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Individual and social behavioral responses to injury in wild toque macaques (Macaca Sinica)
Abstract
Toque macaques (Macaca sinica),inhabiting natural forest at Polonnaruwa, Sri Lanka, are frequently injured in fights with conspecifics. The behavior of known
individuals when they were injured was compared to that after they had recovered their health. Thus, injured animals rested
and alloand autogroomed more, but they foraged less and initiated fewer aggressive episodes. They spent most time being sedentary
in the safety of arboreal refuges and reduced acrobatic movements by locomoting more often terrestrially. Other group members
showed no special tolerance (or altruism) toward injury victims during the costly and highly competitive activity of foraging
for food. In fact, some injured animals received more aggression, or lost dominance rank, and thereby had their competitive
abilities further impaired. Care for the injured was manifest mostly by grooming and wound cleaning. All hair in the area
surrounding a wound, as well as dirt, scabs, and fly larvae, were removed, and saliva was applied by licking the wound (wounds
so treated healed with no obvious signs of infection). (1) Injured macaques sought and received significantly more grooming
(owing to wound care); (2) the amount so received increased with the severity of the injury; and (3) the initiative of other
group members often compensated for a victim’s inability to solicit care. Juvenile males were especially attentive to injured
adult males, suggesting that they were investing in a social bond with these adults, which might reciprocate altruism toward
their juvenile caregivers in the future. Injured juvenile females received most care from their mothers.
... It may also include a reduction in stress resulting from the traumatic event that caused the wound, through the release of the peptide hormone oxytocin (Beery & Kaufer, 2015;İşeri et al., 2010). Additionally, oxytocin and other hormones excreted as a result of communal wound licking may serve to strengthen social bonds among some group members (Chapman & Chapman, 1987;Clark et al., 2021;Dittus & Ratnayeke, 1989). ...
... Several species have been observed to engage in communal wound licking, with captive rodents and free-ranging primates constituting most or all of the cases reported (Spruijt et al., 1992). For example, instances of communal wound licking were observed for an individual spider monkey (Ateles geoffroyi; Chapman & Chapman, 1987), toque macaque (Macaca sinica; Dittus & Ratnayeke, 1989), and chimpanzee (Pan troglodytes; Clark et al., 2021). In all of these case reports, individuals were injured in fights with conspecifics. ...
The epidermis of wild mammals is occasionally lacerated or punctured, and wound care behaviours evolved to keep animals healthy in nature. Communal wound licking may promote healing of affected sites, relieve stress after a traumatic experience, and reinforce social bonds among individuals. Yet, there are few reported cases of communal wound licking in free-ranging mammals. We report observations of communal wound licking in a social ungulate—free-ranging bison (Bison bison). Two adult female bison presented with minor open puncture wounds after we chemically immobilized each of them with a dart fired from a rifle. The day after being darted, we observed three different adult bison lick the wounds of the two wounded bison. Both bison were <3 m of each other during this time and all of the observed wound licking occurred in <10 min. Our observation provides an additional example of communal wound licking in free-ranging mammals and extends it to a social ungulate. Benefits to bison of communal wound licking are perhaps largely social. However targeted research is needed to better understand both the frequency and cost and benefits of communal wound licking.
... First, we use receiving a bloodied bite wound during agonistic interactions, as such injuries are well-established acute stressors necessitating energetic mobilization (Barton, 1985). Second, we include the injury or sudden death of a group member, since these events alter social networks of individuals within groups, leading to social consequences in primates such as increased vulnerability to future agonisms or intragroup encounters (Campbell et al., 2016;Dittus and Ratnayeke, 1989;Gonçalves and Carvalho, 2019). Third, we assess whether acute stress associated with parturition is reliably detectable in FCMs. ...
Analysis of glucocorticoid profiles serves as a valuable, multi-faceted tool for insight into the behavior and physiology of wild populations. Recently, the measurement of fecal glucocorticoid metabolites (FCMs) has exploded in popularity due to its compatibility with noninvasive techniques and remote environments A critical first step is to perform a biological validation to ensure that the assay accurately reflect changes in FCM levels. We use an enzyme immunoassay (EIA) to perform a biological validation on samples collected from two males and six females in a wild population of Colobus vellerosus in response to three naturally occurring potential stressors. We also describe the FCM response pattern in the week following parturition in three females and examine the influence of sex, reproductive state, and time of day on the concentrations of baseline samples collected daily from 13 adult individuals over a period of four months. We validated the assay: FCM levels increase in response to natural stressors with a two-day lag. In the two days surrounding parturition, FMC levels increased. Baseline concentrations were affected by collection time and female reproductive state, with lactating females having lower concentrations than pregnant or cycling females. Thus, we successfully carried out the first validation and characterization of FCMs in a wild African colobine. This will serve as an essential foundation for future studies of C. vellerosus and similar wild primates whose objective is to investigate the role glucocorticoids play in responses to social and ecological challenges.
... Indeed, one female received two near-fatal early-life injuries, exhibited permanent locomotor impairments, and did not mature until 88.4 months-the oldest age at maturation observed in this population by over one year. Repairing such wounds likely shunts resources away from growth and reproduction, and these deficits could be exacerbated if associated locomotor difficulties hamper foraging or alter dominance trajectories (Dittus and Ratnayeke 1989). ...
Female reproductive maturation is a critical life-history milestone, initiating an individual's reproductive career. Studies in social mammals have often focused on how variables related to nutrition influence maturation age in females. However, parallel investigations have identified conspicuous male-mediated effects in which female maturation is sensitive to the presence and relatedness of males. Here, we evaluated whether the more "classic" socioecological variables (i.e., maternal rank, group size) predict maturation age in wild geladas-a primate species with known male-mediated effects on maturation and a grassy diet that is not expected to generate intense female competition. Females delayed maturation in the presence of their fathers and quickly matured when unrelated, dominant males arrived. Controlling for these male effects, however, higher-ranking daughters matured at earlier ages than lower-ranking daughters, suggesting an effect of within-group contest competition. However, contrary to predictions related to within-group scramble competition, females matured earliest in larger groups. We attribute this result to either: 1) a shift to "faster" development in response to the high infant mortality risk posed by larger groups; or 2) accelerated maturation triggered by brief, unobserved male visits. While earlier ages at maturation were indeed associated with earlier ages at first birth, these benefits were occasionally offset by male takeovers, which can delay successful reproduction via spontaneous abortion. In sum, rank-related effects on reproduction can still occur even when socioecological theory would predict otherwise, and males (and the risks they pose) may prompt female maturation even outside of successful takeovers.
Ant rescue behaviour belongs to the most interesting subcategories of prosocial and altruistic behaviour encountered in the animal world. Several studies suggested that ants are able to identify what exactly restrains the movements of another individual and to direct their rescue behaviour precisely to that object. To shed more light on the question how precise is the identifi-cation of the source of restraint of another ant, we investigated rescue behaviour of workers of the red wood ant Formica polyctena using a new version of an artificial snare bioassay in which a nestmate victim was bearing on its body two wire loops, one placed on the petiole and acting as a snare, and an additional one on the leg. The tested ants did not direct preferentially their rescue behaviour to the snare. Moreover, the overall strategy adopted by the most active rescuers was not limited to precisely targeted rescue attempts directed to the snare, but consisted of attempts to find a solution to the victim’s problem through frequent trial-and-error switching between various subcategories of rescue behaviour. These findings highlight the importance of precise identifica-tion of cognitive processes and overall behavioural strategies for better understanding of causal factors underlying animal helping behaviour.
Humans and animals exhibit various forms of prosocial helping behaviour towards
others in need1–3. Although previous research has investigated how individuals may
perceive others’ states4,5, the neural mechanisms of how they respond to others’ needs and goals with helping behaviour remain largely unknown. Here we show that mice engage in a form of helping behaviour towards other individuals experiencing physical pain and injury—they exhibit allolicking (social licking) behaviour specifically towards the injury site, which aids the recipients in coping with pain. Using microendoscopic imaging, we found that single-neuron and ensemble activity in the anterior cingulate cortex (ACC) encodes others’ state of pain and that this representation is different from that of general stress in others. Furthermore, functional manipulations demonstrate a causal role of the ACC in bidirectionally controlling targeted allolicking. Notably, this behaviour is represented in a population code in the ACC that differs from that of general allogrooming, a distinct type of prosocial behaviour elicited by others’ emotional stress. These findings advance our understanding of the neural coding and regulation of helping behaviour.
Weaning age in primates has been challenging to measure and new methods, involving molecular biomarkers in feces, tissue, or teeth have contributed to a solution. Here, we used a direct approach by briefly anesthetizing 442 female toque macaques ( Macaca sinica ) of Sri Lanka (over a 17‐year period) and manually testing their mammary tissue for the presence or absence of milk. Milk tests were related to known offspring ages and maternal care behaviors and indicated that older infants suckled milk well past the weaning age of 7 months that is often reported for food‐provisioned primates. Mothers strongly rejected their infants' nursing attempts in two phases, the first at 7 months as an honest signal “giving notice” promoting a shift to greater independence from milk to solid food, and when “shutting down” at final weaning after 12–18 months. The shift to supplementary lactation coincided also with the cessation of mothers carrying their infants and a resumption of cycling. All infants up to 7.2 months suckled milk, 91% of them did up to 18 months, this continued for 42% of infants beyond 18 months, and normally none received milk after 22 months. Lactation extended into 2.2% of cycling and 10.7% of pregnant females (up to 50% of gestation). The interbirth interval was prolonged by factors predicted to draw on female metabolic energy reserves and included the duration of lactation, growth among primiparas, and dietary limitations. The last also increased menarche. Females offset the metabolic costs of lactation with increased foraging and catabolism, but infants died when lactation costs seemingly compromised maternal condition. The prolonged lactation and slowed reproduction are considered adaptations to promote infant survival and growth in an environment where the natural food supply limits population growth and competition for food and water impacts the mortality of the youngest the most.
Congenital malformations, conditions, injuries, and illness can lead to long‐term physical impairment and disability in nonhuman primates. How individual primates change their behaviors flexibly to compensate for their disabilities can inform our understanding of their resilience and ability to adjust to environmental change. Here, we synthesize the literature on nonhuman primates and disability, addressing the questions: how does disability influence behavior in primates? What insights can we take from the literature to better understand and predict the capacity of primates to modify their behaviors in the face of human‐induced environmental change? We conducted a systematic review of the literature on spontaneous physical impairment and disability in captive, free‐ranging, and wild primates. We surveyed 2807 articles on Web of Science and Scopus and identified 114 studies that fit our predetermined inclusion criteria. Behavioral plasticity, maternal and conspecific care, and the potential for innovation of novel behaviors allow many primates with disabilities to compensate when faced with challenges that are outside the scope of usual circumstances. We also found that 60% of the publications connected primate physical impairment and disability to human activities, suggesting an entangled relationship among humans, the environment, and primate disability. Disability and physical impairments provide an opportunity to examine how primates modify their behavior when presented with challenging conditions, and their potential resilience to a changing environment.
While classified as endemic and endangered, the Toque Macaque (Macaca sinica) is also considered a nuisance species in certain habitats in Sri Lanka due to its increased interactions with humans and crop raiding. This study analyzed the activity budget and home range utilization of two M. sinica troops inhabiting two contrasting landscapes to shed light on the species' rather poorly understood behavioral responses under environments of differing levels of anthropogenic pressure. We observed two macaque troops; first in a landscape with lower anthropogenic pressure (LAP) in Yagirala, and second in an area of moderate anthropogenic pressure (MAP) in Korathota, Sri Lanka. We followed the troops for ten months and observed their behaviors using focal animal sampling. Both troops spent most of their time on foraging and locomotion. However, the Korathota (MAP) troop spent more time on vigilance behaviors than the Yagirala (LAP) troop, which spent more time on amicable behaviors. This suggests that time allocation to amicable behaviors by Toque Macaques is higher in areas with lower anthropogenic pressure. The home range size was significantly larger in Yagirala (LAP) troop. We further found a significant difference in average home range size across seasons in both troops (p=0.001) with larger home ranges in the dry season: 2.81ha in the wet season vs 3.98 ha in the dry season for MAP troop and 5.1ha in the wet season vs 8.66ha in the dry season for LAP troop. Findings suggest that the resource availability and the level of anthropogenic pressure influence the activity budget and home range size of Toque Macaques. The outcomes of this study may be instrumental in developing future management strategies for Toques Macaques in anthropogenic settings and reducing human-macaque conflict. Practical management and conservation efforts should reduce the availability of anthropogenic food sources to macaques while increasing the size of natural forest patches.
Characterizing non-human primate social complexity and its cognitive bases has proved challenging. Using principal component analyses, we show that primate social, ecological and reproductive behaviours condense into two components: socioecological complexity (including most social and ecological variables) and reproductive cooperation (comprising mainly a suite of behaviours associated with pairbonded monogamy). We contextualize these results using a meta-analysis of 44 published analyses of primate brain evolution. These studies yield two main consistent results: cognition, sociality and cooperative behaviours are associated with absolute brain volume, neocortex size and neocortex ratio, whereas diet composition and life history are consistently associated with relative brain size. We use a path analysis to evaluate the causal relationships among these variables, demonstrating that social group size is predicted by the neocortex, whereas ecological traits are predicted by the volume of brain structures other than the neocortex. That a range of social and technical behaviours covary, and are correlated with social group size and brain size, suggests that primate cognition has evolved along a continuum resulting in an increasingly flexible, domain-general capacity to solve a range of socioecological challenges culminating in a capacity for, and reliance on, innovation and social information use in the great apes and humans.
This article is part of the theme issue ‘Cognition, communication and social bonds in primates’.
Semi-evergreen forests cover the dry zone plains of Sri Lanka and constitute four-fifths of the island's vegetation. In a sample area of 3 km2, in the Polonnaruwa Sanctuary, 63 tree species were found; 46 were characteristic of other dry zone forests, and 17 occurred only under special edaphic and biotic conditions. As in other dry zone forests, Drypetes sepiara (Euphorbiaceae) prevailed with a relative density of 21.3 percent. The Shannon index of diversity was 4.23 bits per individual, of which 79.4 percent was attributable to evenness; most species had few individuals. Dominance was shared between species typical of the subcanopy and canopy. Measures of diversity and of dominance between species placed the semi-evergreen community in Polonnaruwa as a type intermediate between tropical rainforest and deciduous monsoon forest. Measures of diameters (DBH) and estimates of the height of trees indicated that all species with typically very large trees had few individuals that were distributed more or less evenly through all the size classes. Typically smaller species had large numerical representation. These facts are discussed in light of dominance relationships and regenerative patterns in the community, and are related to possible evolutionary trends. The distribution of most species was clumped, but that of certain rare species was random. Clumping at 2,500 m2 plot size usually meant clumping at smaller-sized plots. Clumping on a large scale reflected local differences in species dominance. Five shrub associations were distinguished by density and constitute dominant and co-dominant species. Differences were related to the amount of light penetrating through the tree canopy and to edaphic factors. Glycosmis pentaphylla (Rutaceae) was the dominant shrub species in the climax association which flourished under a fairly closed tree canopy and lacked an herbaceous layer.
1. Two independent groups of toque macaques (Macaca sinica) fused into one larger cohesive group. The groups were part of a population of 18 to 22 groups that inhabit natural forest at Polonnaruwa, Sri Lanka, and that had been observed more or less continuously from 1968 to 1985. 2. The group fusion generally supports WRANGHAM'S (1980) model of the evolution of group living and female residence patterns in