Interannual Variation in Diet, Dietary Diversity, and Dietary Overlap in Three Sympatric Strepsirrhine Species in Southeastern Madagascar

Interrelationship among spatial cohesion, aggression rate, counter-aggression and female dominance in three lemur species

Abstract

How social and ecological factors are associated with variation in dominance style across species of animals has been studied frequently, but the underlying processes are often not addressed. Theoretical research indicates that stronger spatial cohesion among individuals in a group causes a higher frequency of fighting and, thus, through the self-reinforcing effects of winning and losing fights, a stronger differentiation of the dominance hierarchy and dominance of females over more males. Our aim in the present paper is to study whether the same interrelationship among processes may underlie differences in dominance style among three species of lemur that differ in their degree of despotism: Lemur catta, Propithecus verreauxi and Eulemur rufifrons. We investigated their agonistic interactions and spatial cohesion based on 2752 h of observational data of 20 wild groups of these three species. We determined dominance style using the proportion of counter-aggression, with a lower proportion indicating a more despotic dominance style. We found that stronger spatial cohesion among individuals is associated with a higher rate of aggression, stronger despotism and dominance of females over more males. The results of our study emphasise the general importance of spatial cohesion in determining dominance style.

Significance statement

Theoretical studies have shown that the spatial configuration of individuals in a group influences the dominance style. In an agent-based model, DomWorld, individuals are guided by simple rules of grouping and fighting and emergent patterns of behaviour switch between resembling those of despotic or egalitarian primates depending on the degree of cohesion in groups. Yet this link has seldom been studied empirically. We, therefore, examine the relevance of spatial cohesion on patterns of behaviour of individuals in groups of three species of lemur. We confirm the predictions from the model and show that stronger spatial cohesion results in more frequent aggression, a more despotic dominance style and stronger female dominance over males. In light of this, we urge future research of animal dominance to include measures of cohesion.

Environmental and anthropogenic influences on movement and foraging in a critically endangered lemur species, Propithecus tattersalli: implications for habitat conservation planning

BACKGROUND

Wildlife conservation often focuses on establishing protected areas. However, these conservation zones are frequently established without adequate knowledge of the movement patterns of the species they are designed to protect. Understanding movement and foraging patterns of species in dynamic and diverse habitats can allow managers to develop more effective conservation plans. Threatened lemurs in Madagascar are an example where management plans and protected areas are typically created to encompass large, extant forests rather than consider the overall resource needs of the target species.

METHODS

To gain an understanding of golden-crowned sifaka (Propithecus tattersalli) movement patterns, including space use and habitat selection across their range of inhabited forest types, we combined behavior data with Dynamic Brownian Bridge Movement Models and Resource Selection Functions. We also examined the influence of abiotic, biotic, and anthropogenic factors on home range size, movement rates, and foraging patterns.

RESULTS

We found that home range size and movement rates differed between seasons, with increased core area size and movement in the rainy season. Forest type also played a role in foraging behavior with sifaka groups in the humid forest avoiding roads in both seasons, groups in the dry deciduous forest avoiding road networks in the rainy season, and groups in the moderate evergreen forest displaying no selection or avoidance of road networks while foraging.

CONCLUSION

Our study illustrates the importance of studying primate groups across seasons and forest types, as developing conservation plans from a single snapshot can give an inaccurate assessment of their natural behavior and resources needs of the species. More specifically, by understanding how forest type influences golden-crowned sifaka movement and foraging behavior, conservation management plans can be made to the individual forest types inhabited (dry deciduous, moderate evergreen, humid, littoral, etc.), rather than the region as a whole.

Habitat use by the island lemurs of Nosy Be, Madagascar

Madagascar's lemurs are threatened by forest loss, fragmentation, and degradation. Many species use flexible behaviors to survive in degraded habitat, but their ability to persist in very small areas may be limited. Insular lemurs, like those found on Nosy Be, an island off the northwestern coast of Madagascar, are at heightened risk of sudden population declines and extirpation. Nosy Be is home to two Critically Endangered species-the endemic Nosy Be sportive lemur (Lepilemur tymerlachsoni) and Claire's mouse lemur (Microcebus mamiratra)-as well as the Endangered black lemur (Eulemur macaco). Most of the remaining forest on Nosy Be is protected by the 862-ha Lokobe National Park. To document how Nosy Be lemurs use their restricted habitat, we conducted vegetation and reconnaissance surveys on 53 transects in and around Lokobe. We collected data on tree size, canopy cover, understory visibility, and elevation for 248 lemur sightings. We used a spatially explicit, multi-species occupancy model to investigate which forest-structure variables are important to lemurs. Our results represent some of the first data on habitat use by insular lemurs. Black lemurs preferred significantly larger trees and areas with less dense understory. They also occurred significantly less outside of Lokobe National Park, even when accounting for sampling effort and geography. The distributions of the sportive and mouse lemurs were not related to the forest structure variables we documented, but they did negatively predict each other-perhaps because their habitat requirements differ. These results also underscore the importance of the national park to protecting the black lemur population on Nosy Be and raise questions about what factors do influence the distribution of Nosy Be's smaller lemurs. Close monitoring is needed to prevent these populations and the ecosystem services they provide from disappearing, as have other island lemurs.

Black-and-White Ruffed Lemur (Varecia variegata) in Captivity: Analysis of the Oral Microbiota in a One Health Perspective

This study aimed to characterize the susceptibility profile to antibiotics and biofilm formation of Gram-negative bacterial isolates obtained from the oral cavity of the black-and-white ruffed lemur (Varecia variegata). From eight individuals from a zoo located in Portugal, samples of the oral microbiota were collected with sterile swabs and then placed in closed tubes with a transport medium. Culture was carried out for media of Gram-negative bacteria. Twenty-two isolates were obtained and subjected to susceptibility tests to twenty-five antimicrobial agents belonging to seven different classes. All tested isolates demonstrated resistance to, at least, one antibiotic, and it was possible to observe multidrug resistance in 11 of the 22 isolates (50%). It should be noted that an isolate showed phenotypic resistance to imipenem, an antibiotic for exclusive use in a hospital environment. All the isolates showed an increasing ability of biofilm formation over time. The obtained results show that wild mammals in captivity could be reservoirs and potential sources of multi-resistant pathogens. In view of this fact and considering the One Health concept, it will be advisable to establish local monitoring programs worldwide that benefit and protect human, animal and environmental health.

Realized distribution patterns of crowned lemurs (Eulemur coronatus) within a human-dominated forest fragment in northern Madagascar

Due to the impact of anthropogenic activities on forest extent and integrity across Madagascar, it is increasingly necessary to assess how endangered lemur populations inhabiting human-dominated forest fragments can effectively sustain themselves ecologically. Our research addresses this concern by exploring how the distribution patterns of a small population of crowned lemurs (Eulemur coronatus), occupying a degraded forest fragment at Oronjia Forest New Protected Area in northern Madagascar, are impacted by the availability of key ecological and anthropogenic factors. We hypothesize that the distribution of E. coronatus within the fragment is limited by the availability of critical ecological resources and conditions and the intensity of anthropogenic features and activities. To examine this, we used MaxEnt to develop a species distribution model using presence-only occurrence records and 10 independent background covariates detailing the site's ecological and anthropogenic aspects. The results indicate that the realized distribution patterns of E. coronatus within human-dominated forest fragments are strongly associated with sections of forest that contain sparsely and sporadically distributed resources, such as freshwater and continuous hardwood vegetation. We conclude that the distribution of E. coronatus at Oronjia is shaped by their need to maximize foraging opportunities in a degraded forest landscape where they are subject to both environmental and anthropogenic stressors.

Comparative ecological and behavioral study of Macaca assamensis and M. mulatta in Shivapuri Nagarjun National Park, Nepal

Resource partitioning reduces the competition between different species within the same habitat, promoting their coexistence. To understand how such species co-adapt to reduce conflicts, we examined the behavior of two primates, Assamese macaque (Macaca assamensis) and rhesus macaque (Macaca mulatta), from April 2017 to March 2018 in Sivapuri Nagarjun National Park (SNNP), Kathmandu Valley, Nepal. We performed 1580 and 1261 scan sessions on wild multi-male/multi-female groups of Assamese and rhesus macaques, respectively, at 15-min sampling intervals. Assamese macaques consumed fewer plant species (38 species) than rhesus macaques (88 species). Overlapping food sources between the macaque species resulted in a Pianka index of 0.5. Assamese macaques consumed more items of tree, climber, and vine species, whereas rhesus macaques fed on more shrub, herb, and grass species. The proportions of plant parts consumed by the two species differed-more leaves, fruits and cones were used by Assamese macaques than rhesus macaques, whereas more flowers, seeds, and pods were consumed by rhesus macaques than Assamese macaques. Assamese macaques had a smaller home range (0.55 km²) than rhesus macaques (4.23 km²), and Assamese macaques had a shorter daily moving distance (1.6 km) than rhesus macaques (4.0 km). Although feeding time did not differ between the two macaque species, less time was devoted to social activities by Assamese macaques (16.0%) than by rhesus macaques (33.7%). Assamese macaques were generally arboreal, with 94.0% of their activities in trees, whereas rhesus macaques were largely terrestrial, with 58.5% of their activities on the ground. These differences in food selection, home-range size, ranging and activity patterns, and habitat use suggest that Assamese and rhesus macaques reduce resource competition through resource partitioning to coexist in a landscape matrix.

Ecometric modelling of tooth shape and precipitation gradients among lemurs on Madagascar

Ecometric modelling relates spatial environmental variables to phenotypic characters to better understand morphological adaptation and help reconstruct past environments. Here, the community means of the dental topography metrics Dirichlet normal energy (DNE) and orientation patch count (OPC) are tested against annual precipitation and precipitation seasonality among lemurs across Madagascar. Dry, seasonal environments are expected to be associated with high DNE and OPC, as lemurs living in these environments are more likely to rely on tougher foods. Ecometric models are also used to calculate ecometric loads for lemur taxa hypothesized to be experiencing evolutionary disequilibria and to reconstruct annual precipitation and precipitation seasonality at the ~500 years BP subfossil cave site of Ankilitelo. DNE was highest in highly seasonal but wet environments. Seasonal exploitation of fallback foods and the availability of new leaves during wet periods may be most important in driving community DNE. OPC was weakly predicted by annual precipitation and seasonality but its distribution appeared to be driven by a stepwise increase in its community values in rainforest environments. The lemur fauna from Ankilitelo appears to resemble communities from moister environments than occur in the spiny desert zone in which the site is situated today.

A description of nesting behaviors, including factors impacting nest site selection, in black-and-white ruffed lemurs (Varecia variegata)

Nest site selection is at once fundamental to reproduction and a poorly understood component of many organisms' reproductive investment. This study investigates the nesting behaviors of black-and-white ruffed lemurs, Varecia variegata, a litter-bearing primate from the southeastern rainforests of Madagascar. Using a combination of behavioral, geospatial, and demographic data, I test the hypotheses that environmental and social cues influence nest site selection and that these decisions ultimately impact maternal reproductive success. Gestating females built multiple large nests throughout their territories. Of these, females used only a fraction of the originally constructed nests, as well as several parking locations as infants aged. Nest construction was best predicted by environmental cues, including the size of the nesting tree and density of feeding trees within a 75 m radius of the nest, whereas nest use depended largely on the size and average distance to feeding trees within that same area. Microhabitat characteristics were unrelated to whether females built or used nests. Although unrelated to nest site selection, social cues, specifically the average distance to conspecifics' nest and park sites, were related to maternal reproductive success; mothers whose litters were parked in closer proximity to others' nests experienced higher infant survival than those whose nests were more isolated. This is likely because nesting proximity facilitated communal crèche use by neighboring females. Together, these results suggest a complex pattern of nesting behaviors that involves females strategically building nests in areas with high potential resource abundance, using nests in areas according to their realized productivity, and communally rearing infants within a network of nests distributed throughout the larger communal territory.