Groups Of Lemurs Research Articles

Diverse Circular DNA Viral Communities in Blood, Oral, and Fecal Samples of Captive Lemurs.

Few studies have addressed viral diversity in lemurs despite their unique evolutionary history on the island of Madagascar and high risk of extinction. Further, while a large number of studies on animal viromes focus on fecal samples, understanding viral diversity across multiple sample types and seasons can reveal complex viral community structures within and across species. Groups of captive lemurs at the Duke Lemur Center (Durham, NC, USA), a conservation and research center, provide an opportunity to build foundational knowledge on lemur-associated viromes. We sampled individuals from seven lemur species, i.e., collared lemur (Eulemur collaris), crowned lemur (Eulemur coronatus), blue-eyed black lemur (Eulemur flavifrons), ring-tailed lemur (Lemur catta), Coquerel's sifaka (Propithecus coquereli), black-and-white ruffed lemur (Varecia variegata variegata), and red ruffed lemur (Varecia rubra), across two lemur families (Lemuridae, Indriidae). Fecal, blood, and saliva samples were collected from Coquerel's sifaka and black-and-white ruffed lemur individuals across two sampling seasons to diversify virome biogeography and temporal sampling. Using viral metagenomic workflows, the complete genomes of anelloviruses (n = 4), cressdnaviruses (n = 47), caudoviruses (n = 15), inoviruses (n = 34), and microviruses (n = 537) were determined from lemur blood, feces, and saliva. Many virus genomes, especially bacteriophages, identified in this study were present across multiple lemur species. Overall, the work presented here uses a viral metagenomics approach to investigate viral communities inhabiting the blood, oral cavity, and feces of healthy captive lemurs.

Social Network Analysis as a Tool in the Care and Wellbeing of Zoo Animals: A Case Study of a Family Group of Black Lemurs (Eulemur macaco).

Social network analysis (SNA) is an increasingly utilised technique in the literature examining the social structures and organisation of animals and understanding the bonds between groups and individuals. Using a case study as an illustration, the applications of SNA are explored, including the identification of dominance hierarchies and detection of sources of social pressure, with a particular focus on the applications of SNA to holistic assessments of animal welfare alongside other methods. Based on the examination of social dynamics in a family group of four black lemurs (Eulemur macaco), a primate whose social organisation is characterised by patterns of female dominance, it is demonstrated that SNA can be used to examine the affiliative and agonistic interactions between individuals living in human care. SNA showed species-typical forms of female dominance that were largely directed towards the two males, characterised by the initiation of aggressive interactions and male submission. More intricate relationships and consistent social roles across networks were revealed through the examination of SNA. It is concluded that SNA has wide-ranging benefits in the assessment of effects of environmental changes, such as informing social management decisions, developing enrichment and intervention programs, and guiding overall improvements to the housing and care of individual animals. SNA, as part of an animal welfare toolbox, could, therefore, be a pivotal technique for modern animal welfare assessment that considers individual animals and their social lives. By sharing a case study of the technique in use, it is hoped that animal collections may adopt similar modern and evidence-based assessment methods.

Assessing the drivers of gut microbiome composition in wild redfronted lemurs via longitudinal metacommunity analysis

The gut microbiome influences host’s immunity, development, and metabolism and participates in the gut–brain axis, thus impacting the health of the host. It is a dynamic community varying between individuals and within individuals at different time points. Hence, determining the factors causing this variability may elucidate their impact on host’s health. However, understanding the drivers of variation has proven difficult particularly as multiple interactions occur simultaneously in the gut microbiome. We investigated the factors shaping the gut microbiome by applying the metacommunity concept where the gut microbiome is considered as a microbial community shaped by the interactions within the community, with the host and microbial communities outside the host, this through a longitudinal study in a wild primate. Focal behavioral data were collected for 1 year in four groups of redfronted lemurs to determine individual social and feeding behaviors. In addition, regular fecal samples were collected to assess bacteria, protozoa, and helminths through marker gene analysis and to measure fecal glucocorticoid metabolite (fGCM) concentrations to investigate the impact of physiological stress on the gut microbiome. Higher consumption of leaves and elevated fGCM concentrations correlated with higher alpha diversity, which also differed among groups. The major drivers of variation in beta diversity were group membership, precipitation and fGCM concentrations. We found positive and negative associations between bacterial genera and almost all studied factors. Correlations between bacterial indicator networks and social networks indicate transmission of bacteria between interacting individuals. We detected that processes occurring inside the gut environment are shaping the gut microbiome. Host associated factors such as, HPA axis, dietary changes, and fluctuations in water availability had a greater impact than interactions within the microbial community. The interplay with microbial communities outside the host also shape the gut microbiome through the exchange of bacteria through social relationships between individuals and the acquisition of microorganisms from environmental water sources.

Characterizing group and individual engagement in intergroup encounters between small groups of ring-tailed lemurs (Lemur catta) on St. Catherines Island, USA.

Primate species exhibit considerable variation in behavior and outcomes during intergroup encounters (IGEs). Social group characteristics, like group size, and individual traits, such as sex, rank, and reproductive status, within those groups can influence both IGE engagement and outcomes. To better understand the impact of group heterogeneity on IGEs, we must examine individual strategies to elucidate individual costs and benefits of engaging in these interactions. Here, we present a descriptive study of the IGEs between two small social groups of ring-tailed lemurs (Lemur catta) on St. Catherines Island, GA, USA. We distinguish between dyadic and multiple-individual interactions between groups to compare collective and individual agonistic engagement. All encounters occurred when the East Road group (N = 7 individuals) traveled from the center of their home range to the boundary with Windmill group's (N = 5 individuals) home range, indicating that East Road might have been actively testing this boundary for access to food resources, sleeping trees, and mating opportunities. We also found notable individual variation in participation during IGEs. The daughters of the highest-ranking females were the most-engaged in dyadic intergroup and intragroup aggression, had high "win" rates during intergroup dyadic encounters, and engaged in intergroup multiple-individual interactions at high levels. These findings indicate that they might value their home range more as "potential alphas" compared to other group members. Dominant females were the most engaged in multiple-individual interactions, suggesting that they contribute heavily to collective action that might result in a gain or loss of access to resources. Finally, these two small groups might be equally matched despite the two-individual group size disparity due to individual free-riding strategies. Future research should focus on individual strategies during IGEs to characterize the complex decisions and trade-offs that influence participation.

Coping with habitat disturbance: camera-traps reveal cathemerality of Prolemur simus in the community-managed area of Tsaratanana, eastern Madagascar

Abstract This study provides new findings on the flexible activity of Prolemur simus in an anthropogenically modified habitat in the rural commune of Tsaratanana, eastern Madagascar. Based on camera-trap data, we compared the temporal distribution of activity of one group of lemurs between the forest edge and the forest core. We also investigated the possible influence of nocturnal luminosity on the activity cycle. The analysis was conducted using Kernel Density estimates and the R package OVERLAP. The distribution across the 24-h cycle confirmed that Prolemur simus is cathemeral in the wild. The lemurs displayed three peaks of activity: one during the night and two coinciding with morning and evening twilights. The highest proportions of nocturnal activity occurred at the forest edge and at low moon luminosity suggesting a possible anti-predator and/or human-avoidance strategy. The flexible activity of Prolemur simus may contribute to the tolerance of this Critically Endangered species to anthropogenic disturbance.

Niche-separation and conservation biogeography of Madagascar’s fork-marked lemurs (Cheirogaleidae: Phaner): Evidence of a new cryptic species?

Ecological niche modeling can provide insights into a species’ demography, ecology and biogeography, and the environmental factors that determine them. Exploration of ecological niche models and niche-divergence among closely-related and cryptic organisms can also be useful for species delineation and discrimination, and such information can inform and facilitate conservation of their populations. In this study, I used an ecological niche modeling approach to investigate the conservation biogeography of the fork-marked lemurs (genus Phaner), a group of cryptic, nocturnal primates that are endemic to Madagascar. I constructed all ecological niche models in MaxEnt, using a range of climatic and habitat-related variables. I examined interspecific niche-separation within the Phaner genus, and among two sub-populations of P. electromontis, a species which has previously been hypothesized to represent two distinct, cryptic taxa. All ecological niche models performed well and with high accuracy, and whilst the percentage contribution of each environmental variable differed between species, the results suggested that climate may be the primary determinant of Phaner distribution. Further, all four Phaner species occupied distinct ecological niches, a result that was also mirrored in the two P. electromontis sub-populations. This suggests that one of the two sub-populations may indeed be a distinct, as-yet undescribed species, but further genetic and ecological research is needed to substantiate this result. Finally, the ecological niche models revealed that only 23.0% of the suitable land area for Phaner occurrence within Madagascar is forested, limiting the geographic distribution of these lemurs. Whilst much of this suitable habitat is thankfully protected, deforestation continues throughout Madagascar, and this under-studied group of lemurs requires further research attention and continued conservation efforts.

Ring-tailed lemurs (Lemur catta) use olfaction to locate distant fruit.

As many primates live in forests where visibility is limited, the ability to detect the aroma of distant fruit and navigate odor plumes would be highly adaptive. Our study is the first to investigate this ability with strepsirrhine primates. We tested the ability of a group of ring-tailed lemurs to detect hidden fruit from afar using scent alone. We hid containers in the underbrush of a semi-natural forest, some baited with real cantaloupe and some with sham cantaloupe, 4-17 m from a path routinely used by the lemurs. Crucially, the containers were not visible from the path. Therefore, the lemurs had to use olfactory cues, but did not have to prioritize them to locate the bait. The lemurs found the real cantaloupe on days that the wind blew the scent of the fruit toward the trail. They did not find the sham cantaloupe. Upon detecting the odor of the bait, the lemurs sniffed the air at one or more locations as they moved toward the bait, a process of navigation known as klinotaxis. The traditional belief is that primates are unable to track odor plumes. The untrained lemurs in this study were able to detect the odor of the cantaloupe among the complex odors of the forest and navigate the odor plume to the fruit. The results indicate that olfaction may be used to respond to cues from distant sources. The ability to track odor plumes may be a critical foraging skill for strepsirrhines.

Comparison of the Glucocorticoid Concentrations between Three Species of Lemuridae Kept in a Temporary Housing Facility.

Simple SummaryLemurs kept in captivity are constantly influenced by a number of factors that affect their welfare. All lemur species are classified as endangered species according to the International Union for Conservation of Nature (IUCN) Red List and their population in the wild is decreasing. It is therefore useful to improve the methods for assessing the level of stress in individual lemurs in captivity. In this study, we compared the changes in glucocorticoid concentrations in three species of Lemuridae in response to various types of potential stressors during their stay in a temporary housing facility. The glucocorticoid levels were specifically monitored for ring-tailed lemurs (Lemur catta), white-headed lemurs (Eulemur albifrons) and collared brown lemurs (Eulemur collaris).We compared the glucocorticoid concentrations in response to various types of potential stressors present during standard operation of a temporary housing facility between three species, namely, ring-tailed lemurs, collared brown lemurs and white-headed lemurs. The levels of faecal glucocorticoid metabolites (FGMs) were measured non-invasively on a daily basis during a 30-day period. A total of 510 faecal samples were collected. Concentrations of immunoreactive glucocorticoid hormone metabolites were measured in the obtained extracts by using an enzyme immunoassay. The polyclonal antibodies used in this assay were directed against the metabolite 11-oxo-etiocholanolone I. We found all three monitored lemur species to respond to specific potentially stressful situations by increasing (p < 0.05) the FGM levels within one to two days after the event. Although housed in the same room, differences in response to potentially stressful situations were found in white-headed lemurs compared to ring-tailed lemurs. Increased mean levels of the FGMs were found more frequently in white-headed lemurs than in ring-tailed lemurs. The results suggest that this species may be more sensitive to changes in its surroundings. In general, the levels of the FGMs showed a similar pattern during 30 days of monitoring suggesting that all groups of lemurs responded in a similar manner to the same events. However, we recorded the differences in the absolute values of glucocorticoid concentrations between the monitored species likely due to the differences in sex ratios in the groups and presence of lactating females in the ring-tailed lemurs.

Water Availability Impacts Habitat Use by Red-Fronted Lemurs (Eulemur rufifrons): An Experimental and Observational Study

With the predicted increase in extreme weather events as a result of global climate change, animals living in dry or seasonally dry habitats are likely to experience dramatic fluctuations in water availability from season to season and year to year. Understanding how animals respond to short-term changes in water availability is paramount for future conservation and management of water-dependent wild populations. We investigated how short-term changes to the availability of water influenced habitat use of four groups of red-fronted lemurs (Eulemur rufifrons) in a dry deciduous forest in western Madagascar using detailed spatial data collected from GPS collars over 15 weeks. We experimentally manipulated water availability in the habitat and compared ranging patterns of the lemurs during the experiments to those before and after the experiments. Lemur groups shifted the intensity of their habitat use relative to changes in natural and experimental water availability. Specifically, lemurs were more likely to spend time in areas near experimental water sources during the experiment than in the same areas without water. Lemurs were less likely to spend time near previous habitual water sources when experimental water sources were available. We observed shifts in ranging intensity in response to natural changes to water availability when waterholes disappeared across the dry season. Our findings support the importance of water for shaping wild animal ranging patterns. We propose that water should be a primary consideration in future studies of habitat use, especially given the potential for climate change and human land use to further alter water availability for wild animals.

Captive ring-tailed lemur breeding in semi-free ranging conditions and genetic parentage analysis.

The ring-tailed lemur (Lemur catta), one of the most iconic and widely recognized primates in the world, is threatened in its native range and classified as endangered by the International Union for Conservation of Nature. The global conservation strategy for the species includes ex situ conservation efforts led by zoological institutions in the framework of regional captive breeding programs. To maximize the conservation of genetic diversity and optimize breeding programs, an accurate pedigree must be established in captive populations. Our study documents the formation and subsequent monitoring of a large ring-tailed lemur group in a French zoological institution. Based on staff's behavioral observations and DNA analyses using 11 microsatellite markers, we were able to document the survival and reproduction rates of the lemurs in this situation and reconstruct the pedigree of infants born in the institution. In total, 22 of the 28 imported animals as well as 4 locally born individuals gave birth to 58 infants of which 28 survived. The consistent genotypes obtained from the 53 sampled animals allowed us to identify 25 of the sires and 27 of the dams for the 28 surviving infants. A total of 12 different females and 14 different males produced the 28 surviving infants, suggesting that no individual dominates reproduction. This pioneering study has practical applications for the captive management of the species, which can be raised to the individual level instead of the group level.

Should I stay or should I go? Individual movement decisions during group departures in red-fronted lemurs.

Collective movements are essential for maintaining group cohesion. However, group members can have different optimal departure times, depending on individual, social and contextual factors whose relative importance remains poorly known. We, therefore, studied collective departures in four groups of red-fronted lemurs (Eulemur rufifrons) in Kirindy Forest, Madagascar, to investigate the influence of an individual's age, sex, their affiliative relationships and their proximity to other group members at the time of departure on their individual departure decision. We recorded behavioural and spatial data on individual departures during 167 group movements and conducted group scans (181–279 per group) to assess affiliative relationships. All factors influenced individual departures. Both affiliation and proximity determined a mimetic joining process in which dyads with stronger affiliative bonds departed in closer succession, and individuals followed the initiator and predecessors more quickly when they were in closer proximity at departure. While the influence of affiliation is common, the effect of inter-individual distance has rarely been considered in groups with heterogeneous social relationships. Although local rules influenced joining, the overall movement pattern was mainly determined by individual traits: juveniles took protected central positions, while females made up the van and males brought up the rear. Individual needs, expressed in the departure order, to an extent overruled the effect of affiliation. These results highlight the importance of considering individual, social and contextual factors collectively in the study of collective movements.

Mutual grooming functions to prolong grooming received in ringtailed lemurs

Mutual (simultaneous) grooming occurs in a variety of mammals and is characterized by a distinct payoff structure compared to unidirectional grooming, as in mutual (but not in unidirectional) grooming both partners simultaneously get the benefits of the receipt of grooming. Mutual grooming, however, has been very little investigated. We studied a captive group of ringtailed lemurs, Lemur catta, to test the hypothesis that mutual grooming functions to prolong grooming received. Lemurs were more likely to initiate grooming when they were being groomed than when they were simply approached by a group mate. They were also less likely to terminate grooming if their partner was simultaneously grooming them. These results support the hypothesis that mutual grooming represents a form of immediate repayment of cooperation received that facilitates further investment by the partner. It remains to be ascertained how natural selection may favour mutual over unidirectional grooming in different social and ecological conditions.

Predictions of Seed Shadows Generated by Common Brown Lemurs (Eulemur fulvus) and Their Relationship to Seasonal Behavioral Strategies

Frugivorous primates in the family Lemuridae, the largest seed dispersers in Madagascar, often modify their behavior dramatically to cope with seasonal fluctuations in food availability and climate. Such behavioral strategies influence seed dispersal distances and seed shadows, which determine seed fate, gene flow, and the geographical range expansion of plant populations. To examine seasonal variation in seed shadows generated by the common brown lemur (Eulemur fulvus), I combined data on movements of a wild group of lemurs in northwestern Madagascar from full-day observations made twice weekly for 1 year and full-night observations made once a fortnight during the dry season, with gut passage times for three captive individuals in a Malagasy zoo. During the rainy season, brown lemurs increased traveling effort (mean daily path lengths: 1172 ± SE 59 m), adopting a high-cost/high-yield foraging strategy to maximize harvest under periods of fruit abundance; this resulted in long seed dispersal distances (median: 170 ± MAD 77 m). During the dry season, daily path lengths (mean: 469 ± SE 30 m) were shorter owing to midday resting and consumption of water-rich succulent leaves, probably to avoid overheating and dehydration. These behaviors led to short-distance seed dispersal (median: 75 ± MAD 47 m). Although brown lemurs moved nocturnally during the dry season (mean nightly path lengths: 304 ± SE 58 m), nocturnal seed dispersal distances were short (median: 34 ± MAD 21 m). This seasonal variation in seed shadows might cause different population dynamics for rainy- and dry-season-fruiting species of large-seeded plants that depend on brown lemurs for seed dispersal. Additionally, lemur-facilitated seed dispersal distances were shorter than those of large frugivores elsewhere in the world. Therefore, lemur-mediated seed dispersal systems are likely to be vulnerable to forest fragmentation, which can isolate new recruits and prevent gene flow among plant metapopulations.

The Search for the Intersection of Form and Function: Looking for Clues into What Has Determined How, Why, and When Animals Came to Move the Way They Do.

The Search for the Intersection of Form and Function: Looking for Clues into What Has Determined How, Why, and When Animals Came to Move the Way They Do.

Female infanticide and female-directed lethal targeted aggression in a group of ring-tailed lemurs (&amp;lt;i&amp;gt;Lemur catta&amp;lt;/i&amp;gt;)

Abstract. We report on extremely rare events of lethal aggression in a semi-captive group of ring-tailed lemurs (Lemur catta) during the birth season 2014. This aggression was targeted against the two highest-ranking females. It led to their eviction from the group and following a final aggressive interaction four days later to their deaths caused by almost all the females and probably even two males of their former group. These events of targeted aggression erupted initially following an infanticide by the highest-ranking female directed at the offspring of a subordinate. Even for ring-tailed lemurs this is a very special case of changeover of power between two different matrilines in a group. In accordance with other studies we suggest that these events of targeted aggression were based on the growing group size and were acts of female reproductive competition during birth season. With the intensity of the events we add new aspects to the existing knowledge of aggressive interactions in ring-tailed lemurs.

The influence of visitor interaction on the behavior of captive crowned lemurs (Eulemur coronatus) and implications for welfare

Research suggests that zoo visitors can have positive, negative, and neutral impacts on captive primate welfare; however, research investigating the implications of visitor-animal feeding experiences is extremely limited. In the UK, a large proportion of BIAZA zoos that house lemur species offer visitor interaction experiences (16 out of 33). This study investigated the impact on the behavior of a family group of crowned lemurs (Eulemur coronatus) housed at Newquay Zoo, UK of visitors, accompanied by a keeper, entering the enclosure to feed the lemurs. Behavior was observed under four conditions: (i) during visitor feed; (ii) 30 min post-visitor feed; (iii) during a keeper feed; and (iv) 30 min post-keeper feed. Keeper feeds were conducted by keepers only, on the day after visitor feeds. The lemur group spent significantly less time performing aggressive behavior and was also significantly more interactive with keepers during visitor feeds compared with keeper-only feeds. There was no significant difference in behaviors performed immediately after interacting with visitors. Over the study period, there was a tendency for interactions with visitors to increase, and for interactions with keepers during visitor feeds to decrease. After a 28-day interval without visitor interaction, the lemurs' interaction with visitors had returned to the level recorded at the start of the study. In conclusion, visitor interaction did not compromise the welfare of the study subjects in either the short- or long-term, while an increase in visitor interactions over time has interesting implications for the enrichment properties of, or habituation to, unfamiliar humans. Zoo Biol. 35:222-227, 2016. © 2016 Wiley Periodicals, Inc.

Lemurs groom-at-a-distance through vocal networks

Vocal exchanges are predicted to serve a social bonding function by allowing conspecifics to ‘groom-at-a-distance’. If vocalizations play a role in bonding, then they should be mainly exchanged between the socially bonded group members, and thus display high social selectivity that characterizes other affiliative behaviours such as grooming. However, whether or not vocal exchanges are driven by social bonds remains unclear. We investigated vocal selectivity by studying the relationships between contact-calling networks and grooming networks in multiple free-ranging groups of ringtailed lemurs, Lemur catta. Lemur grooming interactions were socially selective and were directed towards only some of their group members. However, their vocal exchanges displayed even higher levels of social selectivity. Instead of exchanging vocalizations with each group member they groomed, lemurs reserved their vocal responses mainly for the group members whom they had frequently groomed. We tested this vocal selectivity through a playback experiment in which we presented lemurs' calls to their group. Lemurs responded only to the playbacks of the conspecifics whose calls they had responded to while free-ranging, confirming that selective vocal responses do not depend on proximal (i.e. visual or olfactory) cues from the vocalizing lemur. These robust relationships between grooming and contact-calling networks in lemurs, a species that lives in small groups where grooming frequency reflects bond strength, demonstrates that vocal exchanges indicate the strong social bonds between conspecifics. Contact calls may serve a bonding function in social species by allowing the strongly bonded group members to groom-at-a-distance when they are separated from each other.

Beyond the Gallery Forest: Contrasting Habitat and Diet in Lemur catta Troops at Bezà Mahafaly Special Reserve

Ring-tailed lemurs have been studied intensively in the Parcel 1 gallery forest of Bezà Mahafaly Special Reserve. Here, we report on lemur groups in a mixture of deciduous dry forest and spiny forest just 5 km to the west. Compared to Parcel 1, Parcel 2 (P2) has a lower density of Tamarindus indica, a major dietary plant species for gallery forest lemurs. Recent studies in drier habitats have called into question the association of lemur density and tamarind presence. In order to address this question, we measured forest structure and composition of plant plots between parcels and conducted lemur feeding observations. The trees and shrubs within the parcels did not differ in height or diameter at breast height, but the frequencies of plant species that were common between parcels were significantly different. Numbers of feeding observations on foods common to both parcels did not differ, but their relative rankings within parcels did. Frequencies of food plants corresponded to earlier reports of lemur population densities. However, we found that the ring-tailed lemur diet is a mixture of plants that are eaten in abundance regardless of frequency and those that are locally available. In terms of their reliance on Tamarindus, P2 animals appear intermediate between those in gallery forests and nontamarind sites.

Innovation and behavioral flexibility in wild redfronted lemurs (Eulemur rufifrons).

Innovations and problem-solving abilities can provide animals with important ecological advantages as they allow individuals to deal with novel social and ecological challenges. Innovation is a solution to a novel problem or a novel solution to an old problem, with the latter being especially difficult. Finding a new solution to an old problem requires individuals to inhibit previously applied solutions to invent new strategies and to behave flexibly. We examined the role of experience on cognitive flexibility to innovate and to find new problem-solving solutions with an artificial feeding task in wild redfronted lemurs (Eulemur rufifrons). Four groups of lemurs were tested with feeding boxes, each offering three different techniques to extract food, with only one technique being available at a time. After the subjects learned a technique, this solution was no longer successful and subjects had to invent a new technique. For the first transition between task 1 and 2, subjects had to rely on their experience of the previous technique to solve task 2. For the second transition, subjects had to inhibit the previously learned technique to learn the new task 3. Tasks 1 and 2 were solved by most subjects, whereas task 3 was solved by only a few subjects. In this task, besides behavioral flexibility, especially persistence, i.e., constant trying, was important for individual success during innovation. Thus, wild strepsirrhine primates are able to innovate flexibly, suggesting a general ecological relevance of behavioral flexibility and persistence during innovation and problem solving across all primates.Electronic supplementary materialThe online version of this article (doi:10.1007/s10071-015-0844-6) contains supplementary material, which is available to authorized users.

The socio-matrix reloaded: from hierarchy to dominance profile in wild lemurs.

Dominance hierarchy influences the life quality of social animals, and its definition should in principle be based on the outcome of agonistic interactions. However, defining and comparing the dominance profile of social groups is difficult due to the different dominance measures used and because no one measure explains it all. We applied different analytical methods to winner-loser sociomatrices to determine the dominance profile of five groups of wild lemurs (species: Lemur catta, Propithecus verreauxi, and Eulemur rufus x collaris) from the Berenty forest (Madagascar). They are an excellent study model because they share the same habitat and an apparently similar dominance profile: linear hierarchy and female dominance. Data were collected over more than 1200 h of observation. Our approach included four steps: (1) by applying the binary dyadic dominance relationship method (I&SI) on either aggressions or supplant sociomatrices we verified whether hierarchy was aggression or submission based; (2) by calculating normalized David’s scores and measuring steepness from aggression sociomatrices we evaluated whether hierarchy was shallow or steep; (3) by comparing the ranking orders obtained with methods 1 and 2 we assessed whether hierarchy was consistent or not; and (4) by assessing triangle transitivity and comparing it with the linearity index and the level of group cohesion we determined if hierarchy was more or less cohesive. Our results show that L. catta groups have got a steep, consistent, highly transitive and cohesive hierarchy. P. verreauxi groups are characterized by a moderately steep and consistent hierarchy, with variable levels of triangle transitivity and cohesion. E. rufus x collaris group possesses a shallow and inconsistent hierarchy, with lower (but not lowest) levels of transitivity and cohesion. A multiple analytical approach on winner-loser sociomatrices other than leading to an in-depth description of the dominance profile, allows intergroup and cross-species comparisons.