mother to abandon the other youngster, as Baboons can form grooming triads. Notably, the most common outcome was that nothing changed, i.e. the mother continued to groom the sibling she had been grooming when interrupted. This suggests that any benefits associated with jealousy may be complex and time-delayed, particularly if young Baboons are able to manage their emotional state sufficiently to refrain from an activity unlikely to pay off. Any adaptive benefits of jealous behaviour are likely to change over a lifetime, which should also alter their expression. There is less advantage to a Baboon monopolising its mothers time and attention as it becomes older and more independent, able to find its own resources and make its own social connections. Under these circumstances, sibling connections might become more important than maternal connections. In strictly evolutionary terms (i.e. the passing on of genes), it may be advantageous to an older juvenile Baboon to stifle jealous instincts in order to let a younger sibling have more time with its mother.

Ultimately, whether we are Human or Baboon, our emotions are a private matter, confined within our heads, which others can only judge by our actions. It is therefore possible that, when judging the emotions of another species, that we anthropomorphise their motivations, and provide emotional explanations for actions which have been determined by entirely different biological pathways. However, there is a growing body of evidence coming from a wide range of taxa, including Primates, Ungulates, and Corvids, that individuals will try to interfere with a close partners interactions with others, apparently in order to protect a valuable social relationship. Most studies have not attempted to evaluate the emotional underpinning of such actions, but these responses clearly correspond to what we would call jealousy in Humans. Dalauney et al. suggest that the role of emotions in managing social relationships in non-Human Animals has been underestimated, despite the fact that the primary function of emotions is to provide a way for individuals to act upon external stimuli. Jealousy is a social emotion, something which helps us to navigate complex social environments, and comparisons of Human and non-Human responses to similar social stimuli can potentially unlock ways to understand the emotional lives of Animals. 

See also...

Nasalis larvatus: Estimating the conservation status of the Proboscis Monkey on the Klias Peninsula, Borneo.

Almost half of all non-Human Primates are considered to be threatened by habitat loss due to Human activities, principally the clearing of forests for urban expansion, agriculture and agroforestry, or simply timber. Primates are thought to be particularly vulnerable to these pressures due to their long life-cycles and slow breeding rates, requiring access to a range of forest resources, which in turn makes it hard for them to adapt to changes to their environments, particularly those driven by Humans. Because of this, conservation efforts directed at Primates need reliable information on the distribution of Primates and the resources upon which they rely.

The forests of Southeast Asia are considered to be of international importance by conservations, with a number of biodiversity hotspots. These forests have come under considerable pressure in recent years, with huge areas cleared for agriculture, principally the cultivation of Oil Palms, Elaeis guineensis. Particularly threatened by this expansion are the forests of Borneo, an island with a high level of endemism (i.e. species not found anywhere else) where large areas of forest have been cleared to make way for Oil Palm plantations, and where, in addition to the direct loss of forests, many wildlife populations are additionally threatened by hunters making use of the road networks put in to support the Oil Palm industry.

Proboscis Monkeys, Nasalis larvatus, are large, sexually dimorphic Monkeys endemic to Borneo, which are considered to be Endangered under the terms of the International Union for the Conservation of Nature's Red List of Threatened Species. They get their common name from the prominent noses of the adults, these being more distinctive in the larger males than the smaller females. These Monkeys typically live in groups with a single male, plus several females and their young, although groups of young males are also found. The species is found in lowland forests close to water, such as riverine forests, mangroves and peat swamps, environments which are increasingly threatened by the expansion of Oil Palm cultivation, which is typically carried out on lowland floodplains. This expansion is known to have caused problems for Proboscis Monkeys, with their habitat increasingly being fragmented into smaller areas.

 

A male Proboscis Monkey, Nasalis larvatus, in Borneo. Mark Louis Benedict/Rainforest Rescue.

In 2004 a survey of the Klias Peninsula on the eastern tip of the Malaysian state of Sabah, found 569 individual Proboscis Monkeys living in groups, while a second survey carried out in 2005, which surveyed forests along the major rivers and tributaries of Sabah State by boat, found 818 Proboscis Monkeys on the Klias Peninsula, living in 75 groups. Both surveys found that the Klias Peninsula population was the largest surviving population in the state, and probably the only population large enough to have long-term survival prospects. This reliable presence of Proboscis Monkeys has turned the Klias Peninsula into somewhat of a tourist centre, with a number of companies offering opportunities to view the Monkeys.

In a paper published in the journal Raffles Bulletin of Zoology on 9 June 2021, Henry Bernard of the Unit for Primate Studies-Borneo at the Universiti Malaysia Sabah, Nicola Abram of Forever Sabah, Menaga Kulanthavelu and Felicity Oram, also of the Unit for Primate Studies-Borneo at the Universiti Malaysia Sabah, and Ikki Matsuda, again of the Unit for Primate Studies-Borneo at the Universiti Malaysia Sabah, and of the Academy of Emerging Sciences at Chubu University, the Wildlife Research Center of Kyoto University, and the Japan Monkey Centre, present the results of a previously umpublished survey of the Proboscis Monkeys of the Klias Peninsula, undertaken in 2014, combined with a comparison of this survey to the 2004 survey, undertaken with a view to understaning any changes in the population over a ten year period.

The Klias Peninsula has an area of about 1300 km², and is genrally flat, with a maximum elevation of about 50 m above sealevel. Historically, the peninsula was covered by complex mixture of Mangrove, Nipah Palm forest, freshwater swamp forest, and peat swamp forest, interspersed with open areas and extensive wet grasslands, but much of this has been cleared to make way for small scale Human settlements and farming, as well as larger Rubber and Oil Palm plantations. Bernard et al. carried out surveys by boat, along the Padas, Padas-Damit, Klias, and Bukau rivers, concentrating on areas where Proboscis Monkey populations had been detected by the 2004 and 2005 surveys. These included the Padang Teratak Bird Sanctuary, the Padas Damit Forest Reserve, the Menumbok Forest Reserve, the Binsulok Forest Reserve, the Klias Forest Reserve, the Kg. Hindian Forest Reserve, and the Nabahan Forest Reserve.

 

The Klias Peninsula region in western Sabah, in the northern part of Borneo (inset), Malaysia, and the research sampling sites in riverine, Mangrove, and mixed Mangrove-riverine forests along rivers in Padang Teratak Bird Sanctuary, Padas Damit Forest Reserve, Menumbok Forest Reserve, Binsulok Forest Reserve, Klias Forest Reserve, Kg. Hindian Forest Reserve, and Nabahan Forest Reserve, where the river surveys of the sleeping sites of Proboscis Monkeys were conducted. Bernard et al. (2021).

Proboscis Monkeys are almost always found close to water, favouring flooded forest environments, so boat surveys are generally the best way to survey them. These Primates return to a communal roost in a tree by a riverbank each evening, which makes surveying them relatively easy, particularly if this is done first thing in the morning, before they leave the communal roost, or late in the afternoon, after they have returned to it. Therefore, Bernard et al. carried out surveys of Proboscis Monkeys between 5.30 and 9.30 am and between 4.00 and 6.30 pm, between January and March 2014. All of the main rivers and tributaries in the study area were surveyed once only, to prevent double counting. Where waterways were close together they were surveyed on the same, or at least consecutive, days, for the same reason. A total of 106 km of waterways was surveyed, in sections ranging from 6.5 to 21.7 km. The locations of trees with Monkeys in them were recorded accurately with a GPS receiver, as were the number of Monkeys in each tree, and the type of group present (single male with females or all male group), and the type of forest the location was in (Mangrove, riverine, or mixed Mangrove-riverine). The extent of each habitat type was also recorded by length along the riverbanks, and the preference of the Monkeys for each habitat calculated from this.

Bernard et al. also carried out a number of vegetation surveys. There were carried out on 40 m circular plots, with 4-6 at each site, for a total of 34 plots. Within these plots all trees with a trunk-thickness greater than 10 cm at breast height were assessed, in order to work out the total area of all the tree stems within each plot, the largest tree within each plot, and the species richness at each plot.

To assess the amount of Human disturbance at each site, Bernard et al. used two measures; the distance from the centre of each site to the boundaries of the three closest agricultural sites, and the distance from the centre of each site to the boundaries of the three closest Human settlements.

Bernard et al. estimated the abundance of Proboscis Monkeys at each site by dividing the number of Monkeys by the area of the site, then used this measure to compare to the total area of all the tree stems within each plot, the species richness within the plot, and the size of the largest tree, as well as the distance to agricultural land and Human settlements.

Bernard et al. attempted to esitmate the loss of available habitat to the Proboscis Monkeys by calculating the potential range as being all the land 1 km inland of all the surveyed rivers, calculating the land cover throughout this area for both 2004 and 2014 using Landsat and Google Earth imagery, then calculating the change from suitable to unsuitable for Monkey habitation, based upon the parameters established by the ground surveys.

Finally, Bernard et al. calculated the amount of Monkey habitat currently within protected areas, using data from the Sabah Forestry Department, as well as the extent of the habitat outside these protected areas upon which titles have been granted for large scale plantations or other agribusiness enterprises (typically Oil Palm growth), what proportion is under Native Titile (reserved for the use of indigenous people), and what proportion is under, or available for County Lease (available for development for any purpose, and therefore again likely to be converted to Oil Palm planting), as well as land that was either no form of title, or for which the title was impossible to determine.

During 35 days of fieldwork on the Klias Peninsula, Bernard et al. carried out 42 surveys at seven study sites. They found 679 Proboscis Monkeys living in 75 groups; 44 groups comprising a males and a group of females plus their young, 16 groups of young males, and 15 groups whose composition could not be determined. The Monkeys were at their most abundant in the Padas Damit Forest Reserve in the central part of the peninsula, where there were 200 Monkeys living in 21 groups. Proboscis Monkeys were only found in Mangrove and riverine forests, giving them a total available riverbank habitat of 105 km (65 km of Mangrove forest, 35 km of riverine forest, and 5 km of mixed Mangrove and riverine forest). More Monkeys were found in Mangroves (412) than riverine forest (267), although once the greater availability of Mangroves was taken into account, this indicated a preference for riverine forests (where there were an average of 7.6 Monkeys per km) over Mangroves (where there were an average of 6.3 Monkeys per km).

Within these three forest types there was a significant variation in the vegetation, which also appeared to influence the abundance of Proboscis Monkeys. The species richness of the forests did not appear to be important to the Monkeys, but the total trunk basal area (a measure of tree maturity) was important, with more Monkeys being found where this was highest, possibly because mature trees are important for roosting sites. The closeness of Human habitation or agricultural land did not appear to be a problem for the Monkeys.

Between 2004 and 2014 the Klias Peninsula lost 11 520 m² of intact forest, most of it riverine forest (11 450 m²). In addition, 11 960 m² of degraded forest (forest which still existed as woodland but had lost much of its original biodiversity) and swampland were lost. During the same time the area of Oil Palm plantations within Proboscis Monkey habitats grew by 23 210 m², although 21 860 m² of this (94%) was later judged to be economically unprofitable due to flooding and swampy conditions.

Within the total potential range of the Proboscis Monkeys in 2014, 49% was covered by Mangrove forests, 11% by 'other forest types' (presumably riverine forest), and 18% by degraded areas and swamps, suggesting that 78% of the species total range was covered by suitable habitat and 18% by marginal habitat. The remaining parts of the range were covered by Oil Palm plantations (14%), community agriculture (7%) and aquaculture (1%), all unsuitable habitats for Monkeys.

Much of the remaining potential habitat is not protected, with only 20% of riverine forests and 59% of Mangroves having protected status (i.e. 52% of the remaining suitable environment). In addition 6% of degraded forests and swamplands are protected. This means that 80% of riverine forests, 41% of Mangroves, and 94% of degraded forests and swamplands are at risk of being lost.

Of the remaining forests, 14% (19% of the riverine forest and 13% of the Mangroves) was in Production Forest Reserves, 16 920 m² (all of it Mangroves) in Class V Mangrove Forest Reserves and 29 360 m² (11 820 m² of riverine forest and 17 540 m² of Mangroves) was in Class IV Amenity Forest Reserves, where some commercial exploitation is allowed.

About 27% of the remaining forests (including intact and degraded forests and swamps) is on land which has been granted for development. This toral includes 43% of remaining riverine forests, about 13% of Mangroves, and around 35% of degraded forests and swamps. Furthermore another 16-17% of each forest type is located on State Land, for which permits for use could potentially be issued.

 

Land use and land cover data for 2014/2015 within the 1-km buffer distance from surveyed rivers, overlaid with Proboscis Monkey sightings from the 2004/2005 and 2014 surveys, Protected Areas, and Production Forest Reserve boundaries. Bernard et al. (2021).

Bernard et al. discovered populations of Proboscis Monkeys at all of the surveys locations on the Klias Peninsula, with the largest population on the central part of the peninsula. This suggests that the area can be seen as a population stronghold for the species. The distribution of the Monkeys was similar to that observed in 2004 and 2005. The 2004 and 2005 surveys found 569 individuals in 65 groups, and 818 individuals in 75 groups, respectively, to which the 679 individuals in 75 groups found by Bernard et al. compares favourably. It is likely that the differences in Monkey numbers between the counts relate to the erratic nature of Monkey behaviour and the difficulties of surveying these primates in tropical wetland environments rather than actual fluctuations in the population, and, therefore, that the population remained fairly constant between 2004 and 2014). This would appear to correlate with the limited loss of environment suffered by the Monkeys between 2004 and 2014, during with time only 2% of riverine forests disappeared, and no Mangroves.

The Monkeys were not evenly distributed throughout their environment, apparently prefering riverine forests to Mangroves, and Mangrove forests to all other environments, including mixed riverine/Mangrove forests (although the avoidance of this later environment might be an artefact, as onlu 5 km of this environment was surveyed during the study). Studies in other areas have suggested Probiscis Monkeys prefer riverine forests to either Mangroves or mixed riverine/Mangrove forests, probably due to a higher plant diversity and greater variety of food in this habitat, although Mangroves are still clearly also an important habitat.

The presence of large trees appeared to be particularly important to these Monkeys, probably because of their role as roosting sites. Larger trees both provide a greater number and variety of nesting sites, but also provide a greater distance between these sites and the ground, making it harder for predators to reach the resting Monkeys undetected.

The study did not find any direct impact on Proboscis Monkey populations made by the proximity of Human settlements of agriculture, although this may have been due to the small size of the survey. The largest threat to wildlife populations on Borneo is currently considered to be the expansion of Oil Palm plantations, and, as with other Primate species, Proboscis Monkey's tend to avoid these environments, which are comprised of extensive monocultural stands of an unfamiliar fruit tree. Other than this however, Proboscis Monkeys seem to be relatively tolerant of the presence of Humans, and will even roost close to Human settlements if that is where suitably large trees are to be found. 

Little forest was lost on the Klias Peninsula between 2004 and 2014, but there is clearly the potential for much more to go, with the 28% of riverine forest currently designated for development being of particular concern. Grants of land made under such schemes in Sabah come with time limits; i.e. if the holder does not use the land within a certain period of time, then they lose the title, which can be granted to another user. These schemes currently make no provision for the retention of intact forest, clearly creating an incentive for developers to fell such forests to retain control of the land. As such Bernard et al. strongly recommend that the law be changed to allow landowners to leave areas of forest intact in order to protect the Proboscis Monkeys.

Also of concern are the large areas of forest designated as Production Forest Reserves, particularly the area within the Padas Damit Class IV Amenity Forest Reserve, which is the area with the greatest population of Proboscis Monkeys. These areas were originally intended to be areas of forest which were left largely intact, but where a range of leisure activities were permitted, however a follow up study in 2017-18 found that large areas under this designation had been converted to Oil Palm cultivation.

Proboscis Monkeys require forests along river margins to survive. As such the fragmentation of such environments not only lowers the amount of available habitat, but also removes their ability to move from one area to another, as their preferred environment is essentially linear. Thus protecting the species in future will require not just careful monitoring of their population, but careful management of the areas where they live, and in particular careful monitoring of land use changes likely to have an adverse effect.

Bernard et al. feel it would be particularly useful to grant full protection to Proboscis Monkeys living on government land, as this would have the issuing of land grants within areas of Monkey habitat, and allow the designation of protected areas to protect the Monkeys.

The Klias Peninsula is a popular tourist destination, and viewing Proboscis Monkeys is a popular activity with tourists. Thus good management of the Monkey population is likely to be of economic as well as conservational benefit, drawing tourists to Sabah, and generating income for local communities.

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Mico munduruku: A new species of Marmoset from the Amazon Basin.

Marmosets are small New World Monkeys, Platyrrhini, with claw-like nails and the incisor and canine teeth of the lower jaw modified for boring holes in Trees to obtain sap, a significant part of their diet. The group is well studied in the Atlantic Forests of Brazil, but also present in the forests of the Amazon Basin, where they are less well understood.

In a paper published in the journal PeerJ on 25 July 2019, Rodrigo Costa-Araújo of the Instituto Nacional de Pesquisas da Amazônia and the Departamento de Genética at the Universidade Federal do Amazonas, Fabiano de Melo of the Departamento de Engenharia Florestal at the Universidade Federal de Viçosa, and the Unidade Acadêmica Especial Ciências Biológicas at the Universidade Federal de Goiás, Gustavo Rodrigues Canale of the Universidade Federal de Mato Grosso, Sandra Hernández-Rangel, also of the Departamento de Genética at the Universidade Federal do Amazonas, Mariluce Rezende Messias of the Departamento de Biologia at the Universidade Federal de Rondônia, Rogério Vieira Rossi of the Departamento de Biologia e Zoologia at the Universidade Federal de Mato Grosso, Felipe Silva of the School of Environment and Life Sciences at the University of Salford, and the Instituto de Desenvolvimento Sustentável Mamirauá, Maria Nazareth Ferreira da Silva of the Coleção de Mamíferos at the Instituto Nacional de Pesquisas da Amazônia, Stephen Nash of the Department of Anatomical Sciences at Stony Brook University, Jean Boubli, also of the School of Environment and Life Sciences at University of Salford, and Izeni Pires Farias and Tomas Hrbek, again of the Departamento de Genética at the Universidade Federal do Amazonas, describe a new species of Marmoset from the Tapajós–Jamanxim interfluve (i.e. the area between the Tapajós and Jamanxim rivers) in the southwest of Pará State, Brazil.

The new species is placed in the genus Mico, and given the specific name munduruku, in honour of the Munduruku Amerindians of the Tapajós–Jamanxim interfluve. The species was first identified by its coat, which is distinctive and cannot easily be mistaken from that of any other previously described Marmoset, and later confirmed as a separate species by genetic analysis. Members of this species are white in colour with a a beige-yellowish spot on the elbow, and beige-yellowish saddle.

Mico munduruku, artists impression. Stephen Nash in Costa-Araújo et al. (2019).

Mico munduruku is found in lowland terra firme rainforest (i.e. rainforest which does not flood), from the left margin of the Jamanxim River, below the mouth of Novo River, possibly up to the right margin of the upper Tapajós River, below the mouth of Cururú River. The Tapajós–Jamanxim interfluve covers an area of about 120 000 km², slightly less than the area of New Mexico or England, although the area occupied by Mico munduruku is thought to only cover about 55 000 km². This region is one of the main fronts of forest destruction within the Arc of deforestation, a region infamously characterised by fast, intense and disordered conversion of forests to pastoral and agricultural land and human settlements, and has area has suffered extensive environmental damages due to illegal logging and agricultural expansion—this is happening even within federal conservation units and protected indigenous lands. There are also there are four hydroelectric plants in the process of implementation in this region. The population structure of Mico munduruku is to poorly understood to properly assess it's conservation status at this time, but Costa-Araújo et al. nevertheless express extreme concern about the future of the species given the immediate threats to its environment.

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Poaching in the Kakum Conservation Area of Ghana.

Tropical forests have come under unprecedented threat in recent decades, with wildlife populations threatened by both the felling of forests and hunting. To remedy this, many countries have introduced protected areas such as national parks within areas of tropical forests, within which the hunting or harvesting of wild animals and plants is strictly controlled or completely forbidden. Unfortunately, such schemes are typically imposed by central governments without any input from local communities that have lived in, and extracted resources from, these forests for centuries or more. This can mean that such communities suddenly find traditional sources of income and sustenance are suddenly forbidden, whereas any income from the new reserves typically goes into central government coffers, creating an sense of alienation, and a subsequent reluctance to cooperate with park schemes.

In a paper published in the Journal of Threatened Taxa on 26 February 2018, Edward Debrah Wiafe of the Department of Environmental and Natural Resources Management at the Presbyterian University College in Akropong-Akuapem, Ghana, presents the results of a 13 month study of poaching in the Kakum Conservation Area of southern Ghana.

The Kakum Conservation Area comprises the Kakum National Park, with an area of 210 square kilometres, and the Assin Attandanso Resource Reserve, covering 150 square kilometres. These were originally created during the colonial period (1931 and 1937 respectively), in order to protect the watershed that supplied the Cape Coast region, and to provide a source of timber. Establishing forest parks for the benefit of the timber industry might seem slightly contradictory, but in Britain, the colonial power in Ghana at the time, all natural forests vanished centuries ago, and with timber coming from managed and protected woodlands harvested on a rotational basis, with trees being left to grow for decades unmolested; unprotected areas tend to be rapidly converted to arable production, which produces a crop every year. The forests at Kakum were home to a number of local communities, which relied on the forests to provide them with resources through hunting and gathering, and occasionally some artisanal gold and clay mining, but little timber harvesting is thought to have occurred before the forest parks were created.

A raised walkway in the Kakum National Park; a popular attraction with tourists that provides a useful source of hard currency. Nicola Chiappi/Wikimedia Commons.

Today the area is protected by Wildlife Protection Rangers armed with G.P.S. units, compasses, grid maps and riffles, who enforce strict rules prohibiting anybody from hunting any animal or removing any plant from the reserve without express written permission, effectively making all hunting illegal. The reserve is home to a number of protected Mammals and Birds including African Elephant, Loxodonta africana, Maxwell’s Duiker, Philantomba maxwellii, Black Duiker, Cephalophus niger, Bongo, Tragelaphus eurycerus, Lowe’s Monkey, Cercopithecus lowei, Olive Colobus, Procolobus verus, Black and White Colobus, Colobus vellerosus, and Yellowbilled Turaco, Tauraco macrorhynchus. It is also home to 53 Human communities, who are now reliant on subsistance farming.

Wiafe collected data on arrests made by Wildlife Protection patrols between November 2012 and November 2013, including the number of arrests, the time of poaching equipment they were using and the numbers and types of animals they were caught with.

In November 2012 the patrols arrested two poachers, armed with snares and shotguns, and in possession of one Maxwell’s Duiker, 27 Rats and two live Pangolins. In December 2012 three poachers were arrested, armed with shotguns and in possession of ne Maxwell’s Duiker and two Pangolins.

A Maxwell’s Duiker, Philantomba maxwellii, considered to be Least Concern under the terms of the International Union for the Conservation of Nature's Red List of Threatened Species and hunted by poachers in the Kakum Conservation Area of Ghana. Paul Cools/iNaturalist/ICUN Red List.

In January 2013 the patrols arrested one poacher, armed with a shotgun, and in possession of two Maxwell's Duiker, one Lowe's Monkey, and one Spot-nosed Monkey. In February one poacher was arrested, in possession of snares and two Maxwell's Duiker, one Royal Antelope, one Tree Squirrel and a Potto. In march 2013 a single poacher was apprehended, armed with a shotgun and in possession of one Maxwell's Duiker and one Lowe's Monkey. In April 2013 no poachers were arrested.

A Lowe's Monkey, Cercopithecus lowei, in the Mole Game Reserve in Ghana. This species is again considered to be of Least concern under the terms of the ICUN's Red List, and is hunted in the Kakum Conservation Area of Ghana. Peter Strong/Wikimedia Commons.

In May 2013 four poachers were arrested, armed with shotguns and in possession of five Maxwell's Duiker, two Royal Antelope, two Lowe's Monkeys, and one Spot Nosed Monkey. In June no poachers were apprehended again, while in July 2013 three poachers were arrested, in possession of shotguns and having killed two Maxwell's Duiker, one Lowe's Monkey and one Elephant.

African Elephant, Loxodonta africana, in the Kakum National Park. The species is considered to be Vulnerable under the terms of the ICUN's Red List. Kakum National Park.

 

In August 2013 the patrols arrested one poacher, armed with a shotgun and in possession of one Royal Antelope, one Flying Squirrel, one Lowe's Monkey, one Olive Colobus, and one live Pangolin. No poachers were apprehended in September or October 2013, while in November 2013 another single poacher was arrested, this time armed with a shotgun and and in possession of one Maxwell's Duiker, two Lowe's Monkeys and two live Pangolins.

A Long-tailed Pangolin, Uromanis tetradactyla, in the Kakum National Park. One of three Pangolin species in the area, all of which are considered to be Vulnerable under the terms of the ICUN's Red List. Lars Peterson.

During the time of the study 69 animals were recovered by Wildlife Protection Rangers in the Kakum National Park, including 29 Rodents, 19 Antelope, 13 Primates, seven Pangolins, and an Elephant. Of these eight belonged to species considered to be Vulnerable under the terms of the ICUN's Red List of Threatened Species (the Pangolins and the Elephant) one belonged to a species considered to be Near Threatened (the Olive Colebus), while the remainder belonged to species considered to be of Least Concern. This pattern did not vary notably from that in areas where hunting is not illegal.

The favoured weapon of the Poachers was clearly the shotgun, which Wiafe notes is the weapon most conservationists would prefer to see used, as it is a discriminating weapon which allows hunters to only take the animals they want, unlike snares which are more random. This is not always the case in protected reserves, as the sound of shotguns can attract the attention of patrols, however in this instance the hunters reported preferring shotguns as they enable them to target animals in the tree canopy. However the Wildlife Rangers also reported sometimes finding fencing around paths in the reserves, directing animals to snares outside the bounds of the protected area.

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Macaca leucogenys, a new species of Macaque from Modog County in southeastern Tibet.

For a long time it was considered that there were two species of Macaques present in the forests of southeastern Tibet, Macaca assamensis assamensis (the Assam Macaque and Macaca mulatta (the Rhesus Macaque). However in recent years work by Indian researchers in Arunachal State (referred to in China as ‘Indian-controlled Tibet'), which shares continuous forests with southeastern Tibet, has led to the description a new species, Macaca munzala (the Arunchal Macaque) and the detection of a fourth species Macaca thibetana (the Tibetan Macaque), previously thought not to be present in the region. However not all primatologists in India have accepted these results, suggesting that instead the known species may be more variable than previously thought. In response to this, scientists on the Chinese side of the border began a series of observations of Macaques present there in 2013 and 2014, and set camera traps in the forests Modog County in southeastern Tibet. To their surprise this resulted in the discovery of what appears to be another species of Macaque in the region, distinguishable by its coat and genital anatomy.

In a paper published in the American Journal of Primatology on 25 March 2015, Cheng Li of the Imaging Biodiversity Expedition, Chao Zhao of the Institute of Eastern-Himalaya Biodiversity Research at Dali University and Peng-Fei Fan of the Faculty of Forestry at Southwest Forestry University formerly describe this new species as Macaca leucogenys, the White-cheeked Macaque.

Traditionally new species have been described by the assignation of type specimens in museums, against which other specimens can be compared to establish whether or not they belong to the same species. However the International Code of Zoological Nomenclature allows for the designation of photographs as types in the case of Primates, due to ethical concerns about killing wild specimens, and Li et al. take advantage of this provision to describe the new species from photographic data only, with the intention of obtaining museum specimens in the future.

Photo showing robust White-cheeked Macaque with brown to dark brown dorsal pelage and relative short tail. The end of the tail bends towards the ground in some individuals. White hair on cheeks and ears are visible. Li et al. (2015).

The White-cheeked Macaque has a relatively uniform brown colouration on its body, though the belly is lighter than the back. The hair on the muzzle is the same colour as the body, but the cheeks and ears are white. In older individuals these white hairs grow longer, and white hairs also appear on the snout. Juveniles lack white cheeks. The tail is hairless and tapering, being distinctly thicker at the base then the tip; in many individuals it has a distinct downwards kink close to it’s tip.

Family group of White-cheeked Macaques. Adult male in the right, adult female in the left and two small juveniles. Li et al. (2015).

White-cheeked Macaques were found in the forests of Madog County at altitudes of between 1395 m and 2700 m, an environment that ranges from tropical forests, through evergreen broadleaf forest and into mixed broadleaf-conifer forest, suggesting a degree of environmental flexibility. It may also be present in neighbouring counties of China or other Himalayan nations.

Map showing the rough distribution range of each species or subspecies of Macaca in southeast Tibet. Li et al. (2015).

At the moment all the forests of Modog County are protected by the Yarlung Zangbo Grand Canyon Nature Reserve, which prohibits destructive practices such as slash and burn agriculture. However local people in the area are known to kill Primates caught raiding crops, and also to occasionally actively hunt Macaques. More seriously the Chinese government is currently planning a series of hydroelectric dams in Modog County, including one which would completely flood the area where the White-cheeked Macaque. This threatens to directly destroy a large area of environment inhabited by the White-cheeked Macaque and other rare Primates, and in addition will bring a large number of workers into the area, which will lead to additional environmental disruption, by the building of roads, houses and other facilities for workers, as well as being likely to fuel a rise in the bushmeat trade in the area. Li et al. therefore call for more work to study and protect this important environment to be carried out as a matter of some urgency.

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