Joseph J. Erinjery

Drastic population decline and conservation prospects of roadside dark-bellied bonnet macaques (Macaca radiata radiata) of southern India

We carried out a survey on roadside dark-bellied bonnet macaques (Macaca radiata radiata) on the highways around the south Indian city of Mysore. The present survey was the fourth since 1989 on the same populations. We divided the habitats into intensive cultivation (IC), wet cultivation (WC), and scrub forests (SC). The number of groups has significantly reduced from 54 to 31 and the number of animals has declined from 1,207 to 697 from 1989 to 2009. This decline has been recorded only in the IC and WC areas, whereas the population in SC with places of Hindu worship has remained stable. Due to the loss of roadside Ficus trees over the years, the habitat of the monkeys has almost disappeared. Since bonnet macaque is not primarily a forest-dwelling species, the seemingly widespread primate may soon become ‘threatened’ if the non-forest populations continue to decline. Scrub forests in small hillocks housing Hindu temples remain the only prospective places for conservation of bonnet macaques.

Folivory as a Constraint on Social Behaviour of Langurs in South India

Folivory, being a dietary constraint, can affect the social time of colobines. In the present study, we compared food items and activity budgets of two closely related species of colobines inhabiting South India, i.e. the Hanuman langur (Semnopithecus hypoleucos) and Nilgiri langur (Semnopithecus johnii), to determine whether folivory had an impact on social time in these species. Our study established that Nilgiri langurs were more folivorous than Hanuman langurs. Nilgiri langurs spent much less time on social activities, but more time on resting, although the social organization of S. hypoleucos was similar to that of the Nilgiri langur. The enforced resting time for fermentation of leafy food items may have reduced the time available for social interactions, which in turn affected the social time in Nilgiri langurs. By comparing the data from previous studies on other Hanuman langur species, we found that S. hypoleucos spent a similar amount of time on social activities as Semnopithecus entellus. Hence, the social behaviour of S. entellus and S. hypoleucos is phylogenetically highly conservative.

Male Takeover and Infanticide in Nilgiri Langurs Semnopithecus johnii in the Western Ghats, India

Male takeover and infanticide are a widespread phenomenon among non-human primates, observed mostly in species with a relatively longer lactation in relation to gestation. In this study, we report for the first time an episode of male takeover and infanticide, and the rarely reported occurrence of an all-male band and female dispersal, in Nilgiri langurs, Semnopithecus johnii, in the Western Ghats, India. The new male was a member of an all-male band. After the takeover, the resident male and 3 juvenile males left the group and joined the all-male band. A female whose infant was killed was found missing after some days. There were significant changes in the patterns of social interactions among the resident group females soon after the male takeover, wherein the females spent less time on social interactions as compared to before and after the episode of takeover. The new male rarely interacted with the females soon after the takeover. We also observed that the resident group shifted its home range to a poorer quality habitat.

Deceased-infant carrying in nonhuman anthropoids: Insights from systematic analysis and case studies of bonnet macaques (Macaca radiata) and lion-tailed macaques (Macaca silenus).

Existing models of attachment do not explain how death of offspring affects maternal behavior. Previous descriptions of maternal responsiveness to dead offspring in nonhuman anthropoids have not expounded the wide variation of deceased-infant carrying (DIC) behavior. Through the current study, we attempt to (a) identify determinants of DIC through a systematic survey across anthropoids, (b) quantitatively assess behavioral changes of mother during DIC, and (c) infer death perception of conspecifics. Firstly, we performed phylogenetic regression using duration of DIC as the dependent variable. Secondly, we undertook case studies of DIC in the bonnet monkey and the lion-tailed monkey through behavioral sampling. Results of phylogenetic Generalized Linear Mixed Model (Nspecies = 18; Ncases = 48) revealed a strong homology (H2 = 0.86). We also obtained a high intraspecific variation in DIC and found DIC to be affected by mother’s age, context of death, habitat condition, and degree of arboreality. We found bonnet mothers to carry their deceased offspring for 3.56 ± 4.03 SD days (N = 7) with diminished feeding, enhanced passivity, and social isolation during DIC and progressive decline in protection/attentiveness of corpse and attachment. Following Anderson (2016)’s framework of death perception, we interpreted repeated sensory investigation of corpses by mothers as comprehending causality of death, inanimate handling of corpse and its defense as comprehension of non-functionality, and a progressive disinterest of mothers in them as perceiving irreversibility of death. Lastly, we integrated DIC with mother-infant attachment theories and proposed a conceptual model characterizing DIC with causal determinants.

Losing its ground: A case study of fast declining populations of a ‘least-concern’ species, the bonnet macaque (Macaca radiata)

The populations of many species that are widespread and commensal with humans have been drastically declining during the past few decades, but little attention has been paid to their conservation. Here, we report the status of the bonnet macaque, a species that is considered ‘least-concern’ for conservation. We show that the widely ranging rhesus macaque is expanding its range into the distributional range of the bonnet macaque, a species endemic only to southern India. Bonnet macaques have very low abundance in forests of all types indicating that it is not a typically forest dwelling species. The traditionally preferred habitats of bonnet macaques have been Hindu temples/ tourist spots but our data reveal that nearly 50% population of bonnet macaques has disappeared from such previously occupied spots. Another preferred habitat of bonnet macaques has been roadsides with abundant Ficus trees adjoining croplands. We found that between 2003 and 2015, the roadsides have drastically changed where vegetation has been replaced with barren lands and urbanization. Consequently, the populations of bonnet macaques have declined by more than 65% over the past 25 years, and by more than 50% between 2003 and 2015 alone. We, therefore, conclude that this ‘least-concern’ species is actually facing serious conservation challenges. We also identify a few places such as small hillocks with natural vegetation and a few temples/tourist spots which are likely to remain stable and thus can serve as ‘bonnet macaque conservation reserves’. Since the bonnet macaque shares many traits with several other commensal and ‘low-risk’ species, it can serve as a model for the development of long-term conservation strategies for most such species.

Behavioural Variability in Macaques and Langurs of the Western Ghats, India

Studies that compare differences in the behavioural variability across species and genera are rare among south Asian primates. Such studies are important for understanding within-group feeding competition in primates as interindividual difference in frequency of behaviour is a good indicator of feeding competition. We compared the variability in individual activities of lion-tailed macaques, bonnet macaques, Nilgiri langurs, and black-footed grey langurs. Both macaque species showed variability in their activities, with bonnet macaques showing higher variability than lion-tailed macaques. This indicated higher within-group competition in bonnet macaques than in lion-tailed macaques. Folivorous Nilgiri langurs and black-footed grey langurs did not show variability in any behaviour, indicating weak or negligible within-group competition. Except in the bonnet macaque, the interindividual differences in activities in the other species were potentially due to the differences between lactating and non-lactating females. We observed that langurs were less variable than macaques, indicating higher within-group competition in macaques than in langurs. We also observed a higher frequency of aggressive interactions during feeding among macaques than langurs, substantiating higher within-group competition in macaques than in langurs. We further discuss the different possibilities of within-group contest and scramble competition in these species.

Are interspecific associations of primates in the Western Ghats a matter of chance? A case study of the lion-tailed macaque

When animals or groups of animals in their wild habitats come close to each other within a defined distance, it is termed as an association. Observing two groups of the lion-tailed macaque at Nelliyampathy and Andiparai forests of the Western Ghats of India, we asked whether the lion-tailed macaque associations with the sympatric Nilgiri langur and bonnet macaque were by chance or had any biological significance. Employing ‘all occurrences’ sampling, we recorded an association if a group of another primate species came within 30 m of the focal group of the lion-tailed macaque. Date, time, associating species, activity of the study species and of the associating species, type of interaction, aggressor and the recipient, species displaced and duration of the association were recorded. We used the Waser gas model to calculate the expected frequency and duration of associations and compared them with the observed associations. The lion-tailed macaque spent less time in associations than expected. The lion-tailed macaque and the Nilgiri langur initiated associations less often, and remained in association for less time, than expected by chance. Whereas the expected and observed initiation of associations between the lion-tailed macaque and the Nilgiri langur in Nelliyampathy was significantly different (expected rate = 153; observed rate = 64), in Andiparai, it was not (expected rate = 55.5; observed rate = 61). The expected and observed association duration was significantly different in Nelliyampathy (expected duration = 54 min; observed duration = 15 min) and Andiparai (expected duration = 48 min; observed duration = 19 min). In contrast, we detected few differences between observed and expected association frequency for the lion-tailed macaque and the bonnet macaque. Aggressive interactions were common in areas where density of the Nilgiri langur groups was high. This is the first study on Asian primates using the ideal gas approach to show that primates do not form active associations with each other.

6th European Federation for Primatology Meeting, XXII Italian Association of Primatology Congress Rome, Italy, August 25-28, 2015: Abstracts

Classic ecological models of social groups suggest that increasing group size typically leads to a decrease in both individual predation risk and net food intake, with optimal group size being a compromise between these benefits and costs. Among rainforest primates, the main antipreda-tor benefits of sociality are thought to result from the dilution effect and collective detection of predators. However, recent research suggests that vegetation density in rainforest habitats limits the benefits of collective detection against ambush predators such as raptors, felids and snakes. Further, while larger groups are acknowledged to be more conspicuous to predators, it is widely assumed that this cost is unlikely to outweigh dilution benefits. Here we show in a simple model that per-individual rates of both encounters with predators and successful ambush attacks per encounter can increase with group size, under conditions likely to hold for many primate groups (when increases in group size lead to increases in group spread, conspicuousness and daily trav-el distance). Consequently, individual risk against ambush predators that employ a sit-and-wait strategy to search for prey, such as many snakes and some raptors, is lowest in small to medium-sized groups. In contrast, individuals in relatively large groups are favoured against ambush pred-ators like felids that employ a cruising strategy to search for prey, although even in this case in-creasing group size above some threshold increases individual risk. These results suggest that maximum group size among primates can be limited by increasing predation risk. Research fo-cused on primate predators is needed to determine the extent to which the model accurately re-flects their behaviour.Bushmeat hunting contributes to the decline of primate species across Africa; however, few studies have explored how such practises change over time in specific localities and how changes in land-use patterns and economic drivers may enhance threats to primates in Muslim dominated areas where, traditionally, primates are spared from such trade. The Haut Niger National Park (HNNP) is one of only two national parks in the Republic of Guinea. The park is one of the last remaining important formations of dry forest-savannah mosaics in West Africa and is a site of high conservation priority for ungulates and the western subspecies of chimpanzee. This study aimed to: (1) estimate the diversity and abundance of animal species sold for consumption across several markets in and around the HNNP, (2) analyse the evolution of the bushmeat trade since the mid-1990s, and (3) identify the players and drivers of the commercial bushmeat trade in the area. Local market assessments were conducted across four village markets and in Faranah, one of the closest urban areas abutting the HNNP. We successfully identified 5,807 wildlife carcasses of 46 species and 22 families on markets surveyed over a 7 month period spanning both the dry and wet seasons. In addition, semi-structured interviews with hunters, farmers and people involved in the bushmeat trade helped identify more recent drivers of the bushmeat trade in the HNNP. Our results indicated an increase in diversity of species targeted and the influence of crop-foraging and local microcredit systems in exacerbating the presence of primate species sold at bushmeat stalls in urban areas. Finally, whilst identifying key recommendations and gaps for future research, this study emphasises the growing risks facing primates as targets for bushmeat where people depend on agriculture and natural resource extraction for subsistence. This study complied with the International Primatological Society (IPS) Guidelines for the Use of Nonhuman Primates in Research.Comparative studies of primate grasping and manipulative behaviours in captivity have highlighted, among others, two human abilities that are generally considered unique compared with other primates: (1) the use of forceful precision and power squeeze grips involving the use of the thumb, and (2) a species-wide dominant use of one hand (usually the right hand), known as laterality. However, recent research has highlighted a diversity of precision and power grips in general among many non-human primates, and there is much debate around the potential for population-level or species-wide laterality in non-human primates. The majority of this research to date has been done on captive primates performing specific manipulative tasks, which may bias or confound these species comparisons. Comparatively little research has been done on hand use in wild primates, especially during natural, non-manipulative activities, including locomotion. Here, we investigate hand use during locomotor and non-locomotor behaviours in wild mountain gorillas ( Gorilla beringei beringei , Bwindi Impenetrable National Park, Uganda), wild chimpanzees ( Pan troglodytes verus , Tai National Park, Cote d’Ivoire) and chimpanzees kept under semi-natural conditions ( Pan troglodytes ssp., Chimfunshi Wildlife Trust, Zambia). Preliminary results propose that hand grips are similar between gorillas and chimpanzees during the manipulation of common object types. Bwindi gorillas show various hand use strategies during the processing of several plant foods. Chimfunshi chimpanzees also use forceful precision grips during daily manipulative tasks, suggesting that this is not a uniquely human ability.